Final report design of a pedestrian bridge - fall 2009

The University of Toledo Department of Civil Engineering

Senior Design Project Fall 2009

Final Report for Design of a Pedestrian Bridge: Group 4

Submitted to: Dr. Jiwan Gupta, Ph.D., P.E. Submitted By: Ryan Askins Chris Beckert Josh Dobrzeniecki Kyle Kreft Nick Zenk Advisors: Dr. Jiwan Gupta, Ph.D., P.E.

Dr. Douglas Nims, Ph.D., P.E. Dr. Andrew Heydinger, Ph.D., P.E.

Group 4 | Design of a Pedestrian Bridge 1

Disclaimer

This report is student work. The contents of this report reflect the views of the students who

are responsible for the facts and the accuracy of the data presented herein. The contents do

not necessarily reflect the views of the University of Toledo. The recommendations,

drawings and specifications in this report should not be used without consulting a

professional engineer.


Table of Contents

Disclaimer……………………………………………………...……………………...............1

Table of Contents………………………………………………………………………........2-3

Acknowledgements...………………………………………………………………………….4

1.0 Problem Statement………………………...…………………………………………………..5

2.0 Purpose and Objective…………………………………………………………...…………….5

3.0 Constraints…………………………………………………………………….……………….6

3.1 High Tension Power Transmission Lines……………………………………..……6-7

3.2 Railroad Tracks...……………………………………………………………..…….7-8

3.3 Soil Conditions…………………………………………………………………….….8

4.0 Site Visits…………………………………………………...………………………..……..…9

4.1 Vehicular Traffic Data……………………………………………………….……9-11

4.2 Pedestrian Traffic Data...…………………………………………………………….11

4.3 Pictures………………...…………………………………...…………….………11-13

4.4 Site Survey……………………………….…………………………………….…….13

5.0 Recommended Design Options………………………………………………..................13-15

6.0 Proposed Bridge Design………………………………………………………...……………15

6.1 Solar Panel System Design……………………………………………..………..15-16


6.2 Through Truss Bridge Design………………...…………………………...……..16-20

6.3 Welded Connections……………….……….. ………………..…………………..…20

6.4 Bridge Abutment Design………………...………………………………...……..21-22

6.5 Ramp Design…………………..…………………………………………………22-23

6.5.1 Ramp Materials and Construction………………………….………......23-25

7.0 Alternative Bridge Design………………..…………………………………………………..26

7.1 Geothermal Heating………………………………………………..…………….26-27

8.0 Estimated Cost of Proposed Design………………………………………………………….28

9.0 Estimated Cost of Alternative Design………………………………………………………..29

10.0 References……………………………………………………………..………….………30-31

Appendix A - Site Conditions ………………………………………...………………...…...32

Appendix B – Through Truss Bridge Design …..……..……….………………………...….46

Appendix C – Abutment Design……………..……………………………………………....98

Appendix D – Ramp Design……………………………………………………..…………104

Appendix E – Design Team Resumes………………………………………………………112

Appendix F – Detailed Drawings…………..…………………………………………….…118


Acknowledgements:

The design team would like to thank the professionals who provided their assistance in this project.

Their efforts made much of the design possible, and the project could not have been completed

without their help. The design team greatly appreciates the guidance and support that the following

individuals provided:

Dr. Jiwan Gupta, Ph.D., P.E.- The University of Toledo, Civil Engineering Department

Dr. Douglas Nims, Ph.D., P.E.- The University of Toledo, Civil Engineering Department

Dr. Andrew Heydinger, Ph.D., P.E.- The University of Toledo, Civil Engineering

Department

Dr. Nagi Naganathan, Ph.D., P.E. – Dean of The University of Toledo College of

Engineering

Charles Lehnert – Vice President Facilities and Construction, The University of Toledo

Xiaozhong Zhang- The University of Toledo, Facilities and Construction

Tom Stopak- First Energy

Roger Streiffert- Toledo Metropolitan Area Council of Governments (TMACOG)

Sharon Parker- CSX Transportation Inc.

Frank Mortali – City of Toledo, Department of Public Utilities Division of Engineering

Services

Jim O’Connell – Tech Dynamics, Inc.

Walter Erickson – Interstate Commercial Glass & Door

Mark Tuttle – Advanced Distributed Generation, LLC

Louis Haefner – Schindler Elevator Corporation

Greg Veltema – Kerkstra Precast, Inc.

Chad Henkle – Toledo Caisson Corporation

Peter Hetzel - EcoHill LLC

Steve Kerr – Solite, LLC


3.0 - Constraints:

The University of Toledo property adjacent to the Douglas Road and Oakwood Avenue intersection

specified above, where the proposed pedestrian bridge is to be constructed is zoned institutional.

Due to the fact that the bridge will cross City of Toledo property (Douglas Road) it will be necessary

for the University to coordinate with the City Zoning and Planning Commission in order to obtain

permission as well as any permits that may be required.

3.1 - High Tension Power Transmission Lines

During the design team’s initial site assessment, many potential issues were discovered. The first and

most challenging issue in designing and constructing a pedestrian bridge at the proposed location is

the high tension power transmission lines that obstruct the overhead area along Douglas Road. Due

to the fact that these particular power transmission lines are 138 kV, there are National Electrical

Safety Codes (NESC) that must be adhered to during the design and construction process in order to

ensure pedestrian safety.

Below is a drawing of the 138 kV power transmission lines (Figure 2) along Douglas Road at the

Oakwood Avenue intersection. Tower #149 is located just north of Oakwood Avenue. This is the

particular tower in which all NESC clearance requirements need to be accounted for in the proposed

bridge design. The figure shows the sag curve for the bottom wires between Towers #149 and #150.

Tower #150 is located at the northwest corner of Door Street and Douglas Road. The figure also

shows the height to the bottom wires at each tower, which is 63’-0” at Tower #149 and 75 feet at

Tower #150. The clearance above ground at the low point of sag between Towers #149 and #150 is

31 feet (please see Appendix A: page 41 for a larger drawing).

