1、 外文翻译 指导教师： 赵同峰 专业班级：土木 07 3 班 学 号： 0702090306 姓 名： 王巍 沈阳建筑大学 土木工程学院 英文资料 The October 17, 1989 Loma Prieta Earthquake October 1989 Commercial Structures The Loma Prieta Earthquake and its subsequent aftershocks resulted in widespread damage to a variety of commercial structures. A large geographical
2、 area was affected, as is typical for an earthquake of this magnitude. The affected area encompasses eight counties, from Monterey and San Benito in the south to San Francisco, Alameda, and Contra Costa in the north. In total, building structures experienced damage over an area of approximately 3,00
3、0 square miles. Although damage was widespread, it was also quite sporadic. As would be expected, areas closest to the epicenter including Hollister, Los Gatos, Santa Cruz, and Watsonville experienced the most concentrated damage. Farther away, heavy damage was generally limited to buildings of very
4、 poor construction founded on soft soils that failed or amplified the earthquake ground motions. This is similar to the effects noted in the 1985 Mexico City Earthquake. Earthquake effects also tended to be highly directional. Most damage occurred within a narrow band that extends northwest to south
5、east, approximately paralleling the San Andreas Fault. Thus many communities along the margins of San Francisco Bay escaped serious damage. Unreinforced Masonry Buildings As has been observed in past California earthquakes, the most concentrated and severe damage to building structures occurred in u
6、nreinforced masonry (URM) bearing-wall buildings. URM buildings, constructed of wood-frame roof and floor systems supported by thick unreinforced brick walls, were commonly constructed throughout California until the 1930s, when the adoption of building codes with seismic-resistive provisions preven
7、ted their further development. As a result, URM buildings are typically found in the central business districts of older California cities Failures of URM buildings result from inadequate anchorage of the masonry walls to roof and floor diaphragms, as well as the limited strength and ductility of th
8、e basic building materials and poor construction workmanship. Deterioration of the sand-lime mortar and wood framing due to weather exposure frequently contributes to poor performance. California has recently enacted legislation (SB 547) requiring cities to identify URM buildings and develop plans t
9、o reduce the risk they present. Damage to URM buildings in the Loma Prieta Earthquake ranged from dramatic collapses near the epicenter to fallen parapets in Martinez, more than 70 miles away. Life-threatening collapses also occurred in Hollister, Los Gatos, Oakland, and the San Francisco financial
10、district. The roofs and floors in many buildings with collapsed walls seemingly defied gravity by continuing to stand after losing their load-bearing support. Generally, buildings with through-wall anchorage to floor and roof framing performed better than buildings without this feature. Most URM bui
11、ldings in the region survived the earthquake without collapse or obvious substantial damage. However, field investigations show that many of these structures have experienced extensive cracking of the masonry and are therefore weakened. If not repaired, some of these buildings are likely to collapse
12、 in future earthquakes. URM buildings with more than three or four stories were generally constructed with steel frames to carry the gravity loads. Masonry walls in these buildings were primarily provided for building closure and partitions and to add lateral shear-resistance to the structure. These
13、 steel-frame infill masonry buildings have generally performed better in past California earthquakes than the smaller bearing-wall buildings. Nonetheless, these buildings were included in California legislation addressing the unreinforced masonry hazard. In the Loma Prieta Earthquake, many steel-frame buildings with infill masonry
