Friday, March 28, 2008



On November 7, 1940 the Tacoma Narrows Bridge was hit by winds of up to 40mph. The bridge began to twist and flutter. Some cables snapped and a six-hundred foot section of the bridge fell into Puget Sound. ^Wind is but one disaster, earthquakes are another^ (Jay Stuller 36). Disasters like this one and others could have been avoided if the proper precautions had been taken. Due to the disasters in the world the structures of today and tomorrow are much safer. Today most of these catastrophes are avoided because of the up to date technology, like architecture, predicting the disasters before hand and new techniques used by emergency rescue teams. Some major advances in today^s buildings include such things like the material used. For instance products like steel-reinforced concrete (refer to diagram 3-1), steel framing, and properly braced wood frames for houses are a few examples of how buildings are being retrofitted and new buildings are being built towards protection from disasters. As well, the foundations of the buildings can be built on shock absorbing ^base isolators^ containing springs or alternating layers of steel plates and rubber, to counteract the effects of earthquakes.

In Japan architectures have been keeping mind earthquakes while designing and building structures. Unfortunately the buildings were mainly designed to withstand a vertical force. The Japanese buildings were designed to withstand a certain acceleration force, but in January 1995, an earthquake hit the city Kobe devastating the buildings, which were thought to be safe. It just shows, ^that building design criteria are crucial to withstanding effects of earthquakes^ (Gerad Baker 12). The normal Japanese wooden houses that had heavy roofs collapsed, and also newer homes were demolished, as seen on diagram 3-2. This could have been avoided by building the houses with lighter plywood frames with crossbars that distribute force evenly rather than houses with heavy timber walls that collapse under force. As well the materials used to build the structures has a great deal to do with the survival rate of buildings. The use of reinforced concrete is thought to be a major reason why buildings stay intact. It is possible to reinforce older buildings with extra concrete simply and effectively, which has been done in California since 1989. Bridges, a totally different aspect of building, but a very similar method for creating sound structures. During the Kobe earthquake the Hanshin expressway collapsed on its side for a stretch of 600m (pictures seen on page 5). This type of roadway is built upon reinforced concrete pillars. There is steel inside the pillars to increase its ability to bend and flex with the quake. But unfortunately, this creates new problems; shaking the road from side to side, the concrete crumbles because it is confined and under a great force, the concrete will split and give way. To deal with these problems builders can fit metal jackets to limit any extra force by containment, inserting steel spirals or fitting steel rings, where force is taken into the steel. Another famous bridge, the Golden Gate Bridge, in San Francisco went under a $147 million earthquake-proofing retrofit after the 1989 Loma Prieta earthquake. The main parts reconstructed were to the towers, supporting piers and the approaches to the bridge. The Bridge was reinforced at the anchorage housings, and fit with vibration-dampening additions over the south bridge. While the north viaduct gets ^isolators^, to stop ground movement and shake entire structure.

The Beaches of the world all seem to be receding. In the United States about 900f the coast is eroding. The reason for this is because of constant storms and the removal of natural buffers (sand dunes) by humans to build hotels and homes. Although the sand is replaced constantly, ^most comes back, you don^t get back all you lost^ (Betty Nash). There are several thoughts on how to stop or reduce erosion damage that includes both hard and soft structures. The hard concrete structures should be placed parallel or perpendicular to the shore to confine the sand to a certain area. But haplessly, this solution can create more problems because although it may protect one area it can accelerate erosion in adjacent areas. The soft idea is to ^nourish^ the beaches with similar sand. Now although, the method can work it can be very costly. The decision is up to the owners of the beach, whether or not the cost damage is greater than the cost of keeping it nourished. In Virginia Bea! ch it saved an estimated $12. 5 million (1993 U.S. dollars) in damages. So in spite of the fact that technology has advanced it is still not equal to the power of Mother Nature. Humans have been able to counteract some damages with new ideas like reinforced concrete, building designs, safety measures, and use of previous disaster information to reduce the risk of human causalities. For the rest of time Man will battle nature, one always trying to top the other.



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