Figure 2: Rough Sketch of Power Transmission Lines. (Source: FirstEnergy)


The first clearance requirement to be considered is a mandatory 25’-0” horizontal clearance around

the base of the transmission towers in order to allow for maintenance vehicle access. NESC requires

a vertical clearance of 21’-0” between 138 kV lines and land accessible to vehicles, or 17’-0”

between 138 kV lines and land accessible to only pedestrians. However, in the case of an enclosed

structure that does not have access to the roof through a doorway, stairway, or permanent mounted

ladder, the roof is considered inaccessible to pedestrians and the NESC’s minimum vertical clearance

over the roof is 15’-0”. If the previously described clearance requirements cannot be met, an

additional transmission tower can be installed at the sag point of the existing lines to raise them for

approximately $75,000.

3.2 - Railroad Tracks

In addition to the clearances required for the power transmission lines, clearances for vehicle and

railroad traffic must also be taken into account during the design process. Railroad traffic clearances

come into consideration due to the existing railroad tracks that cross Oakwood Avenue and continue

to run parallel along the east side of Douglas Road. In order to provide for the safe passage of

railroad traffic underneath an overhead structure, the structure must be a minimum of 23’-0” above

the center line of the track itself (Figure 3).

Figure 3: Clearances Required for Overhead Structures.

(Source: http://www.csx.com/share/media/media/docs/CSX_Public_Project_Manual-REF21857-REF22268.pdf)

CSX Transportation, Inc. and the Toledo Metropolitan Area Council of Governments (TMACOG)

have proposed and are currently working towards abandoning the portion of the Toledo Backside

Railroad tracks running through the proposed site. If the proposed abandonment goes through as

planned the overhead clearances for railway traffic would not necessarily have to be taken into

account for design purposes. The proposed abandonment stretches from Railroad Milepost CTT 5

(near the Jackman and Laskey intersection in Toledo, Ohio) to Railroad Milepost CTT 9.15 (near the

Douglas and Door intersection in Toledo, Ohio). This 4.15 mile stretch of track is currently inactive

with parts of it already removed and is part of TMACOG’s long range plan to potentially become a


future pedestrian/bike path. Please see Figure 4 below in which the red line indicates the portion of

the Toledo Backside Railroad track that is being proposed to be abandoned between the Temperance

and Vulcan junctions.

Figure 4: Proposed Abandonment of Toledo Backside. (Source: CSX/TMACOG)

3.3 - Soil Conditions

Soil conditions have a major impact on the design and construction process. A previous soil boring

report was obtained from TTL Associates, Inc for the new Nitschke Technology and

Commercialization Complex, which is located just southeast of the proposed location for the new

pedestrian bridge. The information obtained from the boring report allowed for the soil conditions to

be studied from the ground surface to a depth of 80’-0”. Descriptions of each soil layer, each layer’s

unconfined compressive strength as well as the dry unit weight were obtained from the soils report.

From the report it was easy to determine that the site soil conditions were very poor, with moist loose

silty sand and wet soft clay from the surface to a depth of around 59’-0” where the soil becomes very

stiff. Please see Appendix A: page 42-45 for a copy of the soil boring report.


4.0 - Site Visits:

The proposed site is located at the intersection of Douglas Road and Oakwood Avenue in Toledo,

Ohio with an approximate latitude and longitude coordinates of 41˚39’ 20.92” N, 83˚ 36’ 31.82” W.

Figure 5: Proposed Site Location

The pedestrian bridge is to cross the northern leg of the Douglas Road and Oakwood Avenue

intersection. The bridge will begin next to commuter parking lot #19 on the east side of the

intersection, span Douglas Road, and end next to the University Computer Center parking lot on the

west end of the intersection (Figure 5).

Motor vehicles and pedestrians have always been known to present conflicts with one another.

These points of conflict can be very obvious at the intersection of Douglas Road and Oakwood

Avenue due to the high flow of pedestrians traveling between The University of Toledo Main

Campus and the Engineering Campus, in conjunction with the high levels of vehicular traffic around

the University. During multiple site visits to the proposed pedestrian bridge location, pedestrian and

vehicular traffic data was observed and recorded. This was done in an effort to better understand and

verify the need to provide pedestrians with a safer means to cross Douglas Road.

4.1 - Vehicular Traffic Data

The posted speed limit on Douglas Road is 40 miles per hour; however a field investigation revealed

that many people drive between 50 and 55 miles per hour (mph) along Douglas Road, which

compromises the safety of pedestrians using the current crosswalk. According to TMACOG the


Average Daily Traffic (ADT) on Douglas Road is 23,700 vehicles per day (this data it the most

recent available and is from 2002). Please see Figure 6 below for a traffic map of Toledo from 2005.

Figure 6: Traffic Flowmap for Toledo.

(Source: http://www.tmacog.org/Transportation/Traffic%20Flow/Flow%20map%2005.pdf)

With an ADT of 23,700 the peak hourly flow would be approximately 2,133 vehicles. This value

was calculated assuming that 9% of the ADT passes though the area during the peak hour. A one

hour traffic study was completed on October 15, 2009, in which 1,381 vehicles were observed

traveling through the intersection between 2:00 and 3:00 PM. This traffic count included all vehicles

traveling:

North and south on Douglas Road

From the Engineering Campus straight across Douglas Road to Main Campus and vice versa

From the Engineering Campus turning left or right onto Douglas Road from Oakwood

Avenue


From Main Campus turning left or right onto Douglas Road

North on Douglas Road turning right towards the Engineering Campus or left into Main

Campus

South on Douglas turning right into Main Campus or left into the Engineering Campus

4.2 - Pedestrian Traffic Data

Multiple field studies were conducted on different dates and at different times to obtain an accurate

understanding of the number of pedestrian crossing Douglas Road at the Oakwood Avenue

intersection. Below is the data collected:

325 per hour (observed between 12 and 1 PM on 9/3/09)

290 per hour (observed between 10 and 11 AM on 9/14/09)

56 per hour (observed between 2 and 3 PM on 10/15/09)

The times that the traffic and pedestrian counts were made greatly impacted the outcome. It can be

seen the greatest pedestrian flow across Douglas Road occurred between the hours of 12:00 and 1:00

PM. This is mainly due to the class schedule of The University of Toledo students. Most classes are

scheduled around noon rather than earlier in the morning or later in afternoon. This is also around the

same time when most people with full-time jobs go to lunch. The large amount of vehicular traffic

from the University in addition to the speed at which vehicles travel down Douglas Road presents a

major safety hazard for pedestrians in the area. This situation is exacerbated by students who may

not be paying attention while crossing the road and emphasizes the need for a pedestrian bridge. The

same could be concluded for vehicular traffic in the area.

