Spring 2021
Troutdale
  Troutdale 
Observation 
Deck
Evan Kristof
PSU Civil & Environmental Engineering Capstone

Spring 2021 Troutdale
Troutdale Observation Deck
Evan Kristof
Senior Instructor • Department of Civil and Environmental Engineering
PORTLAND STATE UNIVERSITY
Acknowledgments
The team would like to thank our primary clients Chris Damgen and 
Amber Shackelford at the City of Troutdale for providing our senior 
capstone class the opportunity to put our engineering education 
into practice. We would like to thank our instructor and office 
manager Evan Kristof for facilitating the project and for his help 
with the structural design. We would also like to thank Dr. Arash 
Khosravifar for his help with the foundation and pile design.
This report was prepared as part of a class project for the Civil 
and Environmental Engineering Project Management and Design 
course at Portland State University. The contents of this report were 
developed by the student authors and do not necessarily reflect the 
views of Portland State University. The analyses, conclusions, and 
recommendations contained in the report should not be construed 
as an engineering report or used as a substitute for professional 
engineering services.
This report represents original student work and recommendations 
prepared by students in the Sustainable City Year Program for the 
City of Troutdale. Text and images contained in this report may not 
be used without permission from the University of Oregon.
Contents
4 About SCI
4 About SCYP
5 About City of Troutdale
6 Course Participants
7 Executive Summary
9 Introduction
9 1.0 Project Background
16 2.0 Alternatives Analysis
29 3.0 Facility Design
40 4.0 Regulatory Compliance and Permitting
41 5.0 Conclusion
42  References
43 Appendices
Spring 2021 Troutdale Observation Deck
About SCI
The Sustainable Cities Institute (SCI) 2. Our Urbanism Next Center, which 
is an applied think tank focusing on focuses on how autonomous vehicles, 
sustainability and cities through applied e-commerce, and the sharing economy 
research, teaching, and community will impact the form and function of 
partnerships. We work across cities. 
disciplines that match the complexity 
of cities to address sustainability In all cases, we share our expertise 
challenges, from regional planning to and experiences with scholars, 
building design and from enhancing policymakers, community leaders, and 
engagement of diverse communities project partners. We further extend 
to understanding the impacts on our impact via an annual Expert-in-
municipal budgets from disruptive Residence Program, SCI China visiting 
technologies and many issues in scholars program, study abroad course 
between. on redesigning cities for people on 
SCI focuses on sustainability-based bicycle, and through our co-leadership 
research and teaching opportunities of the Educational Partnerships for 
through two primary efforts: Innovation in Communities Network 
(EPIC-N), which is transferring SCYP 
1. Our Sustainable City Year Program to universities and communities 
(SCYP), a massively scaled university- across the globe. Our work connects 
community partnership program that student passion, faculty experience, 
matches the resources of the University and community needs to produce 
with one Oregon community each innovative, tangible solutions for the 
year to help advance that community’s creation of a sustainable society.
sustainability goals; and
About SCYP
The Sustainable City Year Program learning courses to provide students 
(SCYP) is a year-long partnership with real-world projects to investigate. 
between SCI and a partner in Oregon, Students bring energy, enthusiasm, 
in which students and faculty in courses and innovative approaches to difficult, 
from across the university collaborate persistent problems. SCYP’s primary 
with a public entity on sustainability value derives from collaborations 
and livability projects. SCYP faculty that result in on-the-ground impact 
and students work in collaboration with and expanded conversations for a 
staff from the partner agency through community ready to transition to a 
a variety of studio projects and service- more sustainable and livable future.
4
About City of Troutdale
About City of Troutdale
Troutdale is a dynamic suburban community in Multnomah 
County, situated on the eastern edge of the Portland 
metropolitan region and the western edge of the Columbia 
River Gorge. Settled in the late 1800s and incorporated in 
1907, this “Gateway to the Gorge” is approximately six square 
miles in size with a population of nearly 17,000 residents. 
Almost 75% of that population is aged 18-64.
Troutdale’s median household beautiful natural setting, miles of trails, 
income of $72,188 exceeds the State and parkland and conservation areas 
of Oregon’s $59,393. Troutdale’s draw residents and visitors alike. The 
neighbors include Wood Village and City’s pride in place is manifested 
Fairview to the west, Gresham to the through its monthly gatherings and 
south, and unincorporated areas of annual events, ranging from “First 
Multnomah County to the east. Friday” art walks to the city’s long-
For the first part of the 20th century, standing Summerfest celebration 
the city remained a small village serving each July. A dedicated art scene and 
area farmers and company workers an exciting culinary mix have made 
at nearby industrial facilities. Starting Troutdale an enviable destination and 
around 1970, Troutdale became a underscore the community’s quality of 
bedroom community in the region, with life. Troutdale is home to McMenamins 
subdivisions and spurts of multi-family Edgefield, one of Portland’s beloved 
residential housing occurring. In the venues for entertainment and 
1990s, efforts were made to improve hospitality.
the aesthetics of the community’s In recent years, Troutdale has 
original core, contributing to an award- developed a robust economic 
winning “Main Street” infill project that development program. The City’s 
helped with placemaking. In the 2010s, largest employers are Amazon and 
the City positioned itself as a jobs FedEx Ground, although the City 
center as it worked with stakeholders to also has numerous local and regional 
transform a large superfund area to one businesses that highlight unique assets 
of the region’s most attractive industrial within the area. Troutdale’s recent 
centers – the Troutdale-Reynolds business-related efforts have focused 
Industrial Park. on the City’s Town Center, where 12 
The principal transportation link “opportunity sites” have been identified 
between Troutdale and Portland is for infill development that respects the 
Interstate 84. The Union Pacific Railroad small-town feel while offering support 
main line runs just north of Troutdale’s to the existing retail environment. The 
city center. The Troutdale area is the next 20 years promise to be an exciting 
gateway to the famous Columbia River time for a mature community to protect 
Gorge Scenic Area and Sandy River what’s loved and expand opportunities 
recreational areas, and its outdoor that contribute to Troutdale’s pride in 
pursuits. Troutdale’s appealing and place.
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Spring 2021 Troutdale Observation Deck
Course Participants
CASEY KELLER
ANDREW HILL
ANH LE
JILLIAN PFEIFER
JUSTIN POTTS
JORDAN REAL
ELIJAH KING
MATTHEW STEWART
ELIZABETH GARTNER
LEEN QWIDER
BROOKE ANNOTTI
ARTHUR YUROV
EZRA ALBRIGHT
IAN BUSLACH
SAVKO ZAGARYUK
MARIE ROZA
TRAN TRAN
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Troutdale O bservaon D eck  (2021.TROUT.03) 2021  
D esign R eport ( Dra�  II)  
EX ECUTIVE S  UMMARY  
The C ity  of  Troutdale  has  planned  to  construct  Sandy  Riverfront  Park  on a   reclaimed s ite  just  
north  of d owntown  Troutdale, w hich  previously h oused a n  old w ater t reatment  plant. T he p ark  
will b e p art o f T routdale’s U rban R enewal P roject, w hich  aims t o  create a   natural s pace f or  
walkers a nd  bicyclists t o e njoy t he  local  flora  and t he S andy  River. T he c ity  requested  a  
cantilevered  deck d esigned a t 3 0% t o  provide a   commanding  view o f  the  river  and  serve  as a  r est  
area  for p ark  visitors.  The  design c onsiderations i nclude c ost-effectiveness,  minimal  deck  
deflection,  minimal  obstruction  to  existing s ite  conditions,  and e ase o f  access f or l ong-term  
maintenance t asks.  
  
The  proposed c antilever d eck d esign w as  based  on a   “short a nd w ide”  layout,  with  a l onger w idth  
parallel  to t he  trail  and  a c omparatively s horter  cantilever l ength.  After  several  design  iterations  
and f eedback f rom  the C ity o f  Troutdale, t he p roposed  design w as  restructured  into a  r oughly  
square  deck,  with a   width o f 1 8’  and  a  cantilever  length o f  17’. T he  reasoning b ehind t his  ultimate  
design  includes e nhancing t he  view  of t he  Sandy  River  and p roviding e nough  space  for  both  
visitors  and  amenities, s uch a s  benches.  
  
Materials  involved  in  the  design w ere  chosen b ased o n c lient  preference, e ase  of m aintenance, a nd  
overall r esiliency.  The d ecking m aterial  chosen w as  pultruded f iberglass p aneling, t he  same  
material t hat  will  be u sed i n t he  elevated w alkway f rom  the  Sandy  Riverfront P ark T rail p lan.  
These p anels  are  a  plastic  product r einforced w ith f iberglass  and a re a ppropriately r eferred t o  as  
“fiberglass r einforced p lastic”  (abbreviated a s  FRP).  The  material  is l ightweight, w eather-resistant,  
and  manufactured  to  be A DA-compliant  and  slip-resistant. F RP  can a lso b e m anufactured i n g rate  
panels,  allowing e asy  maintenance  and s uperb d rainage.  
  
Six s teel s tringers s upport t he  decking; a ll s ix u tilize t he  wide f lange b eam  shape  due  to  its  
universal a pplication i n m ost  designs  and  high f lexural s trength-to-weight  ratio. T hese s tringers  
will b e  spaced 3 .4’  on-center  to k eep  the d eflections o f  the  deck p anels w ithin  the a llowable  
tolerance, w hile m inimizing  the  number o f s tringers u tilized.  
  
There  will  be  two  reinforced c oncrete g irders  below t he s teel s tringers;  these g irders w ill  span t he  
17’  cantilever d istance  and  an  additional  1.5  times t he c antilever  distance ( 25.5’),  with  a t otal  
girder l ength o f 4 2.5’.  The  additional l ength e xtends  behind t he  cantilever a s t he  “backspan”, a nd  
acts  as  a  balance a gainst  the b ending f orce  exerted o n  the  cantilevered p ortion.  This b ackspan w ill  
be  buried b elow g rade f rom  beyond w here t he d eck  ends,  and  the  weight o f t he t opsoil w ill  
provide a dditional  resistance a gainst b ending. S ince  the g irders w ill b e  in c ontact  with  soil  
throughout  their  service l ife,  they w ill  be  constructed  of r einforced  concrete. T his  material w as  
chosen f or i ts e xtensive  corrosion  resistance w hen  compared  to s teel,  as w ell  as  its  great  
compressive  strength.  
  
Since t he  site  is  sloped, a   standalone r etaining w all  is r ecommended  to p revent s oil  erosion f rom 
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T routdale O bservation  Deck  (2021.TROUT.03) 2021  
F inal  Design  Report  
  
the  loading  on  the  deck. T he r etaining w all  will b e l ocated a t  the  beginning  of t he c antilever. T he  
structure  will b e  founded u pon  spread  footings o f r einforced  concrete a nd c onnected t o t he  
backspan p ortion o f t he g irders.  This s tyle o f  foundation  was s elected  for  its  simplicity  in  
construction. T here  was  also a  l ack  of d eep s oil d ata a t  the s ite -   if  more d ata  was  available, i t  
could g uide d eep p ile  foundation d esign  instead o f  spread f ooting d esign.  
  
Included i n t his  report  is  the 3 0%  design p lan  set a nd a  c onstruction  cost  estimate.  This  
preliminary d esign  report  informs  the  City  of  Troutdale t he  magnitudes o f  cost  and c onstruction  
efforts n eeded  to b ring t he p roject t o c ompletion. A s  such,  the d esign m ay b e  modified a ccording  
to t he p references a nd  vision o f  the C ity.  
  
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IN TRODUCTION  
The  City  of  Troutdale h as a  p lanned  park a nd  trail s ystem r unning a long  the S andy  River. T he C ity  
wished t o  provide  trail  users  with  a  scenic r est  area a nd a   commanding  view o f  the  river,  and  
expressed a   preference f or  a  cantilevered o bservation d eck  to  accomplish t his. T he 2 021  Portland  
State  University  Capstone g roup, 2 021.TROUT.03, h as  been  assigned t o  compile  a  30% d esign  
package  and c ost e stimate. T he p ackage  will  include s heets  containing p lan a nd  profile  views  of  
the  structure  on-site,  super-  and s ubstructure d imensions, a nd  detail  sheets.   
  
1.0 P R OJECT B A CKGROUND  
The  scope o f t he  project i s t o d esign  an o bservation d eck f or  the S andy R iverfront P ark f or  the  city  
of  Troutdale. T he S andy  Riverfront P ark i s  a f uture  project  that  is  part  of  the  city's 2 0-year  plan  
for t he  Urban  Renewal A rea  (URA) p rogram,  consisting o f  a  3 m illion d ollar  clean-up  of  the  
Sandy R iverfront. T he f uture  park  will  occupy 2 0 a cres  of l and a long t he S andy R iver,  just  north  
of  Depot C ity  Park a nd d owntown T routdale. T he  new  park w ill b e a   natural  attraction  for  
residents a nd t ourists  to e njoy  while o ut w alking t he  trails  or s hopping  in  Troutdale’s d owntown  
area.  The p roposed o bservation  deck w ill e nhance  the p ark w ith a n  impressive  view  of  the  Sandy  
River  and w ill t ie  in w ith t he p lanned  Sandy  River A ccess  Trail.  
  
The s ite  of t he  Sandy  Riverfront P ark  has h ad t he h istoric w ater t reatment  structures r emoved. T he  
Sandy R iver A ccess  Trail  project h as c ompleted i ts  60%  design p hase,  which  includes  a s ection o f  
trail t hat  will  feature  an o ffshoot p ath l eading u p t o t he  observation d eck. A n  arborist  report  
evaluating n ative  and  invasive t ree s pecies h as b een c onducted,  and  provides g uidance o n  which  
thickets  to  avoid  constructing  by. A  g eotechnical  evaluation  of t he s ite s oil p roperties w as  also  
completed  and c ompiled i n a  r eport  by  GRI.  
  
