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36
Of all the frightening things of the world none is so frightful as an earthquake. No
place on earth may be safe from the possibility of such a disaster. More than 1,000 quakes
occur each year around the globe. Sudden, abrupt and powerful shifts of the earth’s crust
result in vertical up to 7m and horizontal up to 4m displacements. Because of such dis-
placements the spans of the bridge can be thrown off the supports, besides the piers them-
selves can be damaged and move into an inclined position or even displaced.
Hurricane can also result in the bridge collapse although at present the building
codes take into consideration the forces of the most powerful winds and calculate them
with great precision. In 1879 the bridge having five spans 75m long was thrown off the
piers on Lake Tay in Great Britain. The train moving along the bridge at that moment
added an extra force for the impact of the wind speed (about 140 kmh). In 1904 the via-
duct supports 90m high were overthrown and the 76m long spans fell down under the
wind blowing at 280 kmh in St. Paul, U.S.
Ice impact is rather dangerous for the bridgeworks as well. In 1938 the ice jam
1
which was more than 27m thick and 120m long cut the abutment of the arch span 256m
long on the Niagara River, U.S. The bridge has been in service for forty years and the ice
level twice reached the danger point during its service life. The last ice jam was building
up during 36 hours but nothing was done to blast it off.
Natural disasters are not the only reason causing failures and collapses of construc-
tional works. Rather often people’s knowledge about the physical and other properties of
construction materials may be not sufficient to build a strong and stable bridge. Thus, the
lack of the knowledge about the metal behavior led to the bridge collapse in Belgium in
1938. When the air temperature dropped abruptly to the low subzero points some of the
metal elements of the arch span burst even without any additional loads. This metal condi-
tion is called brittleness or shortness of steel. It is caused by the carbon content of steel.
Note: 1) ice jam – затор льда.
Ex. 8. Search the text for the English equivalents of the following Russian
phrases:
вызывать разрушение, сдвиг земной коры, смещение, строительные нормы,
с большой точностью, влияние (воздействие) силы ветра, находиться в эксплуата-
ции, физические свойства, поведение металла, содержание углерода.
Ex. 9. Go back to the text, guess the meaning of the following phrases and
translate them into Russian:
engineering and technical calculations, operational and structural safety, around the
globe, a strong and stable bridge, to drop to the subzero points, additional loads.
Ex. 10. Translate the following questions into English and answer them. Do
it in written form.
1. Чем обычно
вызываются обрушения мостов? 2. Вы согласны с тем, что зем-
летрясения могут происходить в любом месте земного шара? 3. Почему землетрясе-
ния опасны для искусственных сооружений? 4. Может ли затор льда стать причиной
обрушения моста? 5. Какие стихийные бедствия могут стать причиной аварий и раз-
рушений? 6. Какого содержание углерода в стали? 7. Какие свойства металла
необ-
ходимо принимать во внимание при (when) строительстве моста или какого-либо
другого искусственного сооружения?
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