4.3 - Pictures

Figure 7: Site Image 1 (looking west) Figure 8: Site Image 2 (looking east)


The images on the previous page are pictures of the proposed site from different areas and directions.

Figure 7 looks west towards The University of Toledo Main Campus on the north side of Oakwood

Avenue across Douglas Road. Figure 8 looks east towards the Engineering Campus on the north side

of Oakwood Avenue across Douglas Road. Transmission Tower #149 and the accompanying power

lines can be seen on the left hand side of Figure 8.

Figure 9: Site Image 3 (looking south) Figure 10: Site Image 4 (looking northeast)

Figure 9 is looking south and is parallel to the east side of Douglas Road. This picture shows power

transmission tower #149 to the right and the Toledo Backside railroad tracks running down the center

of the image. Figure 10 is looking northeast on the north side of Oakwood Avenue in front of the

Engineering Campus. Power transmission tower #149 can also be seen in the center of the image

with the railroad tracks located in front of it.

Figure 11: Site Image 5 (looking west) Figure 12: Site Image 6 (looking north)

Figures 11 and 12 show commuter parking lot #19, which is located on the corner of Oakwood

Avenue and Westwood directly in front of the North Engineering Building on the Engineering

Campus. Figure 11 is looking west towards Main Campus between Oakwood Avenue on the left and

commuter parking lot #19 on the right. Figure 12 is looking north towards Bancroft between


commuter parking lot #19 on the left and Westwood on the right.

4.4 - Site Survey

A site survey was performed to check the elevations at different areas of the project site. This was

completed to ensure that the bridge is designed and constructed within the given clearance

requirements. It was determined that the intersection of Douglas Road and Oakwood Avenue is

approximately 3 feet higher in elevation than the intersection of Oakwood Avenue and Westwood

Avenue.

5.0 - Recommended Design Options:

After conducting multiple field visits to the proposed bridge location and obtaining all of the

necessary background information for the site as well as the necessary clearance requirements for all

of the design obstacles, the design team has come up with two potential design solutions. Each of the

potential design solutions was designed in an effort to safely transport pedestrians across Douglas

Road without causing an unnecessary delay to traffic as well as to connect The University of Toledo

Main Campus with the Engineering Campus.

The first design option that was explored accounted for the CSX Transportation, Inc. Toledo

Backside Railroad lines that are running parallel to Douglas Road to remain open and in-service.

Therefore, a vertical clearance of 23’-0” was maintained between the top of the Railroad lines and

the bottom of the bridge structure. Due to the 23’-0” vertical clearance that needed to be maintained,

in addition to the limited space that is available for the bridge design, fully enclosed and temperature

controlled towers with a floor height of 25’-0” above ground level equipped with elevators, per

section 4.10 of the ADA Accessibility Guidelines for Buildings and Facilities (ADAAG), need to be

constructed on either side of Douglas Road to give pedestrians access to the steel through truss

bridge spanning Douglas Road and the Railroad tracks. Listed below are some pros and cons of

having the rail line remaining active:

Railroad Lines Remain Open and In-Service – Pros

- Pedestrian safety

- Aesthetically pleasing

- Utilize existing configuration of Parking Lot 19

- Toledo Backside Railroad tracks remain open and in-service

Railroad Lines Remain Open and In-Service – Cons

- Expensive to construct

- Expensive to maintain and operate

- Elevators to meet ADA requirements

- Elevator maintenance


- Inaccessible to bicycles

- Fully enclosed and heated

- Haven for homeless individuals in the area as well as other unwanted activity creating a

safety issue for students and pedestrians

- Undesirable means to cross the Douglas Road (pedestrians would rather use the existing

cross walk as opposed to climbing up and down 25’-0” of stairs)

The second design option that was explored assumed that CSX Transportation, Inc. and TMACOG

are going to implement their plan of abandoning the Toledo Backside Railroad lines running parallel

to Douglas Road. The abandonment of the Railroad lines offers many advantages and widens the

range of design alternatives. Most notably, assuming that the Railroad lines are going to be

abandoned enabled the vertical clearance to the bottom of the structure to be lowered. The standard

vertical clearance between the bottom of the structure and Douglas Road that needed to be met was

now only 14’-6”. However this vertical clearance was increased to 15’-6” to account for the

additional 1’-0” of vertical clearance required by AASHTO for pedestrian bridges in order to reduce

the risk of vehicle collisions with the superstructure of the bridge. The lowering of the vertical

clearance enabled the towers and elevators on either side of Douglas Road to be eliminated, allowing

for ADA and bicycle accessible approach ramps to be constructed in their place to give pedestrians

access to the steel through truss bridge spanning Douglas Road. Listed below are some pros and

cons of having the rail line abandoned:

Abandon Railroad Lines - Pros

- Pedestrian safety

- Aesthetically pleasing

- Cost efficient

- Inexpensive to maintain and operate

- Accessible to bicycles

- Future bike path connection with the University/Parks Trail and a possible connection to a

future Westside corridor bike facility

- ADA accessible ramps (elevators are not required)

- User friendly

Abandon Railroad Lines - Cons

- Permanently Eliminating the Railroad Line

- Reconfiguration of Parking Lot 19 which eliminates 20 parking spaces

Due to the fact that the bridge is to connect the University of Toledo Main Campus with the

Engineering Campus, design considerations were taken into account in an effort to tie in the different

architectural design themes of each respective campus. Keeping this in mind, a limestone veneer is

proposed for either the towers or the approach ramps in the first and second design options

respectively, in order to tie in and incorporate the architectural design on Main Campus. Finally, a


structural steel through truss bridge design with enclosed glass sides is proposed in both design

options to tie in and incorporate the architectural design on the Engineering Campus.

6.0 - Proposed Bridge Design

After talking to members from The University of Toledo Facility and Construction Department, The

College of Engineering, TMACOG and careful consideration of the pros and cons for each of the

potential design options, the design team is proposing to accept the second design option. This

particular design option assumes that CSX Transportation, Inc. and TMACOG are going to abandon

the Toledo Backside Railroad lines along Douglas Road. The proposed design offers many

advantages over the alternative, which will in turn drastically add to the value of the structure for its

pedestrian users, The University of Toledo as well as The City of Toledo as a whole.

