Suspension Bridges VS Beam Bridges
Engineering Scout Squad
City College of New York
March 5, 2024 – April 11, 2024
Budget: $1,075.00
Abstract
Bridges are critical infrastructures that facilitate transportation over obstacles such as rivers and highways. Suspension bridges and beam bridges are two distinct types of bridges that use different structural designs. Suspension bridges use cables attached to support pillars to transfer load, whereas beam bridges depend on supports beneath the bridge surface. Both are needed in specific conditions, however, it is important to know which one is more reliable, stronger, and overall better to provide a safe path to travel. The purpose of this research is to compare side by side the structural virtue of suspension and beam bridges under load scenarios to determine which design is superior. The study is carried out by simulating both bridge types with rudimentary models and testing them by increasing loads till failure. The experiment is conducted at a smaller scale however, it has the fundamentals needed to make strong affirmations. The experiment establishes which bridge style can withstand the most weight before collapsing, providing important insights into bridge engineering. The research technique entails building models of each bridge type, performing load testing, collecting data, and assessing the results. Suspension bridges are expected to have greater load-bearing capability than beam bridges due to their design characteristics.
Introduction
Bridges are structures built to traverse notably over rivers and other large bodies of water or highways. This research will compare two unique bridge designs and the amount of weight they can handle before giving away. These two designs are the suspension bridge and the beam bridge.
Bridges must be supported in one way or another to withstand the stress caused by cars, wind, earthquakes, and other such factors. A suspension bridge is a particular bridge design that utilizes cables anchored to sets of pillars that pull the bridge deck and offset the stress towards the anchors. The force on the bridge itself is being pulled, while the anchors are being compressed. On the other hand, a beam bridge has supports below the bridge deck which hold it directly, meaning that the bridge deck must solely rely on the supports below it to alleviate any stress.
Using the data found during this research will help determine the proper circumstances for each bridge. This experiment is meant to provide insight into the load limits of the two bridges and will be tested by continuously adding weight in the load tester and deriving the speed at which the bridge fails. The experiment will prove that the suspension bridge will require a heavier load to fail compared to the beam bridge.
The results of this research will help in developing stronger materials and provide valuable data for further analyses. The data collected can be used as a benchmark for the materials used within this experiment. They can be built upon to develop better-suited alloys and composites for bridge engineering.
Literature Review: The journals by both Gregor P. Wollmann and Osamu Yoshida both discuss the actual build and infrastructure of the bridge while the article by Lin Ma mentions both the infrastructure of the bridge as well as mention how different loads of cars impact its integrity.
The article “Robustness Evaluation of Aerodynamic Flutter Stability and Aerostatic Torsional Stability of Long-Span Suspension Bridges” is similar to the one above about focusing on the actual build and infrastructure of the bridge but specifically in the case of wind resistance for severe cases like natural disasters. Every bridge needs to be wind-resistant to be considered stable which is why there are videos online of bridges swaying but not falling.
Annotated Bibliography:
Ma, Lin, et al. “The Theoretical Impact Factor Spectrum for Highway Beam Bridges.” Journal of Bridge Engineering, vol. 26, no. 12, Dec. 2021, https://ascelibrary.org/doi/10.1061/%28ASCE%29BE.1943-5592.0001800.
This journal introduces the variable of different vehicle loads. The purpose of this journal is to
expand the random load of a bridge into an expression in both time and frequency domains. The
article included an abstract, introduction, and analysis of the construction period of the beam
bridge. Equations and visuals were provided to represent the theoretical formula of the impact
factor (IM) spectrum.
Yoshida, Osamu, et al. “Structural Characteristics and Applicability of Four-Span Suspension Bridge.” Journal of Bridge Engineering, Sept. 2004, https://ascelibrary.org/doi/abs/10.1061/(ASCE)1084-0702(2004)9:5(453)?casa_token=mb1GiePdCoIAAAAA:JJjCTDx2GwM5J9NzRhAyCeI6JTSaA4rOpKVTZ18n5wXxYh6wAIBaG75KnlIf4IKnPW-n1MJxSQ.
This journal discusses a study on the deformation characteristics of a four-span suspension bridge with two main spans of 2,000 meters each. The study finds that the rigidity of the center tower primarily influences the deformation behavior. Key properties such as bending and torsional rigidity of the girder, sag ratio, and dead load are examined. Furthermore, it goes in depth by providing illustrations and calculations to estimate the integrity of the bridge throughout the study.