The  ultimate g oal  of  the p roject  is t o d eliver a   30%  cantilevered  deck d esign  package t o t he C ity  
of  Troutdale. D esign c alculation s heets,  drafted p lan  sets, a nd c onstruction  cost  estimates w ill  
fulfill t his  deliverable. C ollaboration w ith a nd  guidance  from t he l andscape  architect  and  
engineers d esigning  the  Sandy R iverfront P ark  trails i s c ritical t o  facilitate p roject  development.  
Feedback  from t hese d esign  professionals  will  also e nsure  that  the d eck’s  design e lements  are  
congruent  with  their t rail d esigns.  
   
1.1 E X ISTING S  ITE C O NDITIONS  
The s pecific s ite l ocation i s t he  future  Sandy  Riverfront  Park. I t  is  located  on t he e mbankment  
of  the S andy R iver  at  the c onfluence  site  in  Troutdale  Urban  Renewal A rea, a nd  is o utlined i n  
red  in  Figure 1 .1. T he p ark  terrain i ncludes  gravel t rails,  sections o f  grass, t hickets  of  brush  
and  blackberry  bushes, a nd a  c ollection o f t rees  along  the r iverbank.  See  Figure  2.10 f or  a  
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Troutdale O bservation D eck ( 2021.TROUT.03) 2021  
Final D esign  Report  
  
magnified a erial  view o f t he c urrent  site. T here i s a   stormwater  outfall p ipe  extending o ut  from  
the r iver  bank  towards  the  river  (Figure  1.3), w ith a  2 0’-wide e asement.  
  
The  layout  of  the  site  and  its  use  has  changed  multiple t imes  over  the p ast  100 y ears. U SGS  
historical m aps  show t he h istoric  changes t o t his s ite f rom  1918  to 2 020.  One  important p iece  
of i nformation  that c an b e  discerned f rom t he o ldest  geological h istoric  map  from 1 918  is  that  
the  location o f t he  western  river  bank  has  not  moved d rastically i n t he  last  100 y ears  (Figure 
1.10).  This p articular c ondition i s a   solid  ground f or  designing  in  this  area s ince t he m ovement  
of t he  contours  is m inimal.   
  
The  historic  site  uses a nd  features  can b e  seen  on t he U SGS m aps  in F igures 1 .4-1.9. T he  
current  site  layout i s  displayed  in  Figure  1.4.  In 1 918,  a r oad r an p arallel t o t he  Sandy  River  
through  a  portion o f t he  site  (Figure  1.5).  A h istoric c reek a lso r an t hrough t he  middle o f  the  
site  into  the  river. I n  1941, a  C amas,  WA  map, s hows t he  formation  of a  s mall i sland  in t he  
middle  of t he r iver n ear t he s ite  (Figure  1.6);  the i sland  was s maller t han t he  current  island  
seen t oday.  A  Camas,  WA m ap  from 1 954 d isplays  the  I-84 h ighway c rossing t he r iver  on t he  
upper  edge  of t he s ite  (Figure 1 .7). T he  historic  creek  seen  in  the  1918  map i s f illed, a nd  
additional  infrastructure  has  been a dded ( including a  w ater t ank). I n 1 975,  the C amas, W A  
map d isplayed a  b lack  and  white  aerial  image  taken  over T routdale  and  the  site  (Figure 1 .8).  
Finally, t he 1 993 C amas,  WA m ap  shows t he l ocation  of t he  previous  wastewater  treatment  
plant t hat  took u p a  p ortion o f  the s ite  (Figure 1 .9).  As p art  of  the  Urban  Renewal A rea, a nd i n  
preparation  for t he  new  Sandy  Riverfront  Park,  the  wastewater  treatment  structures  on  site 
have  been r emoved.   
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Figure 1 .1:  Area  Map  with P roposed P roject L ocation  (highlighted  in  red)  
  
  
  
Figure 1 .2: C urrent S ite C onditions  looking E ast f rom  Site E ntrance  along  Interstate-84  
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Figure 1 .3:  Drone  Photo o f  Current  Site C onditions f rom  Above  Sandy R iver L ooking N orthwest  
  
  
Figure 1 .4: C urrent m ap Figure  1.5: 1 918 m ap   
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Troutdale O bservation D eck ( 2021.TROUT.03) 2021  
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Figure  1.6: 1 941 m ap Figure 1 .7: 1 954  map  
  
Figure  1.8:  1975 m ap Figure 1 .9: 1 993 m ap  
  
  
Figure 1 .10: O verlay  of 1 918  map  over a  c urrent m ap s howing  river  bank  
  
  
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Final  Design  Report  
  
1.2  ST AKEHOLDERS  
This p roject w as  initiated  by t he  City o f  Troutdale a s p art  of  the S andy  River A ccess P lan. T he  
city o f T routdale c ollaborated  with  Oregon  Metro, E astwinds D evelopment, L LC,  Sandy  River  
Watershed C ouncil,  and T routdale  Parks  and F acilities.  End-users o f t he O bservation D eck  
shall  be  the l ocal  public.   
  
1.2.1 T he  City o f  Troutdale ( Urban R enewal  Agency)  
The  City o f  Troutdale’s U rban R enewal  Agency i s  the p rincipal  stakeholder. T hey a re  the  
originators o f t he  Sandy R iver  Access  Plan, w hich  the  observation  deck i s p art  of. T hey  
have  the  final s ay  over  planning  and  design  decisions a nd  serve a s  a  link b etween t he  
various  stakeholders,  contractors,  and  human r esources b eing  utilized  for  the p roject.  
Chris D amgen  is  the  primary c ontact a t  the C ity  of  Troutdale  who i s  overseeing  the  
project.  
  
1. 2.2 O regon M etro  
The C ity  of  Troutdale h as  submitted  an a pplication f or a  N IN ( Nature i n N eighborhoods)  
grant  from  Oregon M etro  for  this p roject.  Oregon M etro  collects  revenue  from p roperty  
taxes a nd e nterprise a ctivities. T hese  funds  are  then  disbursed  as g rants  to v oter-approved  
programs s uch  as  Nature i n N eighborhoods,  which  focuses o n  the r estoration  of  and  
sustainable  access t o n ature  sites i n  Oregon’s p opulated  areas.  Oregon  Metro’s  input  will  
be  considered  in d etermining  the a ppropriate  allocation o f f unds t hroughout  the  life  of t he  
project.  
  
1.2.3 E A STWINDS D E VELOPMENT,  L LC  
Eastwinds D evelopment, L LC  is a   private c ompany t hat o wns 3 5%  (7  acres) o f  the  
property  being  developed i n  the  Sandy  River A ccess  Plan.  Eastwinds  has  enthusiastically  
partnered w ith  the C ity  of T routdale  on t his  project  and  intends t o m atch  the  funds  
provided b y  the  Nature i n N eighborhoods g rant  from  Oregon M etro.  They  have  
committed t o p roviding o n-site  project m anagement, p rinting,  and  supplies. A s a   major  
sponsor,  Eastwinds  should  have a   considerable s ay  in  determining t he  appropriate  
allocation  of  funds t hroughout  the  project.  As  a  landowner,  Eastwinds  should a lso b e  
considered a  r esource  for  site-specific/access-related  inquiries  throughout  planning  and  
construction.  
  
1.2.4 S A NDY R I VER  BA SIN  WA TERSHED C O UNCIL  
The  Sandy  River  Basin W atershed C ouncil i s a   non-profit  involved  in r estoring  and  
conserving r esources a nd h abitats o f  the S andy  River,  as  well a s i ts t ributaries.  The  
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Council  is  committed t o r ecruiting a dditional s takeholders  through t heir e xisting p artners  
who  can p rovide t echnical s upport  in  defining h ow  this p roject  can  interface w ith  existing  
restoration e fforts  in t he a rea. T he  Council  and  its  partners w ill  be  useful  when  
considering s tormwater  and  FEMA f lood  line i mpacts o n  the s tructure.  
  
1.2.5 T R OUTDALE  PA RKS A ND F A CILITIES  
Troutdale P arks  and F acilities  will  be  charged  with  the m aintenance  of  the  observation  
deck a s  well  as  the r est  of  the  park  once  it i s c omplete.  There  are c urrently s ix  city  
employees i n  this o ffice i ncluding  a  superintendent,  a m aintenance t echnician, a nd f our  
park  maintenance p ersonnel. T heir  input  will b e c onsidered  when  determining  the t ype  
and f requency o f m aintenance f or  the  observation d eck.  
  
1.2.6 E N D  US ERS  
The e nd-users  for t his p roject  will  be  the v isitors  who  utilize  the  observation  deck  for  
recreation  and  leisure.  This i ncludes p edestrians, b icyclists,  and a nybody u tilizing  the  
river  itself  for f ishing,  kayaking, o r o ther  activities. A s a  p ublic w orks  project,  the  end  
users’  enjoyment  and  access  to  the a rea i s a  p rimary g oal.  
  
   
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Troutdale O bservation  Deck ( 2021.TROUT.03) 2021  
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2.0 A L TERNATIVES  AN ALYSIS  
The c lient, t he  City  of T routdale,  has  identified  their p reference  for a  c antilevered d eck  design. I n  
order t o  evaluate t he  viability  of d ifferent  deck d esigns,  an a lternatives  analysis  was u tilized. F our  
designs  were c ompared, a long  with a  c ontrol  “No  Build” o ption, u sing  seven w eighted c riteria a nd  
a 1 -5 s core  per c riteria.  The  two h ighest-scoring d esigns  were p resented  to  the  client  for a pproval.  
  
This s ection  is d ivided i nto  four s ubsections:  Alternatives C onsidered, C riteria D escriptions,  
Alternative  Scoring, a nd  Preferred A lternative, w herein t he  components  of  the  alternative a nalysis  
will  be  elaborated  upon i n  detail.  
  
2.1  AL TERNATIVES  CO NSIDERED  
PSU  CEE  Capstone p roposed a   total o f f ive a lternatives, i ncluding  a  no-build o ption.  These  
alternatives  took i nto  consideration  the  size, l ocation,  user  experience, a nd p ublic  service  
requirements t hat  the c lients r equested, a s w ell  as f uture  maintenance.  The a lternatives  were  
then  presented  and a djusted p er  client c omments, a nd  the  Pugh  matrix w as u sed  to  evaluate  
and  score e ach a lternative.  
  
2.1.1: L arge  Cable-stayed D eck  
This  design  focuses  on a  c able-stayed s tructure w ith  a  large  deck ( Figures 2 .1, 2 .2).  
Smaller,  intermediate  foundations  will  be  utilized.  Foundations  will b e  a  combination o f  
grade b eams, p iles, a nd p ile c aps w ith a  p ost-tensioned d eck.  The d eck  will s pan  the  Sandy  
River. T his  design  is  suitable  for  multiple l ocations. I t a lso  allows  the o bservation d eck  to  
be  a  visual  attraction  for t he c ommunity  and t akes  full a dvantage  of t he s pace  and  view  of  
the  river.  
  
Figure  2.1: P lan  view  of t he p roposed  large  cable-stayed d eck  design  
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Figure  2.2:  Profile  view o f t he p roposed l arge  cable-stayed  deck d esign  
  
2.1.2: L arge  Cantilever  Deck  
This d esign  focuses o n a   large  cantilevered d eck  (not  cable-stayed) ( Figures 2 .3,  2.4).  This  
option w ould  require  the  largest  foundation,  consisting o f p iles  and  tie-back a nchors. T he  
deck w ill s pan  over  the S andy  River. T his d esign  is s uitable  for m ultiple  locations.   
  
Figure  2.3: P lan  view o f t he p roposed  large c antilever  deck  design  
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Figure  2.4:  Profile  view  of  the p roposed l arge  cantilever  deck d esign  
  
2.1.3: S mall  Cantilever  Deck  
This d esign  focuses  on u tilizing a  c antilevered d eck w ith  a  smaller,  intermediate-sized  
foundation t o  improve e conomy  and  sustainability  (Figures 2 .5,  2.6).  The f oundation  will  
use  piles  and  the  deck w ill b e s upported o n  cantilevered j oists.  The  deck w ill  span t he  
Sandy R iver. T his  design i s  also s uitable f or m ultiple  locations.  
  
Figure  2.5: P lan v iew o f t he  proposed s mall  cantilever d eck  design  
  
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Figure  2.6: P rofile  view o f  the p roposed s mall c antilever  deck  design  
  
2.1.4:  Wide  Shallow  Deck  
This a lternative c onsists o f a  l onger  and  thinner d esign t hat f ocuses  on e conomy a nd  
efficiency i n m ultiple  aspects  of  the d esign ( Figures 2 .7, 2 .8).  It  will  utilize  a  series o f  
cantilever b eams t o s upport  the d eck.  The  foundation w ill  include p iles/micro p iles. T he  
platform  to  foundation r atio  will b e 1 :1:5  (Deck:Foundation w idth:Foundation l ength). I t  is  
suitable  for a ny  location  chosen. T he  foundation  dimensions a re  subject  to c hange b ased  
on  the  structure’s l ocation.  
  
Figure 2 .7:  Plan  view  of  the  proposed w ide  and  shallow d eck d esign  
  
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Figure  2.8:  Profile v iew  of  the  proposed  wide  and  shallow  deck  design  
  
2.1.5 N o  Build O ption  
This a lternative a ims  at  keeping t he s ite  in  its c urrent  condition w ithout  any f urther d esign.  
See F igures  2.9 a nd 2 .10 b elow  for c urrent  site  conditions.  
  
Figure 2 .9: D rone  photo  of c urrent  site  conditions  from   
above  Sandy  River  looking s outheast  
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Figure  2.10:  Aerial v iew o f c urrent s ite c onditions  
  
2.2 C  RITERIA D E SCRIPTIONS  
The  criteria  development s tarted  out w ith e ngineering p roposals  in  the  form o f a   Pugh  Matrix.  
These  criteria  focused o n r epresenting  the c lient’s  requests f or  the  design.  The  final  criteria  
descriptions w ere  presented  to  and a pproved  by t he c lient  before o fficially  being  included i n  
this  report.   
  