During the selection of the proposed design, cost considerations in addition to the overall usability of

the structure for The University of Toledo students as well as for other pedestrians were used as

determining factors. Being able to design under the assumption that the Toledo Backside Railroad

lines are going to be abandoned enabled the design team to not only significantly reduce the

construction and maintenance costs of the structure but also (and arguably more importantly)

significantly add to the overall usability of the structure for The University of Toledo students as well

as other pedestrians in the area.

6.1 - Solar Panel System Design

In an effort to create a sustainable structure and to compliment the green building initiatives of The

University of Toledo, the structural steel through truss portion of the bridge has been designed to

have solar panels mounted along the south side of the roof. The optimal angle to mount solar panels

is equal to the angle of latitude at the proposed location, which is 41.656735o for our location, please

see Figure 13 below.

Figure 13: Site Coordinates http://solartradingpost.com/solar-angle-calculators.html

http://solartradingpost.com/solar-angle-calculators.html


This mounting angle can however be within 15o either direction of the optimal angle without losing

much power or efficiency from the solar panels, with lower angles being better for summer months

and higher angles being better for winter months (http://solartradingpost.com/solar-angle-calculators.html).

With this in mind and the limited overhead space that is available due to the clearance requirements

for the 138 kV power transmission lines, the design team came up with gable roof design that is

20’-0” wide with a peak height of 6’-0”. The proposed roof design gives a mounting angle for the

solar panels of 30.96o, which is well within the 15o allowable range without losing much power or

efficiency from the solar panels (please see Appendix B: page 50 for solar panel mounting angle

calculations). The solar system will consist of 92 General Electric GEPVp-200 Photovoltaic

Modules, each with a peak power output of 200 watts, which will be tied into the main electric grid

(please see Appendix: B pages 48-49 for solar panel cut sheet). The credit that University will

receive for the electrical power generated by the solar system will work towards powering the

lighting for the bridge in addition to other electrical power used by the University.

Using a conservative year round average estimate of 4 hours of peak sunlight per day for solar power

generating purposes, the proposed system will generate approximately 26,864 kilowatt hours of

electricity per year. Furthermore, assuming a conservative price of $0.08 per kilowatt hour, the

system will save the University approximately $2,150 per year in energy costs. (See Appendix B:

page 51 for solar power generation and cost savings calculations). The University should also be

able to get up to 65% of the initial cost of the solar system back through local and federal

government incentives and tax credits.

6.2 - Through Truss Bridge Design

The structural steel through truss portion of the pedestrian bridge which spans Douglas Road was

designed in version 12 of SAP2000 according to AASHTO LRFD Bridge Design Specifications, as

well as the Modifications for AASHTO LRFD Bridge Design Specifications to Incorporate or

Update the Guide Specifications for Design of Pedestrian Bridges. The dimensions and loadings that

were designed for in SAP2000 are listed below:

Design Dimensions

- Clear Span = 150’-0” (fifteen 10’-0” bays)

- Truss Depth = 11’-2”

- Clear Width = 16’-0”

- Clear Height = 10’-0”

- Gable Roof:

o Width = 20’-0”

o Height = 6’-0”

o Pitch = 30.96o

- One-Way Concrete Slab = 6”


Design Loadings

- Dead Load* = The self weight of the steel members is accounted for in SAP2000

- Pedestrian Live Load = 90 psf (Modifications for AASHTO….. Design of Pedestrians

Bridges Section 3.1)

- Slab Dead Load = 75 psf (please see Appendix B: pages 52-53 for Calculations)

- Glass Dead Load = 10 psf (Glass Association of North America, Appendix B: page 47)

- Roof Dead Load = 20 psf (Estimated)

- Snow Load = 20 psf (Estimated)

- Solar Panel Dead Load = 3 psf (See Appendix B: pages 48-50 for calculations, and material

cut sheet)

- Wind Load = 16.1067 psf (AASHTO 3.8.1.2.1-1, See Appendix B: page 54 for Calculations)

* The dead load (self weight) of the steel is multiplied by a factor of 1.05 to account for any

mechanical and electrical system dead loading

The design loadings listed above were entered into SAP2000 as joint loads based upon the

appropriate tributary areas (please see Appendix B: page 55-59 for all tributary area loading

calculations).

According to Section 3.2 of the Modifications for AASHTO LRFD Bridge Design Specifications to

Incorporate or Update the Guide Specifications for Design of Pedestrian Bridges if the clear width of

the bridge is greater than 10’-0” a H10 (20 Kip) design vehicle must be accounted for. Section 3.2

also states that the vehicle loading is not to be placed in combination with the pedestrian loading, and

that the dynamic load allowance does not need to be considered for the vehicle loading. Due to the

fact that the pedestrian loading is so large and the span of the bridge is so long, the pedestrian loading

will control and the vehicle loading was not required to be input into SAP2000 (please see Appendix

B: page 60 for vehicle calculations).

The load combinations were obtained from AASHTO Table 3.4.1-1. After consulting with Dr.

Douglas Nims from the Civil Engineering Department at The University of Toledo, the design team

concluded that it is necessary to design the pedestrian bridge for the Strength I, Strength III, Strength

V and Service I load combinations due to the conditions which the structure will be subjected to.

