A Failure of a Bridge
My bridge performed to an acceptable status, however, the unique suspension design I gave it did not even effect the model’s capabilities while testing it. If anything, the excess material that came with the suspension design simply added weight to the model that was unnecessary. Unfortunately, the excess material was not the biggest flaw of my bridge.
First off, the truss design did not have a clear flaw in it. In fact, the sturdy truss is mainly what allowed the bridge to last so long. By combining a Warren truss design with a parallel series of vertical support posts, the bridge was successfully able to distribute the weight to the support points. However, knowing that there would be no (or at least little) support where the suspension points were placed at the bottom of the bridge, I would have differed from the truss style I did use. With that said, a Howe truss design probably would have suited this bridge’s proportions to better with stand a failure.
Additionally, the truss is not the only part of the bridge where error can occur. Perhaps one of the more unrealistic aspects of this test is the compression that is exerted around the bridge by the strings connected to the load that are tied around the bridge. I did take this factor into account when building my bridge, but apparently I did not
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In reality, the bridge was designed to support weight that would be applied to two specific points, thus the concept of torque was not an immediate liability in the design process. Unfortunately, that is exactly why this bridge failed. There was enough weakness on one side of the bridge that the twisting forced a specific corner to bend inward. That then pushed the opposite side of that corner outward and the rest of the structure soon followed causing the entire bridge to fall to its side, a position that could not support the load it already
Without a concrete reason for the bridge's failure, every suggested reason was researched until proven incorrect” (Silver). There were many reasons that were suggested, but could not be proven correct due to the collapse. Wikipedia states that “A small crack was formed through fretting wear at the bearing, and grew through internal corrosion, a problem known as stress corrosion cracking.” The failure of the bridge was caused by a defect in one of the eye-bars on the north side causing the other side to collapse as well. “Stress corrosion cracking is the formation of brittle cracks in a normally sound material through the simultaneous action of a tensile stress and a corrosive environment.
The area of where the bridge was to cross the Ohio River was said to be one of the hardest places to build but came with some advantages. The section of the river had a solid rock base for the supporting pier to be built on. Since the engineers knew they could build a pier that would not settle they decided on a continuous bridge design. This design type distributes the weight so the steel trusses could be smaller and riveted together. This alone saved an estimates twenty percent of steel that was originally thought to be need to make the bridge cutting down the cost. The two continuous trusses span a collective 1,550 feet across the water. With addition of the north and south approach viaducts, for trains to go under the bridge, the superstructure’s total length is 3,463 feet. The bridge was made to hold two sets of tracks making the width 38 feet and 9 inches. The design called for 27,000 cubic yards of concrete and 13,200 tons of steel with some members being four foot square beams that span a distance of seventy feet. The design was the first step in a long process that would take several years to
The process of designing, building and inspecting the bridge had plenty of assumptions. Training on the strength of gusset plates would have mitigated those assumptions with expertise.
According to Suspension bridges: Concepts and various innovative techniques of structural evaluation, “During the past 200 years, suspension bridges have been at the forefront in all aspects of structural engineering” (“Suspension”). This statement shows that suspension bridges have been used for over 200 years, and that people are still using them today because they are structurally better bridges. This paper shows four arguments on the advantages of suspension bridges, and why you should use one when building a bridge. When deciding on building a suspension bridge, it has many advantages such as; its lightness, ability to span over a long distance, easy construction, cost effective, easy to maintain, less risk
Joseph B. Strauss, a famous designer of movable spans became interested in building a bridge at the Golden Gate so he submitted a proposal. His design was a hybrid structure that included a suspension span of 2,640 feet long along with a cantilevered truss span of 685 ft. on each end. However, his design was rejected by the public because they thought such a bridge would ruin the beauty of the area. Therefore, Strauss had to work with Othmar Ammann, Charles Derleth Jr., and Leon Moisseiff, consulting engineers, who together created a new design. They created a suspension bridge with a length of 4,000 ft. Their new design was approved by the U.S. War Department in 1930 and construction proceeded.
Compare with other types of bridges, suspension bridge can span the longest distance without using lots of material. However, if the issue of stiffness was not fully cosidered, vibration would be occurred on the bridge deck under high wind. A few week after the Tacoma Narrow Bridge was operated, the bridge start oscillation and its oscillation kept increasing day by day. Therefore engineers tried to build more cable between the bridge, but it is still unsuccessful. After four months the Tacoma Narrows Bridge was build, the bridgre which normally vibrated in a vertiacal motion, began to oscillate with the opposite side out of phase (torsional model), under the wind of 68 km/h. Due to the extremely violent oscillation, the failure bagan at the mid-...