2.2.1  Cost   
This c riteria  refers  to t he  overall  cost  of t he s tructure,  including  the  costs  of c onstruction,  
permits,  and  materials. B ased  on t he  City  of T routdale’s r equest, c ost i s a n  important  
deciding f actor  in  the  design o f t he  structure.  The  costs o f  each  design  is i mportant t o  
consider d ue t o t he  public n ature  of t he  funding f or t he  project. A  h igher c onstruction c ost  
will  result i n a  l ower  score  for  this  criteria ( Table  1),  and t his  criteria  was a ssigned  a  
weight  of  9.  
  
  
  
  
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Table 1 : Cost  criteria s coring a nd d escriptions  
Score  Criteria  
1  Most e xpensive  design  
2  Very e xpensive  design  
3  Moderately  expensive d esign  
4  Less e xpensive d esign  
5  Least  expensive  design  
  
2.2.2  Constructability  
The p roject’s  constructability r efers t o t he  probability  of s ignificant  challenges  arising  
during  construction.  Simpler  designs  lead  to  easier  and  faster  builds,  whereas c omplex  
designs  can  create  challenges  that  delay c onstruction s chedules  and i ncrease  costs.  This  
can  lead  to  issues t hat  the  client a nd p roject t eam  need  to  resolve.  Extra  earthwork m ay  
also  be  needed f or  different  designs. E arthwork  includes p ermeability,  corrosion &  e rosion  
protection,  and  foundation  work.  Additional  earthwork  on  a d esign  will r esult  in c hanges  
to t he  schedule  and  increased  complexity  of  construction.  An e asier  design c onstruction  
process  will  produce a  h igher  constructability  score  (Table 2 ),  and  this  criteria  was  
assigned  a  weight  of  6.   
  
Table  2: Constructibility  criteria  scoring a nd  descriptions  
Score  Criteria  
1  Design i s  very  intricate  and  complex w ith  
overwhelming  construction  complications.  
2  Design i s  intricate a nd c omplex  with m any  
complications  in t he  construction.  
3  Design  is m oderately  complex w ith s everal  
complications i n t he c onstruction.  
4  Design  is  mildly  intricate w ith m inor  
complications  in  the c onstruction.  
5  Very s imple  and s traightforward  design  with  
no  complications  in t he  construction.  
  
  
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2.2.3  Environmental  Impact  
Sustainability i s  important i n t he  design,  including t he  preservation o f  the s urrounding  
natural e nvironment a nd  existing s oil  quality. I t  is v ital t o  minimize  ground  disturbance,  
erosion, r unoff,  and r emoval o f  trees,  as w ell a s  floodplain  impact.  This c an b e  
accomplished b y m inimal-disturbance d esigns a nd  consideration  of t he  design’s l ocation.  
Designs w ith l ower  environmental  impact  will  receive a  h igher s core  (Table 3 ), a nd t his  
criteria  was  assigned  a w eight  of  5.  
  
Table 3 : Environmental i mpact  criteria  scoring  and  descriptions  
Score  Criteria   
1  Severe  environmental d isturbance.  All  or  
majority  of  trees  removed  from  the  site.   
2  High e nvironmental  disturbance.  Substantial  
tree  removal f rom s ite.   
3  Moderate  environmental  disturbance.  
Multiple t rees  removed  from  the  site.  
4  Mild  environmental d isturbance. L ow  
overall  local  environment  disruption.   
5  No  impact  or  disturbance  of  the  local  
environment.  
  
2.2.4  User  Experience  
The  user  experience  score  will  be  based  upon t he f low  of t he  structure  within t he  
surrounding  park a nd  trails,  the  ease  of  access  to t he  trails  and  structure, a nd  the  sound  
pollution  from  both  the  nearby  freeway  and n earby  railroad  bridge.  For  the  purposes  of  
scoring, “ engagement”  will  be  defined  by  the  level  of  positive i nteraction  from  the  public  
and  the  volume  of v isitors.  An  aesthetic  design  is  crucial  for  drawing  visitors  to  the  park.  
This  portion  of  the  criteria  will  be  met  by  designs  with  spatial  aesthetics  and  appealing  
geometry  and s ize.  Alternatives  with a n  appealing  aesthetic a nd  good  user  experience w ill  
receive a   higher  score ( Table  4),  and t his  criteria  was a ssigned  a w eight  of  7.  
  
  
  
  
  
  
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Table 4 : User e xperience  criteria  scoring a nd d escriptions  
Score  Criteria  
1  No  engagement  
2  Mild e ngagement  
3  Moderate  engagement   
4  Substantial  engagement   
5  High  engagement   
  
2.2.5  Resiliency &  S trength  
The  resiliency  &  strength  criteria  will  depend  on  the l ength  of t he  structure’s e stimated  
lifespan,  as  well  as t he  seismic  and  structural  capacity  of t he s tructure.  Any  additional  
reinforcement  that  is r equired  after  completion  of t he  structure  will  lead t o  increased c osts  
and  extended  construction  time.  The  structure’s  ability  to  withstand f loods,  landslides,  and  
wind  and s eismic  loads w ill  also  significantly c ontribute  to i ts  score  in  this  criteria.  
Designs w ith l ess  required a dditional  reinforcement  and  longer  lifespans  will  receive  a  
higher s core ( Table  5),  and  this  criteria  was  assigned a  w eight o f  8.  
  
Table  5: Resiliency  and  strength  criteria s coring a nd  descriptions  
Score  Criteria  
1  Shortest  lifespan/requires  most  additional  
reinforcement  
2  Short l ifespan/requires  more  additional  
reinforcement  
3  Average l ifespan/requires s ome  additional  
reinforcement  
4  Long  lifespan/requires  little  additional  
reinforcement  
5  Longest l ifespan/requires n o a dditional  
reinforcement  
  
  
  
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2.2.6 M aintenance 
The  client  has  made i t  very c lear t hat t he  long-term  maintenance  of  the  structure i s  an  
important  part o f  choosing  an a lternative. T he m aintenance  score w ill  be  based  on  how  
often e ach a lternative  will  need t o b e  replaced a nd/or  cleaned.  This  score  will  also t ake  
into  account h ow i ntensive  the  maintenance  will  be.  Alternatives  with  high m aintenance  
will  receive  lower s cores ( Table  6), a nd t his  criteria w as a ssigned  a  weight o f 9 .   
  
Table  6: Maintenance  criteria s coring  and d escriptions  
Score  Criteria  
1  High  Maintenance   
2  Substantial   Maintenance  
3  Moderate  Maintenance   
4  Mild  Maintenance   
5  No  Maintenance  
  
2.2.7  Permitting  
The  complexity  of  the d esigns w ill  determine  the  permitting  that  is  necessary  for  each  
different  alternative.  Increased p ermitting r equirements  could  significantly  raise  the c ost  
and d uration  of  a  project.  The  designs  with  simpler  permitting r equirements  will  receive  a  
higher s core  (Table  7),  and  this  criteria  was  assigned  a w eight  of  8.  
  
Table  7: Permitting  criteria  scoring  and  descriptions  
Score  Criteria  
1  High  Permitting  
2  Substantial P ermitting  
3  Moderate  Permitting  
4  Mild  Permitting  
5  No P ermitting  
   
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2.3  AL TERNATIVE S  CORING  
Each o f t he a lternatives w ere  scored  based  on t heir  cost,  constructability,  environmental  
impact, u ser  experience, r esilience &   strength, m aintenance, a nd p ermitting. T he  scoring w as  
completed  by c omparing  the c riteria  descriptions  above  with  each  alternative’s  proposed 
design.  
  
2.3.1 P ugh M atrix  
  
Table  8: P ugh  Matrix  Alternative  Analysis  
CRITERIA  
ALTERNATIVE  User  Resiliency  
Construc Environmenta 
TITLE &   Cost  Experienc and  Maintenance Permitting tability  l  Impact  
DESCRIPTION  e  Strength  
1)  Large D eck,  1  1  3  5  5  4  3  
Cable-Stayed  
2)  Large D eck,  2  2  3  4  2  1  3  
Cantilevered  
3)  Small C antilever  4  3  3  2  3  2  4  
Deck  
4)  Small D eck,  Wide 3  4  4  2  4  3  4  
and  Shallow  
5)  No-Build  5  5  5  1  5  5  5  
CRITERIA  
WEIGHTS  9  6  5  7  8  9  8  
  
Table 9 :  Pugh M atrix A nalysis R esults  
Order b y  
ALTERNATIVE  TITLE  &  TOTAL  score  
DESCRIPTION  SCORE  (high-low)  
1)  Large  Deck,  Cable-Stayed  165  2nd  
2) L arge  Deck,  Cantilevered  122  4th  
3) S mall  Cantilever D eck  157  3rd  
4)  Wide a nd S hallow  Cantilever   176  1st  
5)  No-Build  232  N/A  
   
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2.3.2 L arge  Cable-stayed  Deck  
The  cable-stayed  deck  design  is m ore  unique  and a mbitious t han t he  other  designs. T he  
cable-stayed a spect  of  the d esign  means  that  it h as  a c ostly a nd c omplicated  construction,  
which i s  reflected i n v ery  low  scores  for t he  cost a nd  constructability c riteria. H owever,  the 
increased  cost  and  complexity  of  the d esign r esults  in a  m ore  resilient  structure t han  the  
other a lternatives.  It  also  has a  s ubstantially b etter-proposed  user e xperience b ecause t he  
design  will a llow f or  the  deck  to b e  suspended  over  the r iver.  This, c ombined  with  the  
post-tensioned  deck,  will  contribute  to a n i mpressive  visual  experience. B ecause  the  design  
requires  more s pace, i ts  impact  on  the s urrounding  environment  will  be g reater  than t he  
other  alternatives. M aintenance i s  expected  to b e  moderately d ifficult  because  special  
equipment w ill  be  required t o  access  the v ertical  elements  of t he  structure. T he  amount  of  
permitting  required f or t he p roject  is  significant  and  also c omparable t o t hat o f  the l arge  
cantilevered  deck.  
  
2.3.3  Large C antilever  Deck  
This  design  consists  of a   large d eck  with  deep f oundations. T he c ost o f  construction a nd  
design  complexity  is s ignificant,  which r esults i n  this a lternative’s c ost a nd  constructability  
scores c oming i n s econd  to t he c able-stayed  deck.  However,  the  larger  deck  size  and  
proximity  to  the r iver c ontribute t o a  h igher u ser e xperience  score.  This d esign’s s ite  
footprint  is o n p ar  with  that o f t he  cable-stayed  deck,  leading  to a  s imilar  score  in  
environmental  impact.  As t he  structure  is s upported  solely b y  a  cantilever, a dditional  
reinforcement, f requent  inspections,  and r outine  repairs  are  to b e e xpected.  The a mount o f  
permitting  needed  is s imilar t o  the c able-stayed  deck, r esulting  in  a  tie b etween  the t wo  
designs’  scores.  
  
2.3.4 S mall  Cantilever  Deck  
The s mall s ize  of t his c antilever d eck  design e mphasizes t he  structure’s  ease  of  
construction  and  maintenance. F ewer  materials, s maller c onstruction  costs, a nd  less s ite  
impact  are  also  a  result o f  the s tructure’s s maller s ize.  The  simple s tructure i s a lso  
forecasted t o r equire  fewer p ermits  and l ess  frequent m aintenance. H owever,  the s mall  size  
is  less  capable o f h osting  visitors t han  the  larger a lternatives c onsidered  and w ill  not  
extend  over t he w ater.  
  
2.3.5  Wide a nd S hallow  Cantilever  
This  design  features  a  short  but w ide c antilever d eck  contouring  along  the  trail  alignment.  
The  wide  structure l ends  less t o a n i mpressive  user  experience b ut  its  proposed  location  
compliments a  r est a rea d irectly  across  the t rail. I ts  simplicity a nd s hort  cantilevered l ength  
make t his a lternative  much  easier t o  build,  resulting i n a  h igher c onstructability s core.  The  
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quantity o f  materials  required  for t his s tructure i s g reater t han  the o ther s mall c antilever  
design. T he  degree  of  environmental  disturbance  is l ess t han t he o ther a lternatives,  which  
leaves  room  for  future l andscaping  to a ssimilate t he  deck i nto t he p ark’s l andscape.  
  
2.3.6 N o B uild   
The n o-build  option  intuitively  scored  the  greatest.  These s cores  reflect  the f act t hat  if  we  
simply  leave  the  site  as  it  is t hen t here w ill b e n o  cost,  no  constructability  score,  and  no  
foundational  work  or e nvironmental  impact. O n  the o ther  side  of  the s pectrum, t his o ption  
scored p oorly i n t he a esthetics a nd c apacity  criteria.  Without m aking  changes  to  the  site  it  
will r emain  as  an e mpty l ot.  The m aintenance s core i s a   nine d ue  to  the f act t hat c urrently,  
the c ity d oes  try  to m aintain  the  site  to s ome  degree b y p lanting  grass  seed  and  keeping  
pathways c lear o f d ebris.  Currently, t he s ite  has  a  low  user  experience s imply  because  it i s  
being u sed  as a  f risbee g olf c ourse  and l eaving t he s ite  as  it d oes  not  affect t he  floodplain  
at  all.  
  
2.4  PR EFERRED A L TERNATIVE  
After c alculating  the w eighted  total f or e ach  alternative, d esign A lternative  #4, t he  Wide  and  
Shallow C antilever,  scored  highest  behind  the  No  Build o ption. T he f inal  recommendation f or  
the  client  is  the W ide a nd S hallow  Cantilever d esign  because  they a re  not c onsidering  the N o  
Build  option a t t his  time.  
  