Due to the fact that the AASHTO load combinations do not account for snow loading, and that the

proposed pedestrian bridge is located in Toledo Ohio, which receives on average 37.1 inches of per

year (http://en.wikipedia.org/wiki/Climate_of_Toledo,_Ohio) the ASCE load combination standard (Leet)

was consulted and a snow load factor was added to the Strength III and Service I AASHTO load

combinations (please see Appendix B: page 61-62 for all load combination, load factor and

importance factor calculations).

http://en.wikipedia.org/wiki/Climate_of_Toledo,_Ohio


SAP2000 Analysis

After laying out the proposed through truss bridge design in SAP2000 and inputting all joint loads

and load combinations as previously described, a complete analysis was ran on the truss. Using the

maximum axial forces in each member type, which were obtained from the SAP2000 analysis output,

the various members of the through truss were sized accordingly. Please see Table 3 on page 63 of

Appendix B for the maximum axial force in each respective member type and pages 64-66 of

Appendix B for the allowable strength checks. Listed below are the selected member sizes and

shapes for the through truss:

Through Truss Design - Member Sizes

- Top Cord = 12” x 12” x 5/8” HSS (Hollow Structural Section)

- Bottom Cord = 12” x 12” x 5/8” HSS

- Vertical = 12” x 12” x 3/8” HSS

- Diagonal = 12” x 12” x 3/8” HSS

- Floor Joist = 12” x 12” x 3/8” HSS

- Roof Truss = 2” x 2” x 1/4" HSS

- Wind Bracing = 1” Diameter Cable

Per Section 5 of the Modifications for AASHTO LRFD Bridge Design Specifications to Incorporate

or Update the Guide Specifications for Design of Pedestrian Bridges, the maximum allowable

vertical deflection due to the unfactored pedestrian live loading is 1/500 of the span length. The

maximum allowable horizontal deflection due to the unfactored wind loading is also 1/500 of the

span length. Accounting for the 150’-0” designed span length the allowable vertical deflection due

to the unfactored pedestrian live loading as well as the allowable horizontal deflection due to the

unfactored wind loading is 0.3’ (please see Appendix B: page 84 for deflection calculations) .

As can be seen below in Figure 14, the maximum vertical deflection due to the unfactored pedestrian

live loading is -0.1025’ (the U3 value) which is less than the allowable of -0.3’ according to

AASHTO Section 5 as stated above.

Figure 14: Maximum Unfactored Pedestrian Live Loading Deflection


As can be seen below in Figure 15, the maximum horizontal deflection due to the unfactored wind

loading is 0.0698 (the U2 value) which is less than the allowable of 0.3’ according to AASHTO

Section, as stated above.

Figure 15: Maximum Unfactored Wind Loading Deflection

After running a modal analysis on the bridge in SAP2000 it was determined that the horizontal

frequency of the structure is 0.518520 Hz (mode 1 of 2) and that the vertical frequency of the

structure is 0.518728 Hz (mode 2 of 2), both of which can be seen in Figure 16 below.

Figure 16: Horizontal and Vertical Frequencies of Bridge

Per equation 6-2 in Section 6 of the Modifications for AASHTO LRFD Bridge Design Specifications

to Incorporate or Update the Guide Specifications for Design of Pedestrian Bridges, the dead load

weight of the supported structure must be greater than the calculated value of 150.1150 Kips (please

see Appendix B: page 88 for vibration calculations). The sum of the assembled joint masses (dead

weight) obtained from the SAP2000 analysis is 422.7912 Kips which is greater than the 150.1150

Kips required according to AASHTO equation 6-2, therefore the frequency of the bridge meets the


minimum AASHTO vibration standards for fundamental frequency (please see Table 6 in Appendix

B: pages 85-87 for the assembled joint masses).

Camber

The bridge is to be fabricated with 8” of camber at the midpoint of the span. The specified camber

will account for all dead and live loading deflections and ensure that a sag situation is never

encountered. As can be seen below in Figure 17 (the U3 value), the maximum deflection occurs

under the Strength I load combination and has a value of -0.451’ (please see Table 7 in Appendix B:

pages 89-97 for the load combination deflections).

Figure 17: Required Camber Due to Maximum Deflection

6.3 - Welded Connections

A basic fillet weld connection was designed for a vertical t-connection at the midpoint of the truss

span using the element forces for frame 572 obtained from the SAP2000 analysis (please see Table 3

in Appendix B: page 63). Using the Table 3 values obtained from the SAP2000 analysis the axial

force, shear forces, moment forces and torsion values were calculated to obtain the resultant force.

The resultant force was then divided by the area of the throat (thickness of the frame member) to

obtain the stress across the weld for the strength I load combination (please see weld calculations in

Appendix B: pages 67-77). The calculated stress across the weld of 7.48 ksi, was checked against

gross allowable stress in AASHTO 6.13.9.2.4b-1 (please see Appendix B: pages 67-68) Fillet weld

connections are typical at all vertical t-connections.

All other connections will be full penetration groove welds. Full penetration groove welds have

strength equal to the strength of the frame members. A final check was conducted for fatigue in both

the fillet welds and the full penetration groove welds. The fatigue stresses were calculated for the

pedestrian live load and the wind load fatigue cycles for frame 572 from the SAP2000 analysis

(please see Table 3 Appendix B: page 63). The fatigue stresses were then checked against the

allowable fatigue resistance for both the pedestrian live load and the wind load cycles (please see

Appendix B: page 67-77 for weld calculations).


6.4 - Bridge Abutment Design

The bridge abutments have been designed for a drilled shaft deep foundation. Due to the poor soil

conditions as stated previously in the report, it is necessary to take the drilled shaft abutments to a

depth of 75’-0” to reach the suitable soil conditions of very stiff lean gray clay, see soils report

(Appendix A: pages 42-45). The calculated working load (Qw) was obtained from the SAP2000

analysis output for the joint reactions (please see Table 8 in Appendix C: page 99). The largest joint

reaction in the gravitational (z-axis) direction, which was given by the strength I load combination

(239.543 kips) was used as the Qw value in the abutment design. An additional 11.61 kips was added

to the working load for the weight of concrete making up the bridge seat of the abutment, due to the

fact that it was not accounted for in the SAP2000 analysis. Thus, giving a final Qw value of 251.144

kips. The unconfined compressive strength of the soil by layer, taken from the soils report, was used

as (qu). The undrained shear strength of the soil (cu) was obtained by dividing the unconfined

compressive strength by two. With the information from the soils report and the SAP2000 analysis

the following procedure was followed for the design of the bridge abutments.

Determine an adequate diameter of the shaft (Ds)

Determine the net ultimate point load-carrying capacity (Qp)

Determine the ultimate skin resistance (Qs)

Calculate the factor of safety with respect to the working load (F.S)

Thus, it was determined using the above procedure that two 4’-6” diameter drilled shafts at a depth of

75’-0” in the ground are needed per abutment (please see Appendix C: pages 100-101 for

claculations).

