Balsa Wood Bridges
Nidhi Shah
GSMST
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.
Truss bridges can be built three different ways—as a pony bridge, through bridge, or deck bridge. A pony bridge, or a bridge in which the bracing is only on the sides and on top of the deck, are most often used when having a lighter load as there
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There are two main things that can be used to secure joints: balsa cement or cyanoacrylate glue. Before gluing two pieces together, lay them out on a work board or wax paper and use pins to prevent the members from moving apart; the pins should not be placed near the joints so that it is easier while gluing (Anderson 2006). Then, apply the glue to the members and make sure that they touch to create the strongest joint possible. Despite it seeming as if more glue would make a structure stronger, using bulks of glue can cause the bridge to fail as cyanoacrylate bulk will cause the joint to become more brittle (Anderson 2006). To prevent excess gluing with cyanoacrylate, a special glue applicator should be used to minimize the amount of glue added to the wood, and to increase strength with balsa cement, thin the glue out first by making the solution 30% water. This process will be utilized when constructing the bridge to ensure that the joints are sturdy enough to withstand weight and won’t be the cause of failure. Based on the research conducted, the bridge being built will be a Pratt or Parker Bridge with a height of about 2.5 inches. Members will connect to one another through lap joints, and when a lap joint cannot be used, an end joint with two gussets securing it in place will be used. Gorilla Glue and Alteco ST50 Super Glue will be used to connect members at these joints. The glue will be applied to balsa members pinned to a workspace through a glue applicator to assist in applying a precise amount of
Have you ever thought about driving over a suspension bridge held up by cables? That’s what the Mackinac Bridge is. With the building of the Mackinac Bridge there has been many positive effects that have come out of it.
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 Jericho Covered Bridge in Kingsville, Maryland was built in 1865 and restored in 1982. The bridge is 100 feet long and cased in cedar planks and timber beams. Legend has it that after the Civil War many lynchings occurred on the bridge. Passersby were supposedly captured on the bridge and hung from the upper rafters. The bridge is very close to my house and I have driven over it several times. The storyteller, age 19, also lives a couple minutes away from the bridge. He has lived in Kingsville, Maryland his entire life. He recalled a dramatic story he had heard from his older brother involving the haunted bridge.
The Bailey Island Bridge is located in Harpswell, Maine on Route 24. Before the making of the bridge, the fishermen that lived on Bailey’s Island wanted a bridge that connected their island to Orr’s Island. The town of Harpsweell made and voted on their decisions in the weekly town meetings (“Bailey”). The project was stalled because of some of the mainlanders in the town, but it was brought back up for discussion in 1912. They first agreed on a “road” which would connect the two islands and would be constructed with timber. This was to cost $3,000. The cost quickly reached $25,000 at a later town meting because they decided to build the bridge with stone and concrete instead. Once the legislature decided to pass a bill stating that it would fun state’s highway and bridge projects, they decided to move forward with the project (Hansen, 36).
The 1.78 mile western span of the bridge between San Francisco and Yerba Buena Island presented the first obstacle. The bay was up to 100 feet deep in some places and required a new foundation-laying technique. Engineers developed a type of foundation called a pneumatic caisson to support the western section. A series of concrete cylinders were grouped together and then capped-off, having the air pressure of each cylinder identical to balance the beginning of the structure. From there, the workers added sets of new cylinders until the caisson reached the bottom of the bay. Then, in order to reach the bedrock, they inserted long drills down the cylinders, digging until they reached bedrock. After the caisson was balanced at the bottom of the bay, workers filled it with 1 million cubic yards of concrete, more concrete than was used for the construction of the Empire State Building! This caisson connected the two suspension bridges that make up the western part of the bridge.
BRONX- 25 year old man is found dead after driving off the Bronx Neck Bridge with his girlfriend in the trunk of his car at around 2:00am.
Following the collapse of the I-35 Bridge, other bridges in the country, with similar construction designs, were scrutinized. According to federal statistics, more than 70,000 of the 607,363 or roughly 12 percent of the bridges in the United States are classified as “structurally deficient.”
The book The Bridge on the Drina written by Ivo Andric is a very fascinating novel of religious, folk tale and executions that describe how political issues and religious ethnics caused a big debate in the town of Visegard. The bridge is built for the people inhabited within the junction of the Drina River and Rzar River where it creates a triangular land scenery. It eventually connects Sarajevo and Stambul together. The bridge at first is described as bringing hell to the people who live along the area until they see the beauty that the bridge creates for the area and for the people who use it daily in their lives.
Since humans are mortal, the sensation of pain is integral to the human condition. On one hand, pain alerts the body of a danger that is threatening its overall well-being; however, pain can be used as a means of torture to break the psyche or willpower of someone. As Lancelot races to save his queen from the evil Méléagant, he encounters the Sword Bridge. This Bridge is notorious for its slender construction, making it impossible for one
People who thinks of Thornton Wilder primarily in terms of his classic novella “Our Town,” The Bridge of San Luis Rey will seem like quite a switch. For one thing, he has switched countries; instead of middle America, he deals here with Peru. He has switched eras, moving from the twentieth century back to the eighteenth. He has also dealt with a much broader society than he did in “Our Town,” representing the lower classes and the aristocracy with equal ease. But despite these differences, his theme is much the same; life is short, our expectations can be snuffed out with the snap of a finger, and in the end all that remains of us is those we have loved.
One of the great engineering feats when building this bridge was the use of steel. Despite its maximum height of 343m span of 2.46km, 280m above the valley floor, the bridge is actually quite light. 242,000 tonnes seems like a lot but without the use of steel on the structure, this bridge would have been more than twice as heavy. Steel is a much stronger material than concrete, so can support more weight with less mass. The actual road deck, which is comprised almost entirely of steel, only weighs 36,000 tonnes. The other 206,000 tonnes comes primarily from the massive pylons, which are m...
There are two theories (T1: Theory One) and (T2: Theory Two) that have different implications for how to build a bridge. These two theories are similar because they both have not been falsified however they differ because one has been tested and the other has not. The theories are stated explicitly below.
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.)
However, before doing this we had to look more into depth on the materials we will use to construct our bridge. We also have to consider the possible environmental and geological factors that should be taken into consideration for our model. Pertaining to environmental and geological factors, there are many stipulations that structural engineers take into consideration before the construction of a truss bridge begins. The main objective of the geotechnical engineers are to protect the lives of others and avoid property damage from happening which can be caused by various geological conditions. Geological engineering uses principles of soil and rock mechanics to find surface conditions and materials.The Geotechnical engineers complete works such as: geological hazard assessments, material properties, landslide and slope stability, erosion, flooding, dewatering, and seismic investigations. These engineers closely examine all of these important factors before constructing a bridge in a certain location. According to Teach Engineering.com, constructing a safe and efficient bridge requires an ample amount of time and energy. Environmental and geological factors play a major role in construction, as
The Golden Gate Bridge is a major tourist attraction in San Francisco, California. It is one of the longest suspension bridges in the world and it’s also the top suicide location in the world.The Golden Gate Bridge is a symbol of Northern California. The bridge serves as a means of transportation.