Wollmann, Gregor P. “Preliminary Analysis of Suspension Bridges.” Journal of Bridge Engineering, Aug. 2001,
https://ascelibrary.org/doi/10.1061/%28ASCE%291084-0702%282001%296%3A4%28227%29.
Dr. Wollmannis a doctor and professor in structural engineering. He was awarded the 2003 Arthur M. Wellington Prize by the American Society of Civil Engineers. In this journal, he analyzes the fundamental equations of suspension bridges based on the deflection theory and presents a method solution for said equations. It also touches upon pylon and girder stiffness.
Xia, Qing, and Yaojun Ge. “Robustness Evaluation of Aerodynamic Flutter Stability and Aerostatic Torsional Stability of Long-Span Suspension Bridges.” Applied Sciences (2076-3417), vol. 13, no. 24, Dec. 2023, p. 13136. EBSCOhost, https://doi-org.ccny-proxy1.libr.ccny.cuny.edu/10.3390/app132413136.
This article potentially tests the robustness of really long suspension bridges to see if it will be wind-resistant. It wants to figure out what particular design would be able to withstand harsh wind conditions. The evaluation process in this article helps to figure out the outcomes of bridges during natural disasters such as tornadoes and hurricanes. Though it doesn’t help for this experiment, in real life, this would be considered an actual factor in whether suspension bridges or beam bridges would be better suited
Project Narrative
The experiment will be conducted with models of the two bridges, three trials will be held to determine the conclusion of this experiment.
The procedure for the beam bridge is as follows:
Ten straws will be cut to the same length, leaving ten long and short pieces. Two of the shorter pieces are then cut to a length of three centimeters each. Two long straws are taped directly on one end while the other end is taped with a short piece in between. This acts as the pylon and will be used to support the bridge deck. Two of these pylons are constructed and taped to two pieces of furniture at the same height with the short straws on the bottom and the narrow end pointing up. A long straw will then be inserted between these pylons to act as the bridge deck. This completes the construction of the beam bridge model.
The load tester is constructed using a cup. A paperclip would then be unfolded into a V-shape with the ends going through two holes poked in the cup. Another paperclip is used as a hook to suspend the cup from the bridge deck. The load is added using pennies, where they are placed into the cup one at a time until the bridge deck collapses. The number of pennies is recorded in a table and the experiment continues by replacing the bridge deck with a new straw. Once three trials have been conducted and the number of pennies has been recorded, the average will be found and recorded.
Personnel
Nathan Hounkpevi is responsible for the experimental aspect of the project. As well as creating the time frame and budget charts. Diego Borbon is in charge of the annotated bibliography and finding credible sources. Lucas Ringwald wrote the introduction and project narrative, providing the background, methods used, and significance of the research conducted. Javier Pujols wrote the abstract as well as the overall formatting and organizing of the paper.
Budget
| Item | Amount | Price | Description |
| Straws | 50 count | $2.80 | The straws are the main material that will be used for making the bridge |
| Tape | 1 | $3.00 | The tape will be used to connect the straws to the chairs |
| Scissors | 1 | $4.83 | The scissors will be used to cut the straw to cut the straws and thread to the needed length |
| Chairs | 2 | $30.00 | Will be used as the land for both sides of the bridges |
| Thread | 1 | $1.97 | Will be used as the cables for the suspension bridge |
| Tape measure | 1 | $5.63 | Will be used to measure the thread to its needed length and to measure the distance between the chairs for the bridge |
| Notebook | 1 | $1.29 | Will be used to record the information gained from the experiment |
| Pens | 60 count | $6.79 | Will Be used to record the information gained from the experiment |
| Pennies | 150 | $1.50 | Used as the weight added to the cup |
| Cup | 20 count | $4.00 | Will be holding the weight of the pennies in this experiment |
| Workspace | $50 an hour (3 hours) | $150.00 | Where experiment will be conducted |
| Payment | 4 people – $18 an hour (12 hours) | $864.00 | Salary |
| Total | $1,075.00 |
Timeframe
| 3/12 | 3/14 | 3/17 | 3/19 | 3/23 | 3/26 |
| Experiment (completed) | Finish budget section | The first draft is due! | Work on Literature review | Final draft due | |
| Data (completed) | Start Introduction | Feedback based revision | Add final draft to website | ||
| Continue research | Continue research / start annotated bib | ||||
| Start different sections of the proposal | Start project narrative | ||||
| Start budget section | |||||