The  client  presented  the P ugh  Matrix a nd t he r ecommended  design t o s takeholders. T he 
preferred  alternative c hosen b y  the  stakeholders w as A lternative  #4,  the  Wide  and S hallow  
Cantilever b ecause  it i s  small  and  aesthetically c omplements  the p lanned t rail  design.  
  
After p resenting  the  Alternative  Analysis  from P SU C apstone  Team t o t he  Public C ommittee  
of  the  City  of  Troutdale. T he  City  of T routdale d ecided  to  proceed  with  this  alternative t o t he  
30%  design  phase.   
  
  
   
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3.0  FA CILITY  DE SIGN  
The  following s ubsections o utline  the  different e lements  comprising  this  proposed  30% d esign.  
These s ections i nclude  Design  Summary ( Section  3.1), S tructural D esign  (Section 3 .2),  Standards  
and  Specifications  (Section 3 .3), G eotechnical D esign ( Section  3.4), C alculations  (Section 3 .5),  
AutoCAD  (Section  3.6), a nd C onstruction  (Section  3.7).  
  
3.1  DE SIGN S  UMMARY   
The  proposed  design A lternative  #4  (Small D eck  Wide  and  Shallow) w ill  be  constructed  of  
pultruded f iberglass  decking  (Fibergrate’s S afe-T-Span®  Pultruded  Grating o r e quivalent). T he  
deck w ill  be  cantilevered 1 7’  from  its  support a nd h ave  an o verall w idth o f 1 8’. T he  fiberglass  
decking  will  be s upported b y s ix s teel g irders  placed p erpendicular t o  the c antilever  length  and  
spanning t he  full  18’  width.  These  steel g irders w ill t hen b e s upported b y  two r einforced  
concrete  beams  parallel  to t he  cantilever  length a nd l ocated a t o pposite  sides  of t he d eck.  
These  beams  span t he  17’  cantilever  length, a s  well  as  a  back s pan  of  1.5 t imes  the c antilever  
length -   equalling 2 5.5’.  The  back s pan  will  be u nderground  with  the p urpose  of 
counterbalancing  a  portion  of t he w eight  on t he  cantilever  side o f  the  deck.  
  
The d esign w ill h ave i ts  centerline  located a t  station 6 +30 a long  the p lanned t rail a lignment.  
This t rail  is  featured  in  the  Marianne  Zarkin  Landscape A rchitects  30%  Design P lan a nd  
contains  the b ase f iles  utilized f or  drafting.   
  
3.2 S T ANDARDS A ND S  PECIFICATIONS   
The  specifications  and s tandards u sed  for  calculations  and c onstruction w ill  be  included i n  this  
section. T his  includes  ORSS, A STM, A ASHTO,  TDT  and O DOT  Bridge  Design.   
  
3.2.1  ORSS ( 2019)   
The O regon  Structural  Specialty C ode  Section  1607 c ontains T able 1 607.1,  which f eatures  
a  series o f  different u niform a nd  concentrated  live l oads  to b e a pplied  to a   structure b ased  
on  its  occupancy o r u se.  
This  project u tilizes  the  loading  for  Exterior F oot  Bridge,  with  100  psf a nd 1 000-pound  
pedestrian  live  loads. T hese l oads w ere s elected  to  align w ith  the a pplied v ehicle l oading  
from  the A ASHTO P edestrian B ridge D esign.  
  
3.2.2  ASTM  A6  
ASTM  A6  contains  dimensions  and  parameters  for w ide f lange s teel  W  beams.  This  
section i s u tilized i n  the  steel  stringer d esign.  
  
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3.2.3 A ASHTO  
The  2009 e dition  of  the  AASHTO L RFD G uide  Specifications  for  the  Design  of  
Pedestrian B ridges  was  used t o  incorporate m aintenance  vehicle  loads i nto t he  structural  
design. S ection  3.2  contains  discussions o n v ehicle l oading,  and  Table  3.2.1 c ontains t he  
vehicle  axle  loads a nd  geometry. T here  were t wo o ptions  for  design l oads  based  on t he  
clear  deck w idth.  For  this  design w ith  a  clear w idth  of  18’,  the  H10 d esign  maintenance  
truck g eometry  and  loads  were  utilized.  
  
3.2.4  Troutdale  Development C ode  (TDC)  
The  Troutdale D evelopment C ode  is a  s et o f s tandard  details  and g uidelines  to  follow  
when  installing  or  constructing  something  in  the  City  of  Troutdale.  The  TDC ( Troutdale  
Development  Code, 2 019) i s  primarily  used  by  construction w orkers  and i s  often r eferred  
to i n  plan s ets.  
  
Flood m anagement c odes n eed t o b e m et  due t o t he s tructure’s  location  on  the  bank o f t he  
Sandy  River,  which  may  be a ffected d uring f lood s torms.  These  codes  ensure  that  public  
health, s afety, a nd g eneral w elfare  are  maintained  during f lood c onditions ( Troutdale  
Development C ode,  2019).   
  
3.2.5 O DOT B ridge D esign  
The O regon D epartment  of T ransportation p rovides  standard  drawings f or b ridge d esign,  
and t he B R700  series f eatures  retaining  wall s tandards.  For  the p urpose  of t his  30%  design,  
the  BR709 C ast-In-Place S emi  Gravity  Retaining W all  standard  drawing.  
  
   
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3.3 S T RUCTURAL D E SIGN  
Structural d esign o f O bservation  Deck  includes: c oncrete g irder  design,  steel  stringer d esign, 
and  fiberglass p ultruded  decking. A  r etaining  wall  is r ecommended  and  a  standard  design  by  
Oregon D epartment  of T ransportation i s a lso  included.  The  design  criteria  satisfy s afety  
requirements,  aesthetics, a nd  long-term  ease o f a ccess  maintenance.  Design  criteria f ollow  
stipulated s pecifications  as  required b y t he  State  of O regon  and t he C ity  of T routdale. D etailed  
design  criteria a re  described i n  the  following  sections.  For t he  general  load c alculations  
applied  to t he d eck, p edestrian  live  loads w ere s elected f rom  ORSS  Table  1607.1  and a   
maintenance  vehicle  load  from S ection  3.2 i n  AASHTO B ridge  Design. F or  these d eck  load  
calculations, s ee A ppendix  D1.  
  
3.3.1 C oncrete G irder  Design  
The c oncrete  girders  were  designed  to r esist t he l oading  from t he  steel s tringers  and t he  
live l oads. F or t he  live  loads, a  m oving  load  analysis  was p erformed  of  a  100  psf  
pedestrian  load f rom  and a  v ehicular l oad  of a n H 10 d esign  vehicle.  The l oadings  were  
analyzed  in a  s tructural  analysis  program  called  SAP2000  to o btain a   maximum b ending  
moment  and a   maximum s hear.  In  order t o  provide t he s trength t o r esist t he l oading, a  3 0”  
by  18”  beam w as  chosen w ith 6  # 10 b ars i n t he t op s teel, 2  # 10 b ars  in  the  bottom  steel,  
and  #4  stirrups  spaced  at 1 2  inches.  The g irder p rovides a  d emand t o c apacity r atio  of  0.73  
for  the b ending m oment  and 0 .69  for  the  shear. T he g irder's  stirrup d etailing  needs t o b e  
further  examined;  the  30%  design o nly c onsidered d esigning  for  shear  capacity a nd  did  not  
consider  the s tirrup s pacing  design.  See  Appendix D 2  for t he a ssociated c alculations  sheet.  
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Figure  3.1:  Schematic  of s tructural  design  
  
Figure  3.2:  Design l oad  distribution  
  
Figure 3 .3:  Loading  distribution  modeled  in S AP 2 000  
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3.3.2 C oncrete R etaining  Wall  Design  
  
The B R709  Cast-In-Place  Semi  Gravity  Retaining W all  standard d rawing w ill b e  utilized  
in  the  design. T he w all  will b e a   standalone s tructure  and  placed j ust b ehind  the  beginning  
of  the c antilever. T he  design  is i n  compliance w ith O DOT  Bridge D esign  Standard B R705  
and B R706.   
  
3.3.3  Steel  Stringer  Design  
  
The s teel s tringers  are  designed  assuming  six 1 8 f t l ong  steel  girders, s paced 3 .4  ft o n  
center. U nder  this  geometry  and w orst-case H 10  design  vehicular l oading, t he  factored  
loading  includes  a  distributed  load  of  302 p lf, a  p oint  load o f 1 4.4 k ips,  and  a s econd  point  
load  of 1 2.8  kips.  The  placement  of t he p oint l oads  varies  with  each  limit s tate  to  
maximize  internal  girder f orces  or  deflection.  The  specified W 10X54  provides a   demand  
to  capacity  ratio ( D/C) o f 0 .92 f or f lexural  torsional  buckling. S hear  and  bending  do  not  
control t he  design  and  provide D /Cs  of  0.31 a nd 0 .47, r espectively. U nfactored  service  
loads m eet  serviceability  deflection c riteria  per  ORSS  1604.3.3. P lease  see  Appendix D 3  
for  further d etails.   
  
3.2.4 P ultruded F iberglass D ecking  
  
The m aterial  chosen f or  the  decking i s  the H I3730 p ultruded f iberglass. T his  is  the  high  
load c apacity  grating  offered  by f ibergrate  that i s c apable o f  supporting  AASHTO  vehicle  
loads. T he  material c hosen  by o ur t eam i s a ble t o w ithstand l oads o f  an  H10 v ehicle a t  a  
span  of  3’-6” w ith  a  30% i ncreased  impact r ate a nd a   factor o f s afety  of 3 .0. T he  
deflection  under  max  loading  conditions i s b elow 0 .25  inches w hich  is b elow  the  
deflection  code l imits. O n t op o f t hat,  it  is  ADA c ompliant w ith  an o pen a rea o f  only  37%.  
For d eflection c alculation,  see  Appendix  D4   
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Figure  3.4: P ultruded  Fiberglass M aterial  
  
3.4 G E OTECHNICAL  DE SIGN  
The  geotechnical  assumptions,  data,  methods o f c alculation, a nd  results  are  included i n t his  
section,  along  with  a  description o f  the  site’s  geotechnical c onditions a nd  design f oundation  
recommendations.  See  Appendix  E  for  calculations, f igures, a nd  plan  set.   
  
3.4.1  Current  Site  Conditions  
The s cope o f  the c urrent  site’s s oil i nformation  has  been  created  using a   nearby  hand  auger  
and  boring  logs f rom  the G RI G eotechnical  Investigation  for t he  Sandy  Riverfront  Park.   
The p roposed l ocation f or t he c antilevered o verlook f alls  between 2   sets  of  auger l ocations  
and s ome  distance f rom  one o f t he b oring l ogs,  hand a uger l ocations  4/5 a nd 6 /7,  and  
boring  log  B-1.  This  means  that  the  foundation  design f or  the p roject w as c ompleted u sing  
data  that i s n ot c ompletely  representative o f  the s oil  profile a t t he e xact l ocation  of t he  
overlook.  For  the  30%  design w ork  found i n  this  report, t his  was  determined  to b e  
acceptable. H owever, f or a   complete d esign o f  the S andy  Riverfront O verlook,  a n ew h and  
auger  and  boring s amples s hould  be  taken i n t he l ocation  of t he  project s ite. C PT  and  SPT  
testing  methods  should  also b e c onsidered.  
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Figure 3 .5:  Current s ite  condition  soil  conditions g roundwork  for  geotechnical d esign  
  
The  site w as  found  to  have a   variable f ill t op-layer,  clay/sand/silt m id-layer,  and  a  
gravel/cobbles b ottom-layer u sing t he a vailable s oil i nformation.  The  focus  of t he  
foundation  design  of  this p roject i s o n t hese t hree l ayers o f  the  soil p rofile f rom  boring l og  
B1.  The  upper  variable f ill  layer  reaches a   depth  of  twenty f eet a nd c onsists o f  different  
structural  fills  including s ilty s ands  containing  organic  materials a s  well  as  gravel a nd  
cobbles. T he  middle l ayer i s m ade u p o f 2 2 f eet  of s ilty c lay a nd s and,  this l ayer a nd t he  
silty  fill p ortions o f t he  upper l ayer  are  moisture  sensitive  and  therefore e asily d isturbed  
during  construction i n  wet w eather.  The  final l ayer i s m ade  up o f 3 3 f eet  of  gravel  and  
cobbles w hich  is w hat w e  used a s a   reference  of  how d eep  our p ile  foundation  would n eed  
to  go  given  the  stability o f t he  layer.  The  GRI r eport  recommends  the  use  of  a  spread  
footing f oundation  for  the c antilevered p ortion o f  the o verlook.  This  design w as  looked  
into  initially b ut d eemed  insufficient f or  our  design. T his  led  us t owards  the u se o f  deep  
piles  which  could  reach t he l ower a nd m ore s table s oil l ayers.  
  
The  GRI  geotechnical  report b rought  up  a s ignificant c oncern  related t o  the  soil  profile f or  
the p roject s ite. B ased o n t he r eport, t he s ilty  soils  in t his  area  are e xtremely m oisture  
dependent a nd  could  be u nsuitable  fill f or t he p roject. T his  would r equire  extra  soil  
excavation  to  replace  the  silty s oil f ill w ith  a m ore  stable s tructural f ill.  This i ssue d epends  
heavily o n t he  time a nd  weather c onditions d uring c onstruction. I f  construction t ook p lace  
in d rier  months, i t  would p ose  less  of a n  issue t han b uilding  during t he w etter m onths l ater  
in  the  year.  
  