The above ground abutment column was design separately from the drilled shaft foundation and will

be tied together with re-steel. The abutment column was designed as a round spiral column with an

ultimate axial load (Pu) of 479 kips. Therefore, the above ground abutment column has a diameter of

1’-3” and height of 13’-6” above the ground. There are six #7 bars used for the vertical reinforcing

with #3 spiral ties at 2” spacing. The six #7 bars extend into the 4’-6” drilled shaft to a depth of 20’-

0”, where the #3 spiral tie spacing becomes 12”. The bridge seat of the abutment is 2’-0” wide, 3’-

6”deep and 18’-0” long. See Appendix C: page 102-103 for abutment design calculations. Also, see

Figure 18 on the following page for a cut section of the bridge abutment design.

Due to the fact the bridge abutment is within 30’-0” of Douglas Road, a 42 inch high Test Level 5

(TL-5) Roadside Barrier will be constructed to account for vehicle collision force per AASHTO

section 3.6.5.1.


Figure 18: Bridge Abutment Cut Section

6.5 - Ramp Design

The approach ramps leading up to the bridge span across Douglas Road are required to be accessible

to pedestrians, bicyclists, and handicapped individuals. Therefore, the approach ramps have been

designed to meet all ADA and bicycle requirements. The slope of the ramp is 8%, which is less than

the maximum slope of 1:12 (8.33%) written in Article 4.8.2 of the ADA Accessibility Guidelines.

Also, according to Article 4.8.2 of the ADA Accessibility Guidelines the maximum rise for any run

shall be 30” (2’- 6”) before a landing is required. All landings shall be level and have the following

features according to Article 4.8.4 of the ADA Accessibility Guidelines:

The landing shall be at least as wide as the ramp run leading to it

The landing length shall be a minimum of 60”

If ramps change direction at landings, the minimum landing size shall be 60” by 60”

To meet the above ADA requirements for accessible landings, the ramp has been designed to have

16’-0” x 5’-0” landings every 31’-3”. See Figure 19 on the following page for cut section of the

ramp design.


Figure 19: Ramp Design Cut Section

Due to the space limitations on the Engineering Campus a curved ramp design was necessary. The

ramp curve was required to accommodate the horizontal alignment of bicyclist coming into and out

of the curve. Unlike an automobile, a bicycle must lean while cornering to prevent it from falling

outward due to the generation of centrifugal force. The balance of centrifugal force due to cornering,

and the bicycle’s downward force due to its weight, act through the bicycle/operator’s combined

center of mass and must intersect a line that connects the front and rear tire contact points.

If bicyclists pedal through sharp turns and lean too far, the pedal will strike the ground because of a

sharp lean angle. Although pedal heights are different for different makes of bikes, the pedal

generally will strike the ground when the lean angle reaches about 25o. However, casual bicyclists

usually do not like to lean too drastically, and 15-20o is considered the maximum lean angle.

Assuming an operator who sits straight in the seat, a simple equation can determine the minimum

radius of curvature for any given lean angle given by the AASHTO Guide for the Development of

Bicycle Facilities. Thus, the curve was designed using the maximum design speed of 20 mph given

in the AASHTO Guide for the Development of Bicycle Facilities with a lean angle of 15o. With

these given design conditions the radius of curvature was calculated to be 100’-0” (please see

Appendix D: page 105 for calculations). The railing designs for the ramp meets the AASHTO

Bridge Design Specifications for both pedestrian and bicycle railings. Both AASHTO Article 13.8.1

and 13.9.1 state that the height of a pedestrian/bicycle railing shall not be less than 42” measured

from the top to the walkway/riding surface. The railings are design to be 54” in height with a grab

bar at 42” for pedestrians.

6.5.1 - Ramp Materials and Construction

The above ramp design will be constructed using the following materials: geofoam, pre-cast wall

panels, concrete slab, and steel pipe railings. Geofoam or foam-control expanded polystyrene block

(ESP Blocks) are a cellular plastic material that are strong, but have a very low density. They are


manufactured in block form and meet ASTM standard specifications (see geofoam technical data in

Appendix D: pages 106-109). Geofoam blocks are available in a wide range of types and sizes to

provide control of structural integrity and cost effectiveness.

The geofoam fill application for this bridge design project was initially explored due to the poor soil

conditions at the proposed site. For this specific reason the design team is proposing to use geofoam

fill for the ramp embankment. This primary application as fill material will minimize settlement, as

opposed to using soil, in which consolidation of the sub grade will take place over time due to the

self weight of the soil fill and the weight applied from the concrete slab. Large blocks of geofoam

are commonly used in geo-technical applications because it is lightweight, stable, evenly distributes

loading and is an excellent insulator. The minimization of settlement also enables buried utilities to

remain in-place, eliminating possible interruption, replacement, or relocation.

Another important use of geofoam in the bridge design is to improve the stability of the ramp

embankments. This application of geofoam eliminates stability concerns at the ramp embankments

and bridge abutments. This is due to the reduced lateral loads, allowing for vertical wall construction

without tiebacks. Geofoam gives an additional construction advantage, since it can be installed more

rapidly than other materials and even reduce construction time by up to 75 percent.

The ramp embankment has been designed as a pre-cast wall panel system. The pre-cast panel’s

ability to withstand significant differential settlements without loss of structural integrity, rapid

predictable construction, and architectural quality finishes make precast walls a cost effective choice.

The pre-cast panel walls are designed to be mechanically tied to the concrete slab by threaded

reinforcing bars placed in both elements and held together by threaded couplers. This connection

system has also been used for the I-15 Reconstruction Project in Salt Lake City, research provided by

Syracuse University (http://geofoam.syr.edu/GRC_i15.asp). There are various pre-cast panel wall

options and the panels can be customized to match the limestone veneer on Main Campus.

A mechanically stabilized earth (MSE) wall with reinforcing ties and the use of a light weight

aggregate fill (Solite) is an alternate option to reduce the initial cost of the ramp embankment. Due

to the poor soil conditions a settlement analysis would be required before implementation of this

alternate option. This alternate ramp embankment option has been implemented in the cost analysis.

While it will still be aesthetically pleasing it will not be possible to match the campus limestone for

this option. Please see Appendix D pages 110-111 for the Solite product specifications.