The commission issued 15 conclusions that lead to the failure of the bridge. The commission found that Theodore Cooper and Peter Szlapka were directly responsible for the collapse. Peter Szlapka was the design engineer for the Phoenix Bridge Company and designed the chords that failed. Theodore Cooper was found responsible as well because he officially examined and approved the design. The Quebec Bridge and Railroad Company was also found responsible for failure to appoint an experienced engineer as chief engineer. The main reason for the collapse was poor design. Eventually the bridge became so heavy that it couldn’t even support itself. The bending and distortion of the steel was caused by the dead load of the bridge. The collapse can also be due to stubbornness and refusal to admit a mistake was made early on and didn’t want to redo all the plans. The Phoenix Bridge Company refused to believe their steel was bending and claimed that the distortions must have already been there before the steel was used to make the bridge. Also important factors such as increasing the span of the bridge were not taken into account and no new calculations were ever computed to change the
One of the most influential engineering discoveries in the past century was the ill-fated Tacoma Narrows Bridge. “Galloping Gertie” as she was known to local residents, the massive Washington state suspension bridge shook, rattled and rolled its way into the history books. Legendary in its time, the Tacoma Narrows Bridge held many records and drew tourists from around the world in its short life. However, the famous bridge is not known for its creative engineering or speedy construction, unfortunately the bridge was destined to fail. That failure in turn changed the way every building is constructed today as well as further man’s understanding of physics and the forces of nature. In this paper we will examine the history of the Tacoma Narrows Bridge from design to construction, the failure of the bridge, and ultimately the rebuilding project.
This all iron design made the bridge a lot heavier than it was designed for, which added more stress to the truss. This fact, by itself, wouldn’t cause any alarm. However, the bridge itself, was very poorly constructed. The members of the bridge were all different sizes, and they were not connected together properly. Due to the poor construction and eleven years of use, members of the bridge had started to bend due to the stress. Despite bridge engineers inspecting the bridge for eleven years, no one noticed these faults with the bridge. However, the ultimate cause of this collapse, was so tiny, only one of the investigators, after the collapse, noticed it. A tiny air hole was left during the construction of the bridge, “and grew with repeated stress over eleven years” (Escher, 2009). This hole would develop in a crack, due to the changing temperatures and the trains crossing it for over eleven years. This would weaken the overall strength of the bridge. The cold winter air and the weight of the train would ultimately prove to be too much, and the whole bridge came crashing
The Tacoma Narrows Bridge is perhaps the most notorious failure in the world of engineering. It collapsed on November 7, 1940 just months after its opening on July 1, 1940. It was designed by Leon Moisseiff and at its time it was the third largest suspension bridge in the world with a center span of over half a mile long. The bridge was very narrow and sleek giving it a look of grace, but this design made it very flexible in the wind. Nicknamed the "Galloping Gertie," because of its undulating behavior, the Tacoma Narrows Bridge drew the attention of motorists seeking a cheap thrill. Drivers felt that they were driving on a roller coaster, as they would disappear from sight in the trough of the wave. On the last day of the bridge's existence it gave fair warning that its destruction was eminent. Not only did it oscillate up and down, but twisted side to side in a cork screw motion. After hours of this violent motion with wind speeds reaching forty and fifty miles per hour, the bridge collapsed. With such a catastrophic failure, many people ask why such an apparently well thought out plan could have failed so badly?(This rhetorical question clearly sets up a position of inquiry-which iniates all research.) The reason for the collapse of the Tacoma Narrows Bridge is still controversial, but three theories reveal the basis of an engineering explanation. (Jason then directly asserts what he found to be a possible answer to his question.)
Where they went with John’s idea of putting the roadways lighter so there could be less stress on the cables. Even with his idea, an unexpected blast wrecked one caisson, a fire damaged another, and a cable snapped and crashed into the river. Despite the problems the construction still continued at a fast rate. It’s crazy how this bridge is the second busiest bridge in New York City.
Bridge scour is the removal of sediment such as sand and rocks from around bridge abutments or piers. Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure.
As well as who should be held responsible for the roof collapse. The firm of Lev Zetlin Associates was hire to do an investigation of what caused the roof to collapse. The firm’s results were that the exterior top chord compression members on the east and west faces were overloaded by as much as 852%, the exterior top chord compression members on the south and north faces were overloaded by as much as 213%, the interior top chord compression members in the east–west direction were overloaded by as much as 72%. In short the designs were not close to what was originally designed. There were other differences in the weight of the frame.
Bridge efficiency is important as it helps reduce cost of building while maximizing the strength of the bridge. Many things can influence the bridge’s strength and weight, but the two main things that can cause a bridge to be a failure or success is the design of the bridge and construction of its joints. In order to build a potent balsa truss bridge, it is crucial to know how the layout of members and style of gluing can help increase or decrease strength.
For this bridge its fall was inflicted by an unknown patron. One who’s identity or existence we never see verified. The record of the fall is short in the story described as only being for a moment. Then the bridge was finally introduced to “the sharp rocks which had always gazed up at me so peacefully from the rushing water”. Rocks gazing peacefully? This is almost as absurd as a bridge turning around. An action that the bridge itself cannot seem to believe it is doing. This attempt by the bridge was his final effort before his fall. I cannot even picture how a bridge would turn around and attempt to look on his back. The question that comes to my mind is how can a bridge see what’s on his back? If this book is trying to make us believe that this bridge is a human, or has human like qualities. Then how flexible a person is this bridge? Because I know very few people who can see whats on their back. Especially without turning so much that anything on their back would fall off. So is this bridge so inflexible that it breaks itself by turning around or is it trying to buck off its attacker unintentionally? This answer is never answered due to the story ending shortly thereafter this scene. With the short fall of the bridge onto the sharp rocks it had stared at for the entirety of its life. The events before and during the fall of the bridge was the main issue I had with my thesis that the bridge was