  
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3.4.2 D eep  Pile  Design A ssumptions  and M ethods   
In  calculating  the d imensions n eeded f or  the d eep  pile f oundation, t he  following  
assumptions w ere m ade:  The l oad o n  the  cantilevered  section o f  the  overlook i s a   uniform  
area l oad,  there  is n o b earing c apacity i n t he h orizontal d irection,  there i s  a f actor  of s afety  
of t hree, a nd  that  the  soil p rofile f rom  boring B -1  of  the G RI g eotechnical r eport i s  similar  
to  the  soil p rofile a t  the p roject  site. T he  final  assumption  made  regarding  the  soil  profile  
was u sed  because  the  project  site  is a pproximately f ive  hundred f eet  from  the  closest  
boring s ite,  B-1.  To  make  up f or  any  differences  in t he  soil p rofile o f t he p roject  site  and  
the b oring  log u sed f or t he d esign, t he c alculations  for  the  deep  piles w ere d one  
conservatively.   
  
Figure  3.6:  Schematic o f  the  deep  pile d esign f or O bservation D eck  
   
The c urrent  method  is  using  the  bearing c apacity o f d eep p iles  in t he l owest l ayer  of  
cobbles  and  gravel b eginning a t  a  depth  of f orty  two  feet. T his t akes  into a ccount  the 
loading  and  moments  on t he s tructure,  the  effective b earing  angle, t he u nit  weight  of t he  
soil,  and m any  other  factors  that  can  be s een o n t he t able.   
  
3.4.3 R ecommendations f or F uture D evelopment  
Based o n t he a vailable  data,  we r ecommend  that f urther s ubsurface e xploration  be  
conducted  at t he  site.  CPT  and  SPT  sampling  should b e  considered. T he c urrent  design i s  
based o n  information p rovided  by t he  GRI  Geotechnical  report,  where  the m ost  relevant  
data w as f rom  the B 1 b oring l og.   
  
Collecting  samples f or  laboratory a nalysis  is  also r ecommended i n  order  to  provide  further  
information  about t he  local s oil’s  engineering p roperties. L aboratory  results c an  help t o  
determine  if  the n ative s oils  are s uitable f or u se i n  construction o r  not.   
  
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3.5  CA LCULATIONS  
Structural  calculations  done  for O bservation D eck t ook i nto  account t he  stability  of t he  
structure u nder d esign l oads a s  well a s  service  life  and  maintenance  ease-of-access. P SU  
Capstone  Team  used t he O regon  Structural S pecialty C ode f or  allowable d eflections ( ORSS  
1604.3.3)  and a pplied  pedestrian l ive  loads ( ORSS 1 607.1-36), t he  2009 A ASHTO L RFD  
Guide S pecifications  for  the D esign  of P edestrian  Bridges  for  vehicular  loading ( AASHTO  
3.2-1, 2 009),  American S ociety f or  Testing  and M aterials  specifications  for  wide f lange  steel  
beams ( W b eams) t hat  offers h igh  flexural s trength ( ASTM  A6), A ASHTO S oil  
Classifications  system,  and  The  Troutdale D evelopment  Code  (TDC).  Please  see  Appendix  E 
for  detailed c alculations.   
  
3.6  VI SUAL  AI DS A ND  CO NSTRUCTION D R AWINGS  
Visual  aids a re  instructive i mages  including s ketches,  aerial p hotos, a nd  drone  photos  with  
minimal  mark-ups  to s how  details. T he P SU  Capstone T eam  used  the  sketching  software  
SketchUp  to s howcase t he  conceptual d esign a nd  presented  it  to  the  City f or a pproval.  
Construction d rawings f or  the  design w ere  drafted  using A utoCAD C ivil  3D. P lease  see  
Appendix  C  and  D  for  more i nformation.    
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3.6.1  AutoCAD C ivil  3D  
Planning d esign d rawings w ere  done  using  AutoCAD  Civil  3D.  The p urpose  of  the  
drawings  was  to s pecify  detailed  views  of t he s tructure  for  approval a nd  construction.  
Please s ee A ppendix  D  for  the  plan  sets.   
  
3.6.2 S ketchUp   
SketchUp  Pro 2 021 w as t he  3D m odeling  software u sed t o  draft a  c onceptual o verview o f  
the  proposed d esign,  including  the  cantilever d eck  and  the s urrounding  landscape  after  
construction. T he v ersion o f  SketchUp  used  was a   trial  version,  and  as  such t here w as  
limited  access t o c omplex  tools a nd f eatures. T hese  led t o  difficulties  that  the  SketchUp  
drafting  team f aced  when  modeling t he  structure a nd a dding m ore  realistic  graphics.  
Accurately r epresenting  the  landscape  of  the  site, a cquiring  ideal  material  textures,  and  
laying i n c onceptual e ntities  like p lanters  and  pedestrians w ere  the k ey m odeling  
components  that w ere  impacted  by  trial  version  challenges. T he p rocess o f b ecoming  
familiar  with S ketchUp, d rawing,  and  then  designing t his p roject, t ook o ver 1 5 h ours u ntil  
a  complete  structure  model  was f inalized.   
  
3.7 C O NSTRUCTION   
The c onstruction  scheduling p rocess a nd  cost e stimate o f t he  proposed  design i s h eavily  
dependent  on t he  permitting  process. T he  permitting  process  requires a  l onger p rocessing  
timeline  due t o a n  extensive p re-application  process f or m unicipal  land  use  and  building  
permits. A ny c hanges  relating  to  site g rade, c ontours, f loodway b oundaries, a nd o verall d esign  
will f urther  lengthen t he  construction  schedule.   
  
  
3.7.1 C onstruction  Cost E stimate   
The d etailed  construction  cost e stimate s ummary c an  be f ound  in  the  appendices  and  
includes p roject c oordination,  surveying, g eotechnical  investigation, s ubstructure  and  
superstructure m aterials,  sediment  control d uring c onstruction, a nd f inal  stabilization.  
Preliminary c onstruction  cost e stimates  sum  to  $546,180.00,  not  including  general  
contractors  overhead a nd  profit.  Please  see  the C ost  Estimates  spreadsheet i n t he  Appendix  
for  more i nformation.   
  
3.7.2  Construction  Schedule   
The c onstruction  schedule  was  estimated t o t ake a pproximately s even m onths  to c omplete.  
This  process  includes: p ermitting,  earthwork,  foundation  works,  deck i nstallation, a nd  
inspection. T he  permitting p rocess  requires T he S tate  of  Oregon a nd  City  of T routdale’s  
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approval. T he p ermitting p rocess  could  take  between  two a nd f our m onths d ue  to l and  use  
and  building p ermit  pre-application  and  submittal  review p rocesses, w hich  can b e  
complicated  by a ny  floodplain  management  requirements. P lease s ee  the  Construction  
Schedule  in A ppendix  B f or  more i nformation.   
  
  
   
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4.0  RE GULATORY  CO MPLIANCE A ND  PE RMITTING  
The  Observation D eck  design  and c onstruction  involve  the f ollowing  permitting:  construction  
stormwater  general  permit,  flood  hazard  permit  (FEMA  floodplain  management),  land  use  
application, w etlands/waterway r emoval-fill.  This i s  due t o t he O bservation  Deck l ocation  
belonging t o  the p ublic  land a nd  near  a F EMA l ine. T he r equirement  of  permitting  is s ubject  to  
change i n a ccordance w ith t he d esign o f  the  structure  and f oundation.  The  processing  time  for  
each  organization i s a s f ollows,  Oregon D EQ  (48  days),  Troutdale  (63  days)  and  Oregon D SL  
(120 d ays).   
  
4.1  OR EGON D EQ:  CO NSTRUCTION  S TORMWATER  GE NERAL  PE RMIT  
The  Observation D eck s tructure  is a n  outside  structure w ith  rainwater d irectly  falling  off  
from t he s tructure  to  the s tormwater i nlet.  A  permit i s r equired  for  any  outside  structure  
with  water c onveying t hrough. T he  permit  has a n a pplication p rocess  through t he  
Department  of E nvironmental Q uality l ocated i n P ortland,  Oregon.   
  
4.2  TR OUTDALE:   FL OOD  HA ZARD  PE RMIT , L A ND  US E  PE RMIT  
The  location  of t he  Observation D eck  is w ithin  the F lood  Management  Area m apped  by t he  
Federal E mergency M anagement A gency  (FEMA).  The d esign t eam  used t he F EMA’s  
maps F lood I nsurance R ate M aps  (FIRMs) a s  one o f t he b ase m aps f or  design.  The  Flood  
Hazard P ermit i s i ssued  by  the  City o f  Troutdale. A  m ember o f t he C ity’s  representative  
was a lso i n  charge o f  FHP  of  the  City  of T routdale.  The  design a imed f or T ype I   Permit f or  
general c onstruction  without t riggering a ny  further t ypes  of  the  type.   
  
The  Land  Use A pplication p ermit  involves a ll p rojects w ithin  the l imit o f  the C ity  of  
Troutdale.  This  permit  involves  a  flood  hazard p ermit,  development p ermit, s ite  
development r eview,  tree r emoval p ermit, t emporary u se p ermit, e tc. T he  Planning D ivision  
of t he  City  of T routdale i ssues  the  Land  Use A pplication p ermit.   
  
         4.3  OR EGON  DSL:  WE TLANDS /WA TERWAY R E MOVAL- FI LL  
The S tate  of  Oregon r equires a ny w aterways a nd w etland c onstruction  projects  to  obtain  
permits  and  authorizations p rior  to  construction. T he  authorizations  include  Removal-Fill  
permits  and  Proprietary  waterway  authorizations.  The  Removal-Fill  permits  allow t he  
removal o r f ill a ctivity  in w aterways a nd w etlands o ver f ifty c ubic  yards. O bservation  Deck  
construction s hall  require  removing a nd  filling i nto t he  construction  site.  The  Proprietary  
waterway a uthorizations  for  use o f s tate-owned w aterways  which  are  the  Sandy  River  and  
Storm o utlets.  The O regon D epartment o f  State  Lands  is  in c harge o f  issuing t hese  permits.  
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5.0  CO NCLUSION  
The p roposed d esign h as a n  18’ w ide  by  17’  cantilever d eck,  constructed  out o f p ultruded  
fiberglass  grating p anels. T he  substructure c onsists o f s ix  steel W 10X54 b eams  spaced 3 .4’  
on-center  and s upporting t he d eck,  with  two r einforced  concrete  girders  dimensioned a t 1 8” w ide  
and  30”  in  depth. T he  two g irders  are  placed  at b oth  ends  of  the  18’  width a nd  span t he  17’ 
cantilever  and  25.5’backspan.  A  standalone  retaining  wall i s p laced b ehind  the b eginning  of t he  
cantilever a nd i n  front  of  the s pread  footing  foundation,  which  is a ttached  to t he r einforced  
concrete g irder  backspan.  
  
This  design b enefits  from i ts s implicity m anifested  in i ts $ 546,180.00 c ost t o c onstruct. T he  
structural  calculations  utilized  in  this d esign r eport  include  a c ushion  of e xtra c apacity i n t he  
structure, a llowing  for  future a dditions a nd  design  changes t o t ake p lace  without r equiring  a t otal  
redesign.  
  
There a re  some k ey l imitations  that  inhibit  this  design i n  its  30%  phase  and  will  impact f uture  
work  to  be  done.  The  greatest l imitation  is t he  need f or e xtensive  soil  data n ear  the  site.  Boring  
data f urther t o  the  south  of t he  park  is a vailable, b ut  the  distance  between  the  borings a nd t he  
project l ocation  is  too g reat  to  depend  on  the  boring  results.  For a  m ore a dvanced  and  accurate  
foundation r ecommendation,  further  subsurface  exploration  in t he  immediate v icinity  of  the s ite  is  
critical.  
  
Another l imitation c onsiders  the m aintenance  vehicle l oads o n t he s tructure. A ASHTO’s H 10  
design  maintenance t ruck s pecifies a   rear  axle  load o f 1 6 k ips  and  a  front  axle  load  of 4  k ips.  
These v ehicular  loads  are t he c ontrolling  element i n d etermining t he  model o f  pultruded  fiberglass  
decking,  the s pacing o f s teel  stringers t o m itigate  deck d eflection,  and  the d esign o f  the s teel  
stringers, r einforced c oncrete  girders,  and  spread  footing. T o  prevent  such  conservatism,  future  
designers s hould c onsider p ermanent b ollards  to o bstruct v ehicular e ntry  to t he  deck, t hereby  
disqualifying  the  H10 m aintenance  truck l oads.  
  
The  limitations  described a bove  should  be  the  focus  of f uture  designers  to  ensure  confidence  in  
foundations  and  structural  efficiency.  
  
Aside f rom t he a bove  mentioned d esign  work  and  the  completion o f  this  30% D esign R eport  by  
the  PSU  Capstone  Team, t he C ity o f T routdale  and r elated s takeholders  are t o  provide  suitable  
management  arrangements  for  this p roject;  select a nd  appoint s uitable  personnels;  notify r elevant  
parties  and a gree  to  the  cost p rojected  for  the p roject.   
  
33  
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T routdale  Observation  Deck ( 2021.TROUT.03) 2021  
 Final  Design  Report  
  
RE FERENCES  
City o f T routdale. ( 2019).  “Troutdale  Development  Code.” T routdale, O R.  
  
City  of  Troutdale. ( 2019).  “Troutdale D evelopment  Code, C hapter 1 4  - F lood M anagement.”  
Community  Development,  
<h ttps://www.troutdaleoregon.gov/commdev/page/troutdale-development-code>   (Mar.  4, 2 021).  
  
City  of T routdale. ( 2021). “ Flood H azard P ermit.”  Troutdale, O R,  
<h ttps://www.troutdaleoregon.gov/commdev/page/flood-hazard-permit>   
  
City o f  Troutdale.  (2021). “ Land U se P ermit.”  Troutdale,  OR,  
https://www.troutdaleoregon.gov/commdev/page/land-use-application-form   
  
State  of  Oregon  (2021). “ Department  of S tate  Removal-Fill P ermit.”  
<h ttps://www.oregon.gov/DSL/WW/Pages/Permits.aspx  >  
  
Geotechnical I nvestigation  Sandy  Riverfront  Park,  GRI.  
https://drive.google.com/drive/folders/1Hy34eEb7w4HGe9keZruBVLsw5fhpmluo   
3 4  
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T routdale O bservation  Deck ( 2021.TROUT.03) 2021  
 Final D esign  Report  
  
AP PENDICES  
The f ollowing a ppendices  are a ttached.  
  