The concrete slab was designed using a 6” one-way slab design for both the ramp and bridge

applications. The design includes primary flexural reinforcing and transverse direction

reinforcement for shrinkage and temperature control. The 6” slab is to be reinforced with #3 bar

primary flexural steel at 8” spacing and a depth of 4” within the slab. The #3 bar transverse steel at

10” spacing is to be place above the primary flexural steel and it’s depth within the slab is not critical

(please see Appendix B: pages 52-53 for concrete slab calculations).

https://bl2prd0102.outlook.com/owa/redir.aspx?C=9494b91cc1554ec8a288d2efb2ad2ad4&URL=http%3a%2f%2fgeofoam.syr.edu%2fGRC_i15.asp


The ramp railings will be constructed of steel pipe and meet all AASHTO requirements for

pedestrians and bicycles as stated in the previous section. Please see Figure 20 below for railing

details and dimensions.

Figure 20: Railing Dimensions

An overall cut section of the ramp can be seen below in Figure 21.

Figure 21: Ramp Cut Section


7.0 - Alternative Design Options:

Due to the proposed abandonment of the CSX Toledo Backside Railroad tracks, the second design

option is the proposed design and the first design option is the alternative design if the tracks are to

remain open and in-service. If the CSX railroad abandonment is not taken into account and the

railroad is deemed active, the 23’-0” vertical clearance, as stated above from the rail line to the

bottom of the overhead bridge structure will be maintained in the design. To satisfy the tight space

requirements, two towers with a floor height of 25’-0” above the ground will be erected to provide

pedestrian access to the bridge span. These towers will both have elevators, per section 4.10 of the

ADA Accessibility Guidelines for Building and Facilities, and shall be located on the east and west

sides of Douglas Road parallel to Oakwood Avenue. The steel through truss bridge will be simply

supported by two intermediate columns and the two main end towers. The towers on the east and

west sides of Douglas Road will each have dimensions 23’-0” x 39’-0” x 43’-0”. The east and west

side intermediate support columns will each have dimensions 6’-0” x 16’-0” x 41’-0”. The distance

from the main towers on each side to the intermediate towers is 85’-6”. The distance from the inner

edge of the two intermediate towers is 124’-0” (Figure 22). See drawing 8 of 8 for details of the

alternative bridge design.

Figure 22: Elevation View of Alternative Bridge Design

The transmission power line clearances stated in the constraint section above were also met when

designing the alternative bridge. As with any construction project, there are many pros and cons that

come along with the alternative design. While the cons of the alternative design outweigh the pros,

the alternative design still does satisfy the primary objective of safely transporting pedestrians across

Douglas Road and integrating the architectural design themes of The University of Toledo Main

Campus and the Engineering Campus.

7.1 - Geothermal Heating

In order to heat and cool the bridge structure and promote a sustainable design, a geothermal system

will be used in the alternative design option. What drives a geothermal system is a ground-source

heat pump that cycles a R-22 Freon chemical through an underground closed piping loop. The R-22

Freon that travels through this loop utilizes the soil temperature to warm and cool the heat pump’s

refrigerant. The major advantage with heat pumps is they do not have to create heat like a

conventional furnace, they harvest existing heat from the ground, and this is where the savings comes


into effect. A ground-source heat pump is able to tap a stable heat source due to its underground

piping. Soil 4’-0” to 6’-0” below the frost level stores the sun’s energy at a constant level, with the

temperature directly related to the latitude. An average temperature of 55o can be assumed for the

northeastern United States. This means the geothermal system needs to boost the indoor temperature

a measly 15o to reach a comfortable indoor temperature during the winter months. When this is

compared to the 40o to 60o differential that an air-to-air heat pump may handle, and an even higher

differential for standard furnaces, and the cost saving potential is very clear.

The geothermal system can also be used for air conditioning during the summer months. In a

conventional air conditioning system the compressor has to labor in the sweltering outdoor heat and

use the hot air is it cooling medium. A ground-source heat pump used in a geothermal system is

located indoors using the ground temperature as its cooling medium. This results in a 20% to 40%

savings over conventional air conditioners and heat pumps.

Since the proposed project site has limited available space, a vertical closed-loop system will be

used. A well driller will drill several holes with casings 150’-0” to 200’-0” deep. Vertical, closed-

loop systems are more efficient, but require more polyethylene piping than other geothermal systems.

Drilling costs are also higher. Total cost for a geothermal vertical, closed-loop heating and cooling

system is $20/ sq. ft. This includes all mechanical equipment and the heat exchanger. Figure 23

represents the vertical, closed-loop system that will be used in the alternative design

(www.popularmechanics.com).

Figure 23: Vertical, Closed-Loop Geothermal System.

(Source: http://www.popularmechanics.com/how_to_central/home_clinic/1274631.html)

http://www.popularmechanics.com/how_to_central/home_clinic/1274631.html


8.0 - Estimated Cost of Proposed Design:

A cost analysis for the proposed bridge design with a geofoam embankment and an alternate light

weight aggregate fill embankment (Solite) were performed as part of this design investigation for the

University of Toledo College of Engineering. Please see Table 1 below for the cost analysis of the

proposed bridge design.


9.0 - Estimated Cost of Alternative Design:

An alternate cost analysis was performed to propose a bridge design to the University of Toledo

College Of Engineering for the possibility that the CSX Toledo Backside Railroad Line is not

abandonment as proposed. In addition to the cost of the structure there will also be a yearly elevator

maintenance cost of $4,800.


10.0 - References

“2005 Traffic Flowmap”. TMACOG. Web. 31 Aug. 2009.

<http://www.tmacog.org/Transportation/Traffic%20Flow/Flow%20map%2005.pdf>.

AASHTO LRFD Bridge Design Specifications, Customary U.S. Units, 4th Edition (Loose Leaf).

Washington, DC. American Association of State Highways and Transportation Officials,

2009. Print

“Climate of Toledo, Ohio”. Wikipedia, The Free Encyclopedia, 17 July 2009. Web. 10 Sept. 2009.

<http://en.wikipedia.org/wiki/Climate_of_Toledo,_Ohio>.

Das, Braja M. Fundamentals of Geotechnical Engineering. Belmont: Thomson-Engineering, 2004.

Print.

