Design of Pedestrian Bridge

Editor's Notes

• #2: Industry representatives, faculty, classmates, students, friends and family, thank you for attending our senior project presentation.What is a bridge?Is it just a structure providing passage over an obstacle? Over the course of this project, for us, the definition of a bridge has expanded beyond its traditional meaning. This project has bridged theory and practice, multiple disciplines, and different expertise and personalities
• #3: I am Damian Allen, the project manager for this project and this is the team. Emanual Alforja Arash PiaMichael OlsonRobert BatemanThomas GribbleErik EllingsenSayed Masood Ul-HaqueWe did not know each other prior to this project. We all came from different backgrounds, and we all have different passions in civil engineering. Until the last week, we got along just great. On a serious note, over the course of this project, we have worked together as one team. We are excited to share with you our work.
• #5: The project site is on campus and is an open space between two engineering buildings. Looking at the two buildings you can see a significant difference in their architectural styles, which presented some aesthetic considerations.
• #11: The important information obtained from the preliminary research was the required fire access height clearance of 13.5’ and width clearance of 25’, bridge live load deformations were limited to L/500, lateral deformation was maximum H/200, storm drain locations were identified, and live load criteria was set to 85 psf.
• #12: Geospatial study was an early part of the design process. This included conducting a site survey and from that, generating a digital terrain model.
• #13: The purpose of site survey was to create a DTM so that we could extract all necessary information for the project. This includes topographic data, existing objects, building and site elevations, and the exact distance between the two buildings. The survey was performed using a Geodimeter, which accurate to __. Other basic tools such prism and surveying tape were used. We surveyed over 300 points to generate our 3D model.
• #15: Robert BatemanplatemanDuring the preliminary geotechnical investigation, we conducted a subsurface desk study, two exploratory borings next to buildings 9 and 17, and laboratory testing. Based on obtained information, we prepared a preliminary geotechnical investigation report.
• #16: Before drilling holes and testing soil, we collected site specific information. Documents found from sources such as the USGS provided seismic, geologic, and topographic data. This helped us to locate local faults, such as the San Jacinto and San Gabriel faults, identify expected soil type, determine liquefaction potential, and evaluate historical and archeological significance of the site.(CIRCLE THE SITE AREA, ADD LEGEND)RobertAs with any geotechnical investigation, ours began with a preliminary desk study. Through geologic, hydraulic, and geotechnical data from USGS we wer able to classify our surrounding subsurface conditions. Geologic maps indicated nearby fault lines, mainly the San Jacinto and San Gabriel, which will be significant in our seizmic design critera. Further research concluded a preliminary classification of the soil which was indicated as an under consolidated sandy clay and is considered pre quaternary. This site is also prone to liquid faction effects in the north which escaped the site area.
• #17: We prepared and presented a boring plan to facilities during their scheduled trades meeting and received approval. We also informed DiggAlert USA and received their approval. With the help of Dr. Kitch, we were able to use department drilling equipment to conduct two exploratory borings. Boring A was located in the planter next to Building 9 in the vicinity of a planned foundation, while Boring B was located in the grassy area adjacent to Building 17.
• #18: With the disturbed and undisturbed samples gathered from our borings, in depth geotechnical testing was performed in our lab to accurately classify our soil and retrieve the necessary parameters to conduct our footing design.
• #19: Our lab data confirmed our desk study that the soil is a normally consolidated sandy clay. Compaction would be required if spread footings were used. Our soil unit weight was 130 pcf, cohesion 600 psf, friction angle 24^, and soil bearing pressure 3900 psf.
• #21: Elevations, offset, drainage, building heights, existing usage, utilities == entire site plan + google earthSPAN/OFFSET5 foot offsetexplain contoursfire lane accessbuilding widthutilitiesbridge spanflow lines/pathcongregation area
• #26: These are the 4 structural systems we considered, state them.we immediately ruled out suspension, as a large monolithic tower would overpower the buildings and not fit in the architectural context, and would require deep foundations, difficulty of construction out of wood.
• #27: Developed and mass-produced by the Roman Empire, the arch is widely implemented in ancient and modern culture. An arch is a structural element that is able to transform its loading into compressional thrust, an ideal application for a timber structure.
• #28: The arch bridge design consists of two cross-angled arches that support a straight walkway and implements spacious seating areas for multifunctional use.
