土木工程外文翻譯2

1、<p><b>　　外文翻譯</b></p><p>　　指導教師： 趙同峰</p><p>　　專業(yè)班級：土木07—3班</p><p>　　學 號：0702090306</p><p><b>　　姓 名：王巍</b></p><p>　　沈陽建

2、筑大學 土木工程學院</p><p><b>　　英文資料</b></p><p>　　The October 17, 1989 Loma Prieta Earthquake</p><p>　　October 1989 </p><p>　　Commercial Structures</p><p&

3、gt;　　The Loma Prieta Earthquake and its subsequent aftershocks resulted in widespread damage to a variety of commercial structures. A large geographical area was affected, as is typical for an earthquake of this magnitud

4、e. 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 approx

5、imately 3,000 square miles.</p><p>　　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 Watsonvil

6、le experienced the most concentrated damage. Farther away, heavy damage was generally limited to buildings of very poor construction founded on soft soils that failed or amplified the earthquake ground motions. This is s

7、imilar to the effects noted in the 1985 Mexico City Earthquake.</p><p>　　Earthquake effects also tended to be highly directional. Most damage occurred within a narrow band that extends northwest to southeast

8、, approximately paralleling the San Andreas Fault. Thus many communities along the margins of San Francisco Bay escaped serious damage.</p><p>　　Unreinforced Masonry Buildings</p><p>　　As has be

9、en observed in past California earthquakes, the most concentrated and severe damage to building structures occurred in unreinforced masonry (URM) bearing-wall buildings. URM buildings, constructed of wood-frame roof and

10、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 prevented their further de

11、velopment. As a result, URM buildings are typically</p><p>　　Failures of URM buildings result from inadequate anchorage of the masonry walls to roof and floor diaphragms, as well as the limited strength and

12、ductility of the 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 recen

13、tly enacted legislation (SB 547) requiring cities to identify URM buildings and develop plans to reduce the risk they present.</p><p>　　Damage to URM buildings in the Loma Prieta Earthquake ranged from drama

14、tic 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 district. The roofs and

15、 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 framin</p>

16、<p>　　Most URM buildings 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

17、 the masonry and are therefore weakened. If not repaired, some of these buildings are likely to collapse in future earthquakes.</p><p>　　URM buildings with more than three or four stories were generally cons

18、tructed 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 steel-frame i

19、nfill 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 th</p>

20、<p>　　In the Loma Prieta Earthquake, many steel-frame buildings with infill masonry walls performed quite poorly, although no collapses occurred. Several major structures of this type in San Francisco and Oakland

21、experienced extensive damage including partial loss of the exterior masonry walls, shattering of interior clay tile partitions, and cracking and spalling of terra-cotta veneers.</p><p>　　Concrete Buildings&l

22、t;/p><p>　　Many older reinforced concrete structures have very limited seismic resistance. These buildings tend to be quite heavy, resulting in large seismic forces. In addition, concrete itself is quite brittl

23、e and requires extensive amounts of reinforcing steel to perform properly in earthquakes. Most concrete structures designed prior to the mid-1970s do not have adequate reinforcing steel to ensure good performance. Termed

24、 non-ductile concrete structures by engineers, these structures have collapsed in</p><p>　　Fortunately, there are relatively few non-ductile concrete buildings in the region and no buildings of this type col

25、lapsed. Many mid-rise concrete structures did experience extensive damage, however. Damage typically consisted of large diagonal cracking of shear walls, occasionally accompanied by spalling of large pieces of concrete f

26、rom the building</p><p>　　A fifteen-story concrete shear-wall structure in downtown Oakland was extensively damaged. The lightweight concrete shear walls at the first story literally shattered, exposing the

27、reinforcing steel to view. The presence of a redundant steel frame within the building may have prevented the collapse of this structure.</p><p>　　A six-story concrete shear-wall building in San Francisco al

28、so experienced substantial damage. This building had recently been seismically strengthened with the addition of steel braces on the building perimeter. Due to poor design and construction workmanship, the attachment of

29、the braces to the building was inadequate and most of the bolts failed. Building deflections following failure of the bracing caused an interior column to punch through a floor slab. Extensive damage to shear walls above

30、</p><p>　　Tilt-up Buildings</p><p>　　Concrete tilt-up buildings are the most common form of modern low-rise industrial and commercial construction throughout California. They usually are constru

31、cted with plywood sheathed wood-frame roofs supported by perimeter concrete walls. They are called tilt-ups because the perimeter walls are constructed lying flat against the floor slab and then tilted-up into position a