Das, Braja M. Principles of Foundation Engineering. Belmont: Thomson-Engineering, 2003. Print.

Foam-Control EPS Geofoam. AFM Corporation. Web. 27 Oct. 2009.

<http://www.geofoam.com/>.

"Geothermal Heating -." Popular Mechanics. Web. 11 Sept. 2009.

<http://www.popularmechanics.com/how_to_central/home_clinic/1274631.html>.

"Guide for the Development of Bicycle Facilities." American Association of State Highway and

Transportation Officials, Fall 1999. Web. 19 Oct. 2009.

<http://www.communitymobility.org/pdf/aashto.pdf>.

Leet, Kenneth, and Chia-Ming Uang. Fundamentals of Structural Analysis (Mcgraw-Hill Series in

Civil and Environmental Engineering). New York: McGraw-Hill Companies, 2004. Print.


McCormac, Jack C. Design of reinforced concrete. 8th ed. New York: Wiley, 2008. Print.

Murphy, Ph.D., P.E., Thomas P., and John M. Kulicki, Ph.D., P.E. Modifications for AASHTO LRFD

Bridge Design Specifications to Incorporate or Update the Gude Specifications for Design of

Pedestrian Bridges. Tech. Mechanicsburg: Modjeski and Masters, Inc, 2009. Print.

“Public Project Information”. CSX Transportation Inc., 8 May 2009. Web. 29 Sept. 2009.

<http://www.csx.com/share/media/media/docs/CSX_Public_Project_Manual-REF21857-

REF22268.pdf>.

Segui, William T. Steel Design. 4th ed. Belmont: Thomson-Engineering, 2006. Print.

“Solar Angle Calculators”. Solar Trading Post LLC. Web. 7 Oct. 2009.

<http://solartradingpost.com/solar-angle-calculators.html>.

Steel Construction Manual, 13th Edition (Book). New York: American Institute of Steel

Construction, 2006. Print.

“Use of Geofoam for I-15 Reconstruction in Salt Lake City, UT”. Syracuse University Geofoam

Research Center, Spring 2000. Web. 27 Oct. 2009. <http://geofoam.syr.edu/GRC_i15.asp>.

Welcome to Glasswebsite 3.0. Glass Association of North America. Web. 28 Sept. 2009.

<http://www.glasswebsite.com/>.


Appendix A:

Site Conditions

CSX Transportation, Inc. Proposed Railroad Abandonment…………………………..…………33-36

First Energy Transmission Line Clearance Requirements………………………………………..37-41

TTL Associates, Inc. Soils Report………………………………………………………….……..42-45


Appendix B:

Through Truss Bridge Design

Glass Association of North America: Approximate Weight of Architectural Flat Glass…………….47

GE Energy: GEPVp-200 Solar Panel Product Data………………………...…………………….48-49

Solar Panel System: Design Calculations………………………………………………………...…..50

Solar Panel System: Power Generation and Cost Savings Calculations……………………………..51

Slab Design………………………………………………………………………………..………52-53

Horizontal Wind Pressure………………………………………………………………………….....54

Tributary Area Loading Calculations…………………………………………………………….55-59

Vehicle Loading Calculations………………………………………………………………………...60

Required Load Combinations…………………………………………………………..…………61-62

Table 3: Frame Element Forces………………………………………………………………………63

Through Truss Bridge Member Sizing……………………………………………………………64-66

Welded Connection Calculations………………………………………………………………....67-77

Table 4: Unfactored Pedestrian Live Load Joint Displacements………………………..………..78-80

Table 5: Unfactored Wind Loading Joint Displacements……………………………...…………81-83

Deflection Calculations……………………………………………………………………………....84

Table 6: Assembled Joint Masses………………………………………………………...………85-87

Vibration Calculations………………………………………………………………………………..88

Table 7: Load Combination Joint Displacements……………………………………………...…89-97


http://www.glasswebsite.com/publications/reference/FGMD%20010408%20%20Approximate%20Weight%20of%20Architectural%20Flat%20G

lass.pdf

http://www.glasswebsite.com/publications/reference/FGMD%20010408%20%20Approximate%20Weight%20of%20Architectural%20Flat%20Glass.pdf

http://www.glasswebsite.com/publications/reference/FGMD%20010408%20%20Approximate%20Weight%20of%20Architectural%20Flat%20Glass.pdf


http://www.mrsolar.com/pdf/ge/GE-200.pdf

http://www.mrsolar.com/pdf/ge/GE-200.pdf


Appendix C:

Abutment Design

Table 8: Joint Reactions………………………………………………………………………………99

Drilled Shaft Pile Design Calculations……………………………………………………..…..100-101

Abutment Column Design Calculations..………………………………………………………102-103


Appendix D:

Ramp Design

Radius of Curvature Calculations (East Ramp)……………………………………………………..105

GeoFoam Technical Date………………………………………………………………………106-109

Solite Specifications……………………………………………………………………………110-111


http://www.geofoam.com/downloads/brochure/Foam-Control-EPS-Geofoam-TechData.pdf

http://www.geofoam.com/downloads/brochure/Foam-Control-EPS-Geofoam-TechData.pdf


Appendix E:

Design Team Resumes

Ryan Askins…………………………………………………………………………………………113

Chris Beckert………………………………………………………………………………………..114

Josh Dobrzeniecki………………………………………………………………………………...…115

Kyle Kreft………………………………………………………………………………………...…116

Nick Zenk…………………………………………………………………………………………...117


Appendix F:

Detailed Drawings

Title Sheet…………………………………………………………………………..………Sheet 1 of 9

Existing Conditions……………………………………………………….………………..Sheet 2 of 9

Demolition Plan…………………………………………………………………………….Sheet 3 of 9

Proposed Plan View………………………………………………………………………..Sheet 4 of 9

Proposed Elevation View…………………………………………………………………. Sheet 5 of 9

Construction Details……………………………………………………….……………….Sheet 6 of 9

Construction Details…………………………………………………….………………….Sheet 7 of 9

Construction Details………………………………………………….…………………….Sheet 8 of 9

Alternative Design…………………………………………………………….……………Sheet 9 of 9

Final report design of a pedestrian bridge - fall 2009

Engineering

Transcript of Final report design of a pedestrian bridge - fall 2009