A. CO NSTRUCTION  CO ST E S TIMATE  
  
B. CO NSTRUCTION  S CHEDULE  
  
C. DR AWINGS  
  
D. SI TE  PH OTOS  
E. CA LCULATIONS  
  43
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
A PPENDIX A   
CO NSTRUCTION C O ST  ES TIMATE  
 4 4
45
  
  
   
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A PPENDIX  B  
CO NSTRUCTION  SC HEDULE  
   
  49
50
WBS Task Description Duration Start Finish Jun '21 Jul '21 Aug '21 Sep '21 Oct '21 Nov '21 Dec '21 Jan '22
6 13 20 27 4 11 18 25 1 8 15 22 29 5 12 19 26 3 10 17 24 31 7 14 21 28 5 12 19 26 2 9 16 23
1 Site Prep 101 days Mon 6/14/21 Mon 11/1/21
1.1 Permitting/Submittal 30 days Mon 6/14/21 Fri 7/23/21
approval
1.2 City of Troutdale 68 days Mon 7/26/21 Wed 10/27/21
Permitting
1.2.1 Pre-application 23 days Mon 7/26/21 Wed 8/25/21
Process
1.2.2 Land Use/Flood 45 days Thu 8/26/21 Wed 10/27/21
Hazard Permits
1.3 State of OR Permitting 23 days Mon 6/14/21 Wed 7/14/21 75 days
1.4 Erosion Control 2 days Thu 10/28/21 Fri 10/29/21
1.5 Construction Survey - 1 day Mon 11/1/21 Mon 11/1/21
Staking
2 Earthwork 11 days Tue 11/2/21 Tue 11/16/21
2.1 Earth excavation 5 days Tue 11/2/21 Mon 11/8/21
2.2 Pile installation 5 days Tue 11/9/21 Mon 11/15/21
2.3 Construction Survey - 1 day Tue 11/16/21 Tue 11/16/21
Verify
3 Deck installation - 19 days Wed Mon 12/13/21
Structural 11/17/21
3.1 Concrete form and rebar 5 days Wed Tue 11/23/21
11/17/21
3.2 Concrete pour and cure 7 days Wed Thu 12/2/21
11/24/21
3.3 Concrete form removal 2 days Fri 12/3/21 Mon 12/6/21
and surface work
3.4 Steel girder installation 1 wk Tue 12/7/21 Mon 12/13/21
3.5 Concrete beam 0 days Mon Mon 12/13/21
inspection 12/13/21
4 Deck installation - Final 10 days Tue 12/14/21 Mon 12/27/21
4.1 Install FRP decking 1 wk Tue 12/14/21 Mon 12/20/21
4.2 Install railing 1 wk Tue 12/21/21 Mon 12/27/21
5 Punch list items 2 wks Tue 12/28/21 Mon 1/10/22
6 Final inspection 0 wks Mon 1/10/22 Mon 1/10/22
7 Event day/Grand open 0 days Mon 1/10/22 Mon 1/10/22
8 As built survey and plans 1 wk Tue 1/11/22 Mon 1/17/22
9 Project Closeout 0 days Mon 1/17/22 Mon 1/17/22
Critical Slack Rolled Up Critical Split Duration-only External Tasks
Critical Split Slippage Inactive Task Manual Summary Rollup External Milestone
Task Summary Inactive Milestone Manual Summary Deadline
Split Project Summary Inactive Summary Start-only Progress
Milestone Rolled Up Critical Manual Task Finish-only
  
  
  
  
  
  
A PPENDIX C   
D RAWINGS  
  
    
  51
52
  
  
    
  
53
  
  
    
  
54
  
  
  
  
55
  
  
56
  
  
57
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
A PPENDIX  D  
CA LCULATIONS  
   