32、round the building. Extensive damage to these buildings has been observed in past earthquakes, including the 1987 Whittier </p><p>　　Thousands of tilt-up buildings are present in the affected region. Althoug

33、h some significant damage was experienced near the epicenter, the greatest concentrations of these buildings are located in areas that experienced very weak ground motion. Most of these buildings therefore had little dam

34、age.</p><p>　　Several buildings in Hollister were investigated. Several tilt-up building partially collapsed as the result of inventories of stacked cans containing tomato product impacting the walls during

35、the earthquake. Damage was extensive. Much of the inventory was lost or severely damaged. This underscores the importance of addressing seismic issues relating to equipment and contents, as well as structural designThe b

36、uildings appeared to be late 1960s or early 1970s vintage and as such were observed not</p><p>　　In Watsonville, several panels of a large tilt-up owned by a food packager bowed outward at mid-height and app

37、roached collapse. Concrete spalled off of several of the pilasters in the building wall, exposing the reinforcing steel, some of which buckled. In another, newly constructed Watsonville tilt-up, interpanel connections at

38、 a skewed corner were damaged and roof sheathing was severely torn.</p><p>　　Steel Buildings</p><p>　　Modern steel-frame buildings performed excellently in this earthquake, as they have in the p

39、ast. Damage to these structures was typically limited to cracking of cladding and interior partitions and widespread disarray of contents. The nonstructural damage sustained by steel-frame buildings may largely be attrib

40、uted to their flexibility, which results in very large displacements.</p><p>　　A steel-frame building with corrugated metal siding in Hollister serves as a warehouse for a food company. As with the concrete

41、tilt-up buildings in Hollister, this tomato packing company experienced severe damage to its steel-frame building and significant loss of inventory. Canned tomato products stacked over 30 feet high on standard pallets we

42、re mobilized by the earthquake. Most stacks collapsed, impacting and ripping through the corrugated metal side walls. </p><p>　　Impact forces were so great that several tapered steel columns and beams were s

43、everely damaged. These steel members twisted, bent, and failed, taking down an entire section of the building. Much of the inventory was lost or severely damaged. As with concrete tilt-up warehouses, this incident highli

44、ghts the effect that stored inventory can have on the integrity of a building during an earthquake.</p><p><b>　　Summary</b></p><p>　　The remote epicentral location of this earthquake

45、 allowed the San Francisco Bay Area to survive with relatively few instances of structural collapse. Except for buildings near the epicenter, most cases of severe damage occurred in older buildings with little seismic ca

46、pacity and in areas of extremely weak soils. The fact that many inadequate structures in the region experienced little damage indicates that ground motion in most areas was not severe. Even so, most businesses experience

47、d at least </p><p>　　Residential Structures</p><p>　　Most residential buildings in the affected area are of wood-frame construction. Such buildings have generally performed well in past earthqua

48、kes because they tend to be light, minimizing inertial forces; and because they are relatively rigid, minimizing damage associated with deformation, such as cracking of interior walls. There are, however, major exception

49、s to this generally good performance record. </p><p>　　Older (especially pre-1940s) homes, because they lack positive connections to their foundations or have raised floors supported by relatively weak cripp

50、le walls.</p><p>　　Some of the more irregularly shaped newer homes, because they lack clear load paths due to complex geometry or are built without enough wall area to resist the seismic forces.</p>&

51、lt;p>　　Multi-story apartment buildings or houses with garages on the ground floor, where garage doors have replaced most solid walls.</p><p>　　Except for areas of poor soils (soft, saturated sands and sil

52、ts), which experienced severe damage as far away as San Francisco, damage to residences was generally limited to the epicentral area of Watsonville, Santa Cruz, and Los Gatos.</p><p>　　Epicentral Area</p&

53、gt;<p>　　Residential building damage in the epicentral area was widespread and considerable, although most newer houses performed very well. Many buildings with wood-lath-and-plaster walls suffered severe interior

54、 nonstructural damage; damage to gypsum board interior walls appeared to be significantly less severe. Chimney damage ranging from cracking to twisting and collapse was observed throughout the epicentral area. Such damag

55、e was observed in as many as 30% to 40% of the homes in the older areas of W</p><p>　　Severe structural damage to homes observed could mainly be attributed to failure of unbraced cripple walls and lack of si

56、ll anchorage. These cripple walls are short wood stud framing present between the foundation and first floor of the building. Because they are not sheathed with plaster, as are walls in the living area, they are substant

57、ially weaker and a common location for failures.</p><p>　　Such damage was mainly observed in pre-1940s homes with horizontal wood sheathing. These homes moved laterally from several inches to a foot, until t

58、he cripple walls became unstable and collapsed. Damage to utility lines due to this motion was frequent. In Watsonville, cripple wall failures were observed in approximately 10% to 20% of the pre-1940s residences through

59、out the area, with many blocks suffering close to 100% failures. In Santa Cruz, damage appeared to occur mainly in the area of poor</p><p>　　Severe damage was also apparent on Myrtle Street, near the wastewa

60、ter treatment plant at Neary Lagoon. On one block, five of twenty-five homes had cripple wall failures. On this street, correlation of damage with quality of maintenance and general pre-earthquake condition was evident.

