Bridge Analysis Essay

The report debates the Tacoma narrows bridge failure and the different theories of how it came about, using information about what type of bridge it is and the forces acting on it before and during the collapse. It also discusses ways in which the failure could have been avoided, from changes in the design to modifications to the bridge after its construction.

Calculations were performed to determine the effectiveness of the design of the platform. Allowing for a safety factor of 1.5 times the design weight of 10kg and considering the bridge must not be overdesigned; plans were made for the bridge to fail at 25kg, 2.5 times that of the design weight. According to the calculations, the bridge would hold a load of over 15kg and experience failure at 20kg in the members. These calculations were later disproven in the testing, breaking 8kg earlier than expected, due to unforseen errors. An analysis of the bridge design and calculations has been included at the end of this report.

The I-35W Mississippi river bridge also known as Bridge 9340 officially was an eight-lane, steel truss arch bridge which carried the Interstate 35W across the Mississippi river connected the downtown east and Marcy-Holmes. Its construction began in the year 1964, was finally opened in 1967. It connected the northeast of Metrodome on its south end and the University of Minnesota on the North end. The bridge was the boundary of “Mississippi Mile” downtown riverfront parkland. The north foundation of the bridge was near the hydroelectric plant built in 1988. The south abutment was in an area polluted by the coal gas processing plant. There weren’t any mentions of this in the failure investigations. The bridge was a continuous truss bridge that had a total span of 1,907 ft. It was an 8-lane bridge having a width of 113.3ft. and was 115 ft. high. It was designed by Sverdrup & Parcel to 1961 AASHO (American Association Of State Highway Officials) standard specifications. The construction contract worth more than US $5.2 million at the time, went to Hurcon Inc. and Industrial Construction Company, which built the steel trusses and deck. The piers were not built in the navigation channel instead the center span of the bridge consisted of a single 456- foot steel truss over a 390-foot channel being the longest span of the bridge.

The Tex Wash Bridge was built in 1967, listed as functionally obsolete in 2014, and failed do to collapsing in July of 2015. After 2014 inspections were made and no flaws were detected so it was left unchanged. In 1967, the construction crew had the task of spanning the Tex Wash to connect the freeway between California and Arizona along the Chuckwalla Mountains. They decided the best, and most cost effective, way of doing this is by channeling a dry riverbed and narrowing it where the bridge was to stand. The columns of the bridge were to stand on their foundations which was sitting on the soil and the banks of the bridges were given large rocks to protect their foundation from being washed away (Kelman).

There are many differences between our bridge and other bridges. One being location. Another one being that thing that was sacrificed for it. Another one being cost. Also another difference would be weight and capacity, and the size or length.

Several students are doing Science Fair projects at Woodstock Middle School and I am one of the seventh grade students. The topic I shall be doing is on how bridge structure affects the weight bearing capacity. I chose this specific topic to guide bridge builders in the right direction on what bridge is safest for public use. The key topics I plan to research on include the following: Beam, Warren Truss, suspension, cable-stayed, and arch bridges. I shall use the scientific method to guide me through this process.

The design error along with a few other factors led to the collapse of the bridge. When the bridge first opened, the traffic deck had 2 lanes of traffic going in each direction for a total of 4 lanes. However, in 1998, the bridge was renovated so that there were 4 lanes of traffic going in each direction for a total of 8 lanes. Along with a few other bridge renovations, the weight of the bridge was significantly increased. Also, the rush hour traffic and the construction vehicles located on the bridge for repairs during the day of collapse added a considerable amount of weight too.

According to Hecox (2011), the Tillman Bridge is 1900 ft long; also, it is 900 ft above Colorado River and has the world's tallest precast concrete columns. Its central span has 1060 ft, which is the longest single-span concrete arch of the western hemisphere. On the other hand, the St. Anthony Bridge has, according to Jones (2015), only 559 ft of lenght; which is about four times smaller than the Tillman Bridge. St. Anthony’s central span has only 305 ft, which is also very small when compared to the 1060 ft of Tillman Bridge. Another difference between the two bridges is that St. Anthony doesn’t have high elevations like the Tillman. In addition, both bridges are top-down constructed; the first one innovated using this method of construction because its elevated heights (Hecox, 2011). The second used this method because of the non-stop traffic under the bridge, and the necessity to remove the older one while building the new. However, the old bridge will not be totally discarted. A portion of the previous bridge will be used in a new interpretive plaza at the west end of the new bridge. In conclusion, both bridges have unique design features that make them very important to their

In 1989, an earthquake caused the top deck of the bridge to collapse. This has raised concern in recent years in the case of a large scale earthquake. During an inspection in September of 2009, a 1.5 inch crack was found in a structural truss called an eyebar. The system of the truss is meant to distribute report will describe the tensile load from the weight of the bridge over 4 eyebars. One of them being broken, this same load was now distributed between only 3 eyebars. Because these eyebars were not designed to carry extra load, it became crucially important to repair the eyebar as soon as possible. However, because the bridge is so old, its mechanisms were more complex than what would be designed now in the current day. The engineering company C.C. Myers was contracted to do the repair. C.C Myers decided to repair the eyebar by welding a crossbar to the saddles which had been placed on each end of the broken eyebar (Alfrey, 2010). Four tie rods were then bolted to distribute the tensile load (Reid, 2010). This repair was completed in only 70 hours (Carlsen,

The Interstate 35W bridge otherwise known as bridge 9340 is one of the busiest bridges in Minnesota (Karnowski). On average about 140,000 vehicles cross the bridge everyday (Weeks). The truss bridge was built back in the 1960s (Karnowski). It runs through downtown Minnesota across the Mississippi River. There are four lanes in each direction and it’s 1,907 feet long and 113 feet wide (Weeks).

When the bridge was tested, at 26 pounds of pressure, it began to buckle. The top support near the middle of the bridge on one side caved in, and as the weight increased, more of the top supports collapsed. At 47.3 pounds of pressure, the bridge snapped in half. By the end of the testing, the bridge had lost all of it’s top supports, two sections of diagonal supports on either side, and a small portion of the roadway.

As it aged into the twenty-first century, Washington State Route 520’s Evergreen Point Floating Bridge began experiencing significant problems that indicated it was approaching the end of its useful lifespan. Government agencies big and small came together to bring forth a replacement bridge project to improve the safety and quality of transportation infrastructure to and from the City of Seattle for many years to come. Over a five-year span, construction was performed to create a floating pontoon bridge, similar in style to the original, but wider and better equipped to withstand the natural conditions of Lake Washington and the Puget Sound region.

This report mainly presents causes and consequences that resulted in the structural failure of the I-35W Mississippi River bridge which was constructed since 1964 and the further implication for me. It was found that the bridge collapsed due to undersized gusset plates, inefficient maintenance project and overloaded equipments. As a result of the abrupt collapse that brought about 13 dead and 145 injurers, the state government carried out a series of effective rescue, forced the designing company to pay the price and exerted themselves to eliminate pressures imposed on both traffic and business. It can be concluded that qualified engineers are required to be both ware of social responsibilities of engineers and adept at the professional skills that they specialised respectively.

Recognizing the aging national infrastructure, Intermodal Surface Transportation Efficiency Act in 1991 mandated bridge management systems (BMS) as a part of all state department of transportations

Because of advancements in today’s technology in construction field, many types of bridges are being constructed depending on the requirement and their suitability for the situations.