 5 8
Troutdale Observation Deck 2021.TROUT.03
D1 Deck Load Calculations 06/11/2021
DESIGN INPUTS
Key Assumptions
n R/C 2 [-] Number of R/C Girders
Geometry
Deck Dimensions
B deck 18 [ft] Deck width
L deck 17 [ft] Deck cantilever length
L back 25.5 [ft] Deck backspan length
d deck 3 [in] Pultruded Fiberglass decking depth
Steel Stringer Dimensions
L stringer 18 [ft] Length of steel stringers supporting the decking
d stringer 10.1 [in] Depth of steel stringers supporting the decking
S center 3.4 [ft] Center-to-center span between steel stringers (from Steel Stringer Design)
Reinforced Conrete (R/C) Beams
L R/C 42.5 [ft] Length of  R/C Girder (L deck  + L back )
b R/C 18 [in] Width of  R/C Girder (from R/C Girder Design)
b R/C 1.5 [ft] Width of  R/C Girder
h R/C 30 [in] Height of  R/C Girder (from R/C Girder Design)
h R/C 2.5 [ft] Height of  R/C Girder
AASHTO Design Vehicle Geometry
L veh 14 [ft] Axle-to-axle length of the vehicle
b veh 6 [ft] Tire-to-tire width of the vehicle
Material Properties
p deck 17.7 [psf] Pultruded Fiberglass area weight (Model HI3730)
D1 Deck Load Calculations 1/6
59
Troutdale Observation Deck 2021.TROUT.03
D1 Deck Load Calculations 06/11/2021
γ asphalt 145 [pcf] Asphalt overlay unit weight
t asphalt 0.5 [in] Asphalt overlay thickness (0.5" - 1")
w asphalt 6.04 [psf] Asphalt overlay weight
w steel 54 [plf] Steel stringer linear weight (from Steel Stringer Design)
γ conc 150 [pcf] Reinforced concrete unit weight
Live Loads
AASHTO Design Vehicle Load
Locations measured parallel to the cantilever length, origin at the end of cantilever
P veh 20 [kip] Total design H10 vehicle load (AASHTO Ped Bridge Design Table 3.2-1)
P veh.f 4 [kip] Vehicle load distributed to front axle
P veh.r 16 [kip] Vehicle load distributed to rear axle
x veh.f 14.0 [ft] Vehicle front axle load location
x veh.r 0 [ft] Vehicle rear axle load location
Location measured perpendicular to the cantilever length, origin at longitudinal centerline of deck
y veh 3 [+/- ft] Vehicle load location 
ORSS Live Loads
Locations measured parallel to the cantilever length, origin at the end of cantilever
p L 100 [psf] Pedestrian area live load via ORSS Table 1607.1 36. "Exterior foot bridge"
P L 1 [kip] Pedestrian point live load via ORSS Table 1607.1 36. Exterior foot bridge
x L 0.5 [ft] Pedestrian concentrated live load location
Location measured perpendicular to the cantilever length, origin at longitudinal centerline of deck
y L 0 [+/- ft] Pedestrian concentrated live load location
CALCULATED STEEL STRINGER LOADS
Dead Loads
Exterior Stringers, @ 0' from cantilever end, affected by vehicle load
B Trib.steel 1.7 [ft] Tributary width (end stringer)
D16 0Deck Load Calculations 2/6
Troutdale Observation Deck 2021.TROUT.03
D1 Deck Load Calculations 06/11/2021
w d.steel 94.36 [plf] Total dead load acting on steel stringers
R d.steel 0.85 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
Interior Stringers (3, unaffected by vehicle load)
B Trib.steel 3.4 [ft] Tributary width
w d.steel 134.72 [plf] Total dead load acting on steel stringers
R d.steel 1.21 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
Interior Stringer, @ 13.6', affected by vehicle load
B Trib.steel 3.4 [ft] Tributary width
w d.steel 134.72 [plf] Total dead load acting on steel stringers
R d.steel 1.21 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
Exterior Stringers, @ 17' from cantilever end, affected by vehicle load
B Trib.steel 1.7 [ft] Tributary width (end stringer)
w d.steel 94.36 [plf] Total dead load acting on steel stringers
R d.steel 0.85 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
Live Loads
Exterior Stringer, @ 0' from cantilever start
B Trib.steel 1.7 [ft] Tributary width (end stringer)
w l.steel 170.00 [plf] Lineal live load acting on steel stringers
P l.steel 17.00 [kip] Concentrated live load acting on steel stringers
R l.steel 10.03 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
D1 Deck Load Calculations 61 3/6
Troutdale Observation Deck 2021.TROUT.03
D1 Deck Load Calculations 06/11/2021
Interior Stringers (3 of them, unaffected by vehicle load)
B Trib.steel 3.4 [ft] Tributary width
w l.steel 340.00 [plf] Lineal live load acting on steel stringers
R l.steel 3.06 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
Interior Stringer, @ 13.6' affected by vehicle load
B Trib.steel 3.4 [ft] Tributary width
w l.steel 340.00 [plf] Lineal live load acting on steel stringers
P l.steel 3.53 [kip] Concentrated live load acting on steel stringers (front axle vehicle loads)
R l.steel 4.82 [kip] Reactions at either R/C Girder (symmetrical loading pattern)
Exterior Stringer, @ 17' affected by vehicle load
B Trib.steel 1.7 [ft] Tributary width (end stringer)
w l.steel 170.00 [plf] Lineal live load on steel stringers (pedestrian uniformly distributed load)
P l.steel 0.47 [kip] Concentrated live load acting on steel stringers (front axle vehicle loads)
R l.steel 1.53 [kip] Reactions at one R/C Girder (symmetrical for both girders)
Ultimate Factored Reactions
All locations measured parallel to the cantilever length, origin at the end of cantilever
Exterior Stringer, @ 0' from cantilever start
R d.steel 0.85 [kip] Dead load reaction
R l.steel 10.03 [kip] Live load reaction
R u1 1.19 [kip] LRFD combo #1: P u  = 1.4P D
R u2 17.07 [kip] LRFD combo #2: P u  = 1.2P D +  1.6P L
62
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Troutdale Observation Deck 2021.TROUT.03
D1 Deck Load Calculations 06/11/2021
R u 17.07 [kip] Ultimate Reaction (max of the two combos)
x 0.00 [ft] Steel stringer location
Interior Stringers (3 of them, unaffected by vehicle load)
R d.steel 1.21 [kip] Dead load reaction (same for all 3 stringers)
R l.steel 3.06 [kip] Live load reaction (same for all 3 stringers)
R u1 1.70 [kip] LRFD combo #1: P u  = 1.4P D
R u2 6.35 [kip] LRFD combo #2: P u  = 1.2P D +  1.6P L
R u 6.35 [kip] Ultimate Reaction (max of the two combos)
x 1 3.40 [ft] Interior steel stringer 1 location
x 2 6.80 [ft] Interior steel stringer 2 location
x 3 10.20 [ft] Interior steel stringer 3 location
Interior Stringer, @ 13.6' impacted by vehicle load
R d.steel 1.21 [kip] Dead load reaction
R l.steel 4.82 [kip] Live load reaction
R u1 1.70 [kip] LRFD combo #1: P u  = 1.4P D
R u2 9.17 [kip] LRFD combo #2: P u  = 1.2P D +  1.6P L
R u 9.17 [kip] Ultimate Reaction (max of the two combos)
x 13.60 [ft] Steel stringer location
Exterior Stringer, @ 17' 
R d.steel 0.85 [kip] Dead load reaction
R l.steel 1.53 [kip] Live load reaction
R u1 1.19 [kip] LRFD combo #1: P u  = 1.4P D
R u2 3.47 [kip] LRFD combo #2: P u  = 1.2P D +  1.6P L
R u 3.47 [kip] Ultimate Reaction (max of the two combos)
63
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Troutdale Observation Deck 2021.TROUT.03
D1 Deck Load Calculations 06/11/2021
x 17.00 [ft] Steel stringer location
64
D1 Deck Load Calculations 6/6
Observation Deck 2021.TROUT.03
D2 Reinforced Concrete Girder 06/05/2021
DESIGN INPUTS
Loading
M u-pos 0 [kip ft] Max. positive moment obtained from SAP2000 Model
M u-neg 660 [kip ft] Max. negative moment obtained from SAP2000 Model
V u 77 [kips] Max. shear obtained from SAP2000 Model
Concrete Detail
Concrete Dimensions and Properties
b 22 [in] Girder thickness
h 32.5 [in] Girder depth
L 1 25.5 [ft] Length of backspan
L 2 17 [ft] Length of cantilever
f' c 4 [ksi] Concrete strength
w c 150 [pcf] Weight of concrete
Conc. Cover 3 [in] Concrete cover 
β 1 0.85 [-] ACI Table 22.2.2.4.3
w self 744.79 [plf] Lineal self-weight of the girder
Reinforcement Details 
Steel Properties
f y 60 [ksi] ACI Table 22.2.2.4.3
E s 29000 [ksi] Modulus of Elasticity for Steel
Bottom Steel
Bar No. #10 [-] Bar size
A bar 1.27 [in2] Bar area
d bar 1.27 [in] Bar diameter
# of Bars 2 [-]
Top Steel
Bar No. #10 [-] Bar size
65
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Observation Deck 2021.TROUT.03
D2 Reinforced Concrete Girder 06/05/2021
A bar 1.27 [in2] Bar area
d bar 1.27 [in] Bar diameter
# of Bars 6 [-]
Shear Steel
Bar No. #4 [-] Bar size
A 2bar 0.2 [in ] Bar area
d bar 0.5 [in] Bar diameter
s 10 [in] Stirrup spacing
GIRDER CALCULATIONS
Negative Moment Girder Design
Effective Depth
d 29.5 [in] Effective depth to tension steel centroid
d' 3.00 [in] Effective depth to compression steel centroid
Area of Steel
A' s 2.54 [in2] Area of compression steel
A 2s 7.62 [in ] Area of tension steel
Stress Block Depth
Case 1:  If ε s ' < ε y
c 7.19 [in] Compression zone depth ACI 22.2.2.4.1
ε y 0.00207 [in/in] Longitudinal reinforcement tensile yield strain ACI 21.2.2
ε s ' 0.00175 [in/in] Longitudinal reinforcement compression strain @ Ult. ACI 21.2.2
ε s ' < ε y CASE 1 [-] Check if steel is yielding, if steel has yielded than assumption is 
valid, if steel has not yielded, Case 2 is valid.
Case 2:  If ε s ' > ε y
c 5.58 [in] Compression zone depth ACI 22.2.2.4.1
ε s ' 0.00139 [in/in] Longitudinal reinforcement compression strain @ Ult. ACI 21.2.2
66
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Observation Deck 2021.TROUT.03
D2 Reinforced Concrete Girder 06/05/2021
ε t 0.0129 [in/in] Longitudinal reinforcement tensile strain @ Ult. (in/in)
Moment Capacity
a 6.11 [in] Stress block depth
ε s ' 0.00175 [in/in] Longitudinal reinforcement compression strain @ Ult. ACI 21.2.2
ε t 0.0129 [in/in] Longitudinal reinforcement tensile strain @ Ult. (in/in)
f' s 60.0 [ksi] Longitudinal reinforcement compression stress
A s1 5.08 [in2]
A 2.54 [in2s2 ]
M n1 8060 [kip in] Nominal moment for A s1
M n2 4039 [kip in] Nominal moment for A s2
φ b 0.90 [-] Strength reduction factor for moment ACI 21.2.2
φ b M n 10889 [kip in] Factored nominal moment
Demand to Capacity Ratio
M u-neg 660 [kip ft] Max. negative moment 
φ b M n 907 [kip ft] Factored nominal moment 
M u /φ b M n 0.73 [-] Demand-capacity ratio
M u  < φ b M n OK [-] Factored nominal moment strength check
Positive Moment Girder Design
Effective Depth
d 29.50 [in] Effective depth to tension steel centroid
d' 3.00 [in] Effective depth to compression steel centroid
Area of Steel
A' s 7.62 [in2] Area of compression steel
A 2s 2.54 [in ] Area of tension steel
Stress Block Depth
Case 1:  If ε s ' < ε y
67
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Observation Deck 2021.TROUT.03
D2 Reinforced Concrete Girder 06/05/2021
c 2.40 [in] Compression zone depth ACI 22.2.2.4.1
ε y 0.00207 [in/in] Longitudinal reinforcement tensile yield strain ACI 21.2.2
ε s ' -0.00075 [in/in] Longitudinal reinforcement compression strain @ Ult. ACI 21.2.2
ε s ' < ε y CASE 2 [-] Check if steel is yielding, if steel has yielded than assumption is 
Case 2:  If ε s ' > ε y valid, if steel has not yielded, Case 2 is valid.
c 2.87 [in] Compression zone depth ACI 22.2.2.4.1
ε s ' 0.00014 [in/in] Longitudinal reinforcement compression strain @ Ult. ACI 21.2.2
ε t 0.0278 [in/in] Longitudinal reinforcement tensile strain @ Ult. (in/in)
Moment Capacity
a 2.04 [in] Stress block depth
ε s ' 0.00014 [in/in] Longitudinal reinforcement compression strain @ Ult. ACI 21.2.2
ε t 0.0278 [in/in] Longitudinal reinforcement tensile strain @ Ult. (in/in)
f' s 3.9 [ksi] Longitudinal reinforcement compression stress
A 2s1 2.04 [in ]
A s2 0.50 [in2]
M n1 3484 [kip in] Nominal moment for A s1
M n2 797 [kip in] Nominal moment for A s2
φ b 0.90 [-] Strength reduction factor for moment ACI 21.2.2
φ b M n 3853 [kip in] Factored nominal moment
M u-pos 0 [kip ft] Max. positive moment 
φ b M n 321 [kip ft] Factored nominal moment 
M u /φ b M n 0 [-] Demand-capacity ratio
M u  < φ b M n OK [-] Factored nominal moment strength check
Shear Design
V c 82.1 [kips] Shear strength of concrete
V s 70.8 [kips] Shear strength of steel
V n 152.9 [kips] Nominal shear strength
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Observation Deck 2021.TROUT.03
D2 Reinforced Concrete Girder 06/05/2021
φ v 0.75 [-] Strength reduction factor for shear ACI 21.2.1
φ v V n 114.7 [kips] Factored nominal shear
V u /φ v V n 0.67 [-] Demand-capacity ratio
V u  < φ v V n OK [-] Factored nominal shear strength check
DESIGN CHECKS
Min. Girder Thickness
Backspan
l /16 19.1 [in] Min. thickness for length of backspan
Cantilever
l /8 25.5 [in] Min. thickness for length of cantilever
Design Check
h ≥ h min OK [-] Girder thickness must be greater than min. thickness
Steel Reinforcement Ratio Check
ρ max 0.021 [-] Max. reinforcing ratio
ρ min 0.1 [-] Min. reinforcing ratio
ρ 0.016 [-] Reinforcing ratio
ρ min  < ρ < ρ max OK [-] Reinforcing ratio check
Bar Spacing
b min 15.0 [in] Minimum width for bars need to  be spaced properly ACI 25.2.1
b > b min OK [-] Bar spacing check
69
D2 RC Girder Calculations 5/5
Troutdale Observation Deck 2021.TROUT.03
D3 Steel Stringer Design 05/25/2021
STEEL STRINGER ANALYSIS AND DESIGN
Assumptions
Cross-Sectional Properties and Geometry
Designation W10 X 54
F y 60 [ksi] Grade of steel
A 15.80 [in2] Gross cross sectional area
d 10.10 [in] Actual beam depth
t f 0.62 [in] Flange thickness
b f 10.00 [in] Flange width
t w 0.37 [in] Web thickness
I x 303.00 [in4] Moment of inertia about lateral axis
r x 4.37 [in] Radius of gyration about lateral axis
I y 103.00 [in4] Moment of inertia about vertical axis
r y 2.56 [in] Radius of gyration about vertical axis
Z 3x 60 [in ] Plastic section modulus
A 2web 3.28 [in ] Area of web
J 1.71 [in4] Torsion Constant [note formula used in this sheet is ONLY  for a W beam]
w self 54 [plf] Self weight
Overall Stringer Dimensions
Braces 0 [-] Number of equally spaced braces to prevent flexural torsional buckling
L 18 [ft] Beam length
S 3.4 [ft] Beam OC spacing
Structural Analysis
Loads
w D1 17.70 [psf] Dead load from pultruded fiberglass decking
w D2 6.04 [psf] Dead load from asphalt overlay
w L 100 [psf] Pedestrian area live load via ORSS Table 1607.1 36. Exterior foot bridge
P L 1000 [lbs] Pedestrian concentrated live load via ORSS Table 1607.1 36. Exterior foot bridge
P HL10(Rear) 8 [kips] Vehicular point load
w u 301.66 [plf] Ultimate uniform load
P u1 14.4 [kips] Ultimate point load 1 includes P L  and P H10(Rear)
70
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Troutdale Observation Deck 2021.TROUT.03
D3 Steel Stringer Design 05/25/2021
P u2 12.8 [kips] Ultimate point load 2 includes P H10(Rear)
Reactions and Governing Internal Forces
Assuming stringer is simply supported
R y 25.65 [kips] Vertical Reaction
V u 25.65 [kips] Max Shear
M u 1190.75 [kip in] Max Moment
Structural Design
Servicability
Δ max(D+L) 0.90 [in] Maximum deflection limit per ORSS 1604.3.3
Δ D+L 0.48 [in] Deflection of designated beam under service loads W D  + W L  and P L  + P HL10(Rear)
Δ D+L  < Δ max(D+L)  ? Pass [-] Check serviceability of Dead + Live
Δ max(L) 0.60 [in] Maximum deflection limit per ORSS 1604.3.3
Δ L 0.44 [in] Deflection of designated beam under service loads W L  and P L  + P HL10(Rear)
Δ L  < Δ max(L)  ? Pass [-] Check serviceability of Live
Shear Strength Limit State
φ v 0.7 [-] Reduction factor for shear
V n 118.15 [kips] Nominal shear strength
V u < φ v V n ? Pass [-] Test shear
(D/C) V 0.31 [-] Demand to capacity ratio for shear
71
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Troutdale Observation Deck 2021.TROUT.03
D3 Steel Stringer Design 05/25/2021
Bending Strength Limit State
φ b 0.7 [-] Reduction factor for bending (flexure)
M n 3600 [kip in] Nominal moment strength
M u < φ b M n ? Pass [-] Test bending
(D/C) b 0.47 [-] Demand to capacity ratio for bending
Flexural Buckling Limit State
F e 117.15 [ksi] Eulerian Buckling Stress
L c /r<4.71(E/F )
0.5
y ? Eq E3-2 [-] Determine if buckling is Eulerian
F cr 102.74 [ksi] Critical Buckling Stress
P n 1623.34 [kips] Nominal internal buckling force capacity
Flexural-Torsional Buckling Limit State
r 2 20 51.10 [in ]
H 0.91 [in-1]
F ey 40.20 [ksi] Eulerian Buckling Stress in y direction
F ez 23.73 [ksi] Eulerian Buckling Stress in z direction
F e 21.45 [ksi] Eulerian Buckling Stress
72
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Troutdale Observation Deck 2021.TROUT.03
D3 Steel Stringer Design 05/25/2021
F y /F e < 2.25? Eq E3-3 [-] Determine if buckling is Eulerian
F cr 18.81 [ksi] Critical Buckling Stress
P n 297.27 [kips] Nominal internal buckling force capacity
Buckling Checks
L eff 18 [ft] Effective buckling length with bracing
φ 0.7 [-] Buckling reduction factor
P u 191.60 [kips] Maximum internal force in beam flange calculated from extreme fiber stress
P u < φ*min(P n ) Pass [-] Testing Buckling
DCR 0.92 [-] Demand to capacity ratio for buckling
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Troutdale Observation Deck 2021.TROUT.03
D4 Deck Deflection Calculations 06/11/2021
DESIGN INPUTS
Assumptions
Modulus of Elasticity
Calculated using different fiberglass decking models from the same manufacturer
E 4107143 [psi] E value used for 2" deep T3320
E 631313 [psi] E value used for 1" deep l4010
E 1458333 [psi] E value used for 1-1/2" deep l4015
E 4107143 [psi] E value providing most conservative deflections
Loading
P 10400 [lb] 1/2 AASHTO H-10 Truck + 1.3 Upscale for Impact
Deflection Calculations
1" Deep HI3710
S max 40 in Max allowable span from manufacturer
FS 3 [-] Factor of safety
S 1.1 [ft]
1-1/2" Deep HI3715
S max 55 in Max allowable span from manufacturer
FS 3 [-] Factor of safety
S 1.5 [ft]
2" Deep HI3720
S max 68 in Max allowable span from manufacturer
FS 3 [-] Factor of safety
S 1.9 [ft]
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D4 Deck Deflection Calculations 1/2
Troutdale Observation Deck 2021.TROUT.03
D4 Deck Deflection Calculations 06/11/2021
2-1/2" Deep HI3725
S max 81 in Max allowable span from manufacturer
FS 3 [-] Factor of safety
S 2.2 [ft]
3" Deep HI3730
S max 92 in Max allowable span from manufacturer
FS 3 [-] Factor of safety
S 2.6 [ft]
Use 3" Deep HI3730
Provides the greatest span
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Troutdale Observation Deck 2021.TROUT.03
D5 Compression Pile Design 06/11/2021
COMPRESSION PILE DESIGN
Site Soil Engineering Properties
Layer 1:
Soil Type Fill [-]
z 1 52 to 15 [ft] Layer Depth
γ 1 130.00 [pcf] Soil Unit Weight
Strength Type M-C [-] Strength Type (M-C = Mohr-Coulomb)
c 0.00 [psf] Cohesion
φ 1 40.00 [deg] Friction Angle φ
z w 25.00 [ft] Water Table Depth
Layer 2:
Soil Type Sand + Gravel [-]
z 2 15 to - 5 [ft] Layer Depth
γ 2 125.00 [pcf] Soil Unit Weight
Strength Type M-C [-] Strength Type (M-C = Mohr-Coulomb)
c 0.00 [psf] Cohesion
φ 2 38.00 [deg] Friction Angle φ
z w 25.00 [ft] Water Table Depth
Layer 3:
Only measuring to the bottom of the pile. This layer continues.
Soil Type Silty Clay [-]
z 3 -5 to -8 [ft] Layer Depth
γ 3 120.00 [pcf] Soil Unit Weight
Strength Type M-C [-] Strength Type (M-C = Mohr-Coulomb)
c 0.00 [psf] Cohesion
φ 3 34.00 [deg] Friction Angle φ
z w 25.00 [ft] Water Table Depth
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Troutdale Observation Deck 2021.TROUT.03
D5 Compression Pile Design 06/11/2021
Skin Friction Calculations
u, eff. vert stress, qs, and Qs are calculated based only on the depth of each layer. These values are added 
in a cumulative fashion to calculate Total Qs
Layer 1:
Soil Type Fill [-]
t 1 37 [ft] Layer thickness
u 1 748.80 [psf] Pore Water Pressure, u
γ 1 130.00 [pcf] Soil Unit Weight
σ' v0,1 4061.20 [psf] Effective Vertical Stress for Layer σ'v0 
K 1 0.643 [-] Lateral Earth Pressure Coefficient K = (1.8)*(Ko)
δ 1 26.00 [deg] Friction Angle for Pile Material δ
δ 1 0.454 [rad]
q s1 177125 [psf) Unit Skin Friction, qs = K*σ'v0*tanδ
D 1.00 [ft] Pile diameter
P 3.14 [ft] Pile perimeter
L 37.00 [ft] Pile length
Q s1 20588785 [lb] Total Skin Friction, Qs = qs*π*D*L
Layer 2:
Soil Type Sand + Gravel [-]
t 2 20 [ft] Layer thickness
u 2 1248.00 [psf] Pore Water Pressure, u
γ 2 125.00 [pcf] Soil Unit Weight
σ' v0,2 1252.00 [psf] Effective Vertical Stress for Layer σ'v0 
K 2 0.692 [-] Lateral Earth Pressure Coefficient K = (1.8)*(Ko)
δ 2 24.70 [deg] Friction Angle for Pile Material δ
δ 2 0.431 [rad]
q s2 2071 [psf) Unit Skin Friction, qs = K*σ'v0*tanδ
D 1.00 [ft] Pile diameter
P 3.14 [ft] Pile perimeter
L 20.00 [ft] Pile length
Q s2 130122 [lb] Total Skin Friction, Qs = qs*π*D*L
Layer 3:
Soil Type Silty Clay [-]
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D5 Pile Calculations 2/7
Troutdale Observation Deck 2021.TROUT.03
D5 Compression Pile Design 06/11/2021
t 3 3 [ft] Layer thickness
u 3 187.20 [psf] Pore Water Pressure, u
γ 3 120.00 [pcf] Soil Unit Weight
σ' v0,3 5212.80 [psf] Effective Vertical Stress for Layer σ'v0 
K 2 0.793 [-] Lateral Earth Pressure Coefficient K = (1.8)*(Ko)
δ 3 22.10 [deg] Friction Angle for Pile Material δ
δ 3 0.052 [rad]
q s3 73289 [psf) Unit Skin Friction, qs = K*σ'v0*tanδ
D 1.00 [ft] Pile diameter
P 3.14 [ft] Pile perimeter
L 3.00 [ft] Pile length
Q s3 53690 [lb Total Skin Friction, Qs = qs*π*D*L
Q s 20772597 [lb] Total Skin Friction Qs (lb)
End Bearing Calculations
Soil Type Silty Clay [-] Total End Bearing (lb)
φ' 34 [deg] Friction Angle φ'
φ' 0.593 [rad] Friction Angle φ'
N q 29.40 [-]
 q p 19.83 [psf] Unit End Bearing q p  = σ' v0 *N q *50≤(tanφ')*N q
A 2base 0.785 [ft ] Area of the pile base
Q p 15.60 [lb] Total End Bearing (lb) Q p  = q p *A base
Bearing Capacities: Q ultimate, Q allowable, # of Piles 
Q ult 2072613 [lb] Qult = Qp + Qs
 FS 3 [-]
Q all 6924204 [lb] Qall = Qult/FS
Factored load 30181140 [lb]
# of piles 4.00 [-]
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Troutdale Observation Deck 2021.TROUT.03
D5 Tension Pile Design 06/11/2021
TENSION PILE DESIGN
Site Soil Engineering Properties
Layer 1:
Soil Type Fill [-]
z 1 52 to 15 [ft] Layer Depth
γ 1 130.00 [pcf] Soil Unit Weight
Strength Type M-C [-] Strength Type (M-C = Mohr-Coulomb)
c 0.00 [psf] Cohesion
φ 1 40.00 [deg] Friction Angle φ
z w 25.00 [ft] Water Table Depth
Layer 2:
Soil Type Sand + Gravel [-]
z 2 15 to - 5 [ft] Layer Depth
γ 2 125.00 [pcf] Soil Unit Weight
Strength Type M-C [-] Strength Type (M-C = Mohr-Coulomb)
c 0.00 [psf] Cohesion
φ 2 38.00 [deg] Friction Angle φ
z w 25.00 [ft] Water Table Depth
Layer 3:
Only measuring to the bottom of the pile. This layer continues.
Soil Type Silty Clay [-]
z 3 -5 to -8 [ft] Layer Depth
γ 3 120.00 [pcf] Soil Unit Weight
Strength Type M-C [-] Strength Type (M-C = Mohr-Coulomb)
c 0.00 [psf] Cohesion
φ 3 34.00 [deg] Friction Angle φ
z w 25.00 [ft] Water Table Depth
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D5 Pile Calculations 1/3
Troutdale Observation Deck 2021.TROUT.03
D5 Tension Pile Design 06/11/2021
Skin Friction Calculations
u, eff. vert stress, qs, and Qs are calculated based only on the depth of each layer. These values are added 
in a cumulative fashion to calculate Total Qs
Layer 1:
Soil Type Fill [-]
t 1 37 [ft] Layer thickness
u 1 748.80 [psf] Pore Water Pressure, u
γ 1 130.00 [pcf] Soil Unit Weight
σ' v0,1 4061.20 [psf] Effective Vertical Stress for Layer σ'v0 
K 1 0.643 [-] Lateral Earth Pressure Coefficient K = (1.8)*(Ko)
δ 1 26.00 [deg] Friction Angle for Pile Material δ
δ 1 0.454 [rad]
q s1 177125 [psf) Unit Skin Friction, qs = K*σ'v0*tanδ
D 1.00 [ft] Pile diameter
P 3.14 [ft] Pile perimeter
L 37.00 [ft] Pile length
Q s1 8519017 [lb] Total Skin Friction, Qs = qs*π*D*L
Layer 2:
Soil Type Sand + Gravel [-]
t 2 20 [ft] Layer thickness
u 2 1248.00 [psf] Pore Water Pressure, u
γ 2 125.00 [pcf] Soil Unit Weight
σ' v0,2 1252.00 [psf] Effective Vertical Stress for Layer σ'v0 
K 2 0.692 [-] Lateral Earth Pressure Coefficient K = (1.8)*(Ko)
δ 2 24.70 [deg] Friction Angle for Pile Material δ
δ 2 0.431 [rad]
q s2 11517 [psf) Unit Skin Friction, qs = K*σ'v0*tanδ
D 1.00 [ft] Pile diameter
P 3.14 [ft] Pile perimeter
L 20.00 [ft] Pile length
Q s2 723642 [lb] Total Skin Friction, Qs = qs*π*D*L
Layer 3:
Soil Type Silty Clay [-]
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D5 Pile Calculations 2/3
Troutdale Observation Deck 2021.TROUT.03
D5 Tension Pile Design 06/11/2021
t 3 3 [ft] Layer thickness
u 3 187.20 [psf] Pore Water Pressure, u
γ 3 120.00 [pcf] Soil Unit Weight
σ' v0,3 5212.80 [psf] Effective Vertical Stress for Layer σ'v0 
K 2 0.793 [-] Lateral Earth Pressure Coefficient K = (1.8)*(Ko)
δ 3 22.10 [deg] Friction Angle for Pile Material δ
δ 3 0.385 [rad]
q s3 6350 [psf) Unit Skin Friction, qs = K*σ'v0*tanδ
D 1.00 [ft] Pile diameter
P 3.14 [ft] Pile perimeter
L 3.00 [ft] Pile length
Q s3 59848 [lb Total Skin Friction, Qs = qs*π*D*L
Q s 20772597 [lb] Total Skin Friction Qs (lb)
End Bearing Calculations
End bearing not considered for tension piles
 Q p 0.00 [lb] Total End Bearing (lb)
Bearing Capacities: Q ultimate, Q allowable, # of Piles 
Q ult 9302507 [lb] Q ult  = Q p  + Q s
 FS 3 [-] Factor of Safety
Q all 3100836 [lb] Q all  = Q ult /FS
Factored load 111826000 [lb]
# of piles 4.00 [-]
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A PPENDIX  E  
SI TE P H OTOS  
  