• #29: MasooOOOOOOoooooDDDD,In addition to adhering to the design criteria, the main objective of the beam concept was to have a design that was slender and sleek. These are some of the cross-sections and alignments sketches.beam system was attractive due to simplicity, streamline design, low material costs, and feasibility at the project site
• #30: The solution to the vertical clearance criteria was to provide a slight arch to the bridge. To reduce the size of the girders and meet the horz clearance criteria, we had four supports, two of which branch out shortening the unsupported span. This design was inspired by the natural beauty and strength of trees.The lateral resistance system included a braced frame located at building 9, and a moment frame at building 17. For intermediate deck support, beams were shaped to mimic the moment distribution for a simply-supported cantilever beam.
• #31: ERIKwhen evaluating the space truss system, our main objective was to optimize the space presented on the site. with ideal truss behavior, loads applied from any direction are translated axially through the frame members to the supports and foundation.
• #32: we developed a simply-supported cantilevered three-chord truss system. some of the problems encountered with this system were the constructability issues due to crossing members and joints receiving as many as 11 members.
• #33: As a group, we had a closed-ballot vote. based on a combination of aesthetics, feasibility, educational value, and design challenge that the system presented, the space truss was selected. based on a combination of aesthetics andfits the scope, good education tool, would be a challenge to design a 3D space truss
• #35: We experienced some design pains in this phase transition. There were some inherited problems with the space truss concept. We learned the value of building models vs. drawing models, as there can be gaps in the comprehension of structure function. We found when building the scaled model, there would be constructability issues, as there were many crossing members in the preliminary design. We also discovered that some of the joints created were receiving too many members at difficult angles. Before we could continue with design, we needed to optimize the it.
• #36: The factors that went into this optimized design included clearance for fire access, member demand, serviceability, and accessibility. The bridge required deflections that satisfied serviceability, and also allowed for the required clearance. In addition, sample calcs were done for the capacity of the material we planned on using, and had to keep our demand down. Also, the bridge required level landings at both ends and at the center of the bridge.
• #37: DAMIAnEPIPHANY!!! DUH!!!after numerous iterations of 3d modeling and analysis of different member configs, depths, and # of chords, the optimal space truss member config consisted of tetrahedral and pentahedral designs. these shapes are considered to be among the strongest shapes in geometry, which added to the rigidity of the structure.Evolution3 chords, 2 feet deep2. 3 chords, symmetrical tetrahedral, 1.5 to 3 feet deep3. 5 chords, symmetrical tetrahedral, 1.5 to 3 feet deep4. 5 chords, asymmetrical tetrahedral, 1.5 to 2 feet deep  winnarSequential speakersElevations/cross section/chord callouts
• #39: to help offset the torsional loading effects of the wing extensions, a gradual transition was made from nine nodes in the chord framing system to the concrete column supports. this located the centroidal line of the bridge. insert plan viewBridge elevations
• #41: put in max loadsaxial demand onlyasce load combos, worst case scenariocall out types of wood used
• #42: EMANUELPoints of Discussion:Benefits of using X-Lam Timber for Deck: visual appeal; increased strength; lighter weight compared to steel and woodExplain Manufacturer: KLH in Germany; Provided information packet; included Engineering PropertiesMethod of Selecting Product: for the largest panel size determine the required thickness and apply throughoutKLH Product: KLH TT-72-3S (VS) – 3 Layer 72mm or 2.8” thickness, Visual QualityOther Deck Consideration: spray on non-skid coating; butt-joint sealer options- extruded rubber or floor joint sealers; wood sealer
• #43: ROBERTwith the bridge design under completion the next step is to direct the load path from the bridge supports to the soil below, via the columns. however situated, these columns would have to the meet the objectives of being: 1. aesthetically pleasing and 2. able to transmit loads from the bridge supports resisting shear, torsion, and biaxial bending. prelim conceptual designs were made and what you see before you was chosen. as you can see, the irregular polygonal cross section mimics the rhombus pattern of the bridge creating aesthetic flow, and formwork construction was considered to be much cheaper and more efficient than the other designs. pca column was used to create the prelim dimensions and rebar choice, and was later confirmed by hand calculation.
• #48: MIKEMike is such a jerk. He likes boys. Since the beginning of this quarter he’s been cheating on his girlfriend with Arash. Mike wishes why California does not allow gay marriage.