 8 2
Sandy River Observation Deck
Group: 2021.TROUT.03
Project Purpose 
and Background Aerial View and Drone Pictures
● Location: ● Objectives: ● Accurate aerials for conceptual design and drafting
○ Sandy Riverfront Park in Troutdale, OR ○ Design a cantilevered observation deck with a scenic view of the ● 2D orthomosaic imaging for large, high-resolution photos
○ South of I-84, north of downtown Troutdale, Sandy River ● Required FAA authorization to fly in local airport airspace
east of the Columbia Gorge Outlets ○ The deck must blend with the flow of the nearby planned trail
○ Provide a space for local trail users to slow down and enjoy the 
scenic riverfront
○ Orient the deck to face the railroad bridge across a scenic bluff 
Alternatives 
to the southeast Analysis
TABLE 1: Pugh Matrix used in the Alternative Analysis 
CRITERIA
ALTERNATIVE TITLE & Resiliency 
DESCRIPTION Cost Constructability
Environmental User 
Impact Experience and Maintenance PermittingStrength
1) Large Deck, Cable-Stayed 1 1 3 5 5 4 3
Figure 3: View of the site facing southeast towards the 
2) Large Deck, Cantilevered 2 2 3 4 2 1 3 scenic bluff, retrieved via drone
Figure 1: Project location
3) Small Cantilever Deck 4 3 3 2 3 2 4
4) Small Deck, Wide and  
Existing Site Conditions Shallow
3 4 4 2 4 3 4 Consideration for 
5) No-Build 5 5 5 1 5 5 5 Professional Practice
CRITERIA WEIGHTS 9 6 5 7 8 9 8
● Site use and layout has changed several times in the last 100 years
● This capstone team is split up into different departments:  
○ In that time, the river course has remained unchanged Alternative ○ Geotechnical Design
● Soil is mostly fill, loose and gravelly Design ○ Structural Design
● Moderately vegetated with grass, blackberry, and several species of trees Solution
○ CAD Team
● Stormwater drainage pipe with an easement south of the site
○ General Civil
TABLE 2: Alternative Scoring ● Key Criteria: ● Each team is managed by an APM 
ALTERNATIVE TITLE & TOTAL Order by ○ Maintenance, Cost and Strength
DESCRIPTION SCORE high-score to low ○ Higher total scores indicate the alternative is 
1) Large Deck, Cable-
Stayed 165 2nd preferable
2) Large Deck, 122 4th ● Design must optimize user experience and comply with Cantilevered
3) Small Cantilever regulations
Deck 157 3rd
4) Small Deck, Wide ● Provide aesthetic views to the Sandy River
and Shallow 176 1st
5) No-Build 232 N/A
Figure 2: Aerial view of the project location, Figure 4: Organizational Chart outlining the 
retrieved via drone structure of the team
Stakeholders
● City of Troutdale Urban Renewal Agency
● Eastwinds Development, LLC
● Oregon Metro
● Sandy River Basin Watershed Council
● Troutdale Parks and Facilities
● End user: the general public
Prepared by:
Casey Keller Drew Hill
Anh Le Jillian Pfeifer
Ezra Albright Brooke Annotti
Ian Buslach Elizabeth Gartner
Elijah Kling Justin Potts
Leen Qwider Jordan Real
Marie Roza Matthew Stewart
Tran Tran Arthur Yurov
Savko Zagaryuk
Figure 5: Alternative 4 Small Deck, Wide and Shallow
83
Sandy River Observation Deck
Group: 2021.TROUT.03
Proposed 
Proposed Design Design Drafts
Description Design 
*Note: Deck dimensions have changed as of the client meeting Assumptions, 
*Note: Deck dimensions have changed as of the client meeting on Friday (04/23). Drafted designs featured in this poster Codes, and 
on Friday (04/23). The dimensions below are the updated are based on the previous proposed width of 24’ Permits
dimensions.
● Dimensions: ● Key Design Assumptions:
○ Cantilever length = 15’ ○ Deck is effectively rectangular for structural 
○ Back Span length = 22.5’ calculations
○ Deck width = 12’ ○ Modeling the deck this way provides more 
conservative load estimates
● Design Elements:
○ Rounded deck for natural feel ● Codes:
○ Deck surrounded by plaza ○ Oregon Structural Specialty Code (ORSS)
○ Setback from FEMA 100-year event line ○ PROWAG ADA-Compliance
○ At Finished Grade of nearby trail
● Permits:
○ Permit for Floodplain Development – FEMA
○ Flood Hazard Permit – City of Troutdale
○ Basic Public Works Permit – City of Troutdale
Decking and 
Structural Framing
Figure 5: Southeast view of the deck design, drafted using SketchUp
● Decking Material: Pultruded Fiberglass 
Pros:
○ Lightweight and durable
○ Low maintenance
Cons:
● ○DeckMinogd Seurpatpeo urtp: frontS cteoestl Girders 
Pros:
○ High strength-to-weight ratio
○ Low construction costs Next Steps
Cons:
● Refine Deep Foundation (Pile) Design
● G○irdeInri tSiualp cpoosrtt :is  higheRre (icnofmorpcaerde Cdo tnoc croentec rBeetea mansd timber)
Figure 6: Legend for the drafted plan view (see Figure 7) ● Refine Structural Framing Design
Pros: ● Cost Estimating
○ Resistant to weathering ● Final Permit Checks
○ Low maintenance Figure 7: Plan view of the proposed design, drafted using Autodesk Civil 3D ● Polished CAD and SketchUp views
○ Durable
Cons:
○ Weaker in tension
Structure 
Foundation
● Deep piles supporting the above reinforced concrete beams Prepared by:
○ Site soil is relatively unstable fill Casey Keller Drew Hill
○ Piles provide friction from soil to stabilize structure Anh Le Jillian Pfeifer
Ezra Albright Brooke Annotti
Ian Buslach Elizabeth Gartner
Elijah Kling Justin Potts
Leen Qwider Jordan Real
Marie Roza Matthew Stewart
Figure 8: East-facing view of the deck design, drafted using SketchUp Tran Tran Arthur Yurov
Savko Zagaryuk
84
Appendix F
Final Presentation
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SCI Directors and Staff
Marc Schlossberg SCI Co-Director, and Professor of Planning,
 Public Policy and Management, 
 University of Oregon
Nico Larco SCI Co-Director, and Professor of Architecture,
 University of Oregon
Megan Banks SCYP Director, University of Oregon
Nat Kataoka Report Coordinator
Danielle Lewis Graphic Designer