61、Apparently, older homes that had been restored architecturally often also had structural upgrades. The table on the following page shows none of the homes with "good" pre-earthquake condition to be severely dam

62、aged</p><p>　　San Francisco Marina District</p><p>　　The most severely damaged area in San Francisco was the Marina district. The soils in this area consist mainly of soft, saturated sands and s

63、ilts, some of which are naturally occurring, but most of which were filled-in for the Panama-Pacific Exposition circa 1915.</p><p>　　Most of the buildings in the Marina district are apartment buildings and s

64、ingle-family houses of wood-frame construction, two to five stories high, built in the 1920s. Most of these buildings are constructed with parking garages at the first story. A large percentage of the buildings in the Ma

65、rina district suffered damage. Although plaster and stucco cracking was evident in all buildings in the Marina district, the most severe damage was observed in mid-rise (four- to five-story) apartment build</p>&l

66、t;p>　　Failure of these buildings was due to two main effects. First, the mass and stiffness of the buildings may have produced fundamental periods of vibration close to the predominant period of vibration that was amp

67、lified by the soft soils in the area. Second, it appeared that nearly all of the collapsed and partially collapsed buildings had the same configuration: these buildings all had numerous garage door openings at the first

68、level, resulting in a lack of story shear strength or a "soft story."</p><p>　　Seismic settlement and liquefaction caused severe cracking and buckling of streets and sidewalks in the Marina distric

69、t. Soil failures did not appear to be a direct cause of building collapses; however, they undoubtedly contributed to the overall problem</p><p>　　Seismicity and Geology </p><p>　　The epicenter o

70、f the Richter magnitude 7.1 earthquake was located about 10 miles northeast of Santa Cruz along a segment of the San Andreas Fault, near Loma Prieta in the Santa Cruz Mountains. The focal depth has been placed at 11 mile

71、s. This is unusually deep, as typical California earthquake focal depths are 4 to 6 miles. </p><p>　　A magnitude 5.2 aftershock occurred approximately 2.5 minutes after the main shock, and thousands of after

72、shocks have been recorded since. In the week following the earthquake, a total of 300 of these have been magnitude 2.5 or greater and 20 have been greater than 4.0. </p><p>　　The aftershock zone stretches ac

73、ross 25 miles from just north of Los Gatos near Highway 17, to south of Watsonville near Highway 101. This zone corresponds with the areas of greatest damage. The zone ranges from about 2 to 11 miles in depth and is beli

74、eved to be the length of rupture associated with the main shock. </p><p>　　Surface Effects</p><p>　　Surface displacements with offsets of up to 3 or 4 feet along a zone about 20 miles long would

75、 normally be expected to accompany an earthquake of this magnitude. Instead many cracks have been found over several discontinuous and indistinct zones. There are several possible explanations for this lack of clear surf

76、ace expression. The earthquake was unusually deep, making it difficult for the bedrock rupture to propagate to the ground surface. The combination of rugged topography, thick soil, and f</p><p>　　Historical

77、Seismicity</p><p>　　The San Andreas Fault trends northwesterly and extends more than 800 miles from the Gulf of California to Cape Mendocino north of San Francisco. It has been the source of many large earth

78、quakes including an 1838 earthquake located on the peninsula south of San Francisco (magnitude in excess of 7.0), an 1865 earthquake northeast of Santa Cruz, and the famous 1906 San Francisco Earthquake with magnitude 8.

79、3. </p><p>　　The Loma Prieta Earthquake essentially repeats the 1865 event and is the first major rupture along the San Andreas since 1906. The length of fault rupture generally extended from the southern en

80、d of the 1906 break and thus relieved strain, which had accumulated since before that time. The lack of activity on this section of the fault, as well as the occurrence of several magnitude 5.0+ events in the area over t

81、he last two years, had prompted geologists to forecast this event</p><p>　　The most recent damaging earthquakes in the Santa Cruz area include a magnitude 5.2 earthquake on November 15, 1964, which resulted

82、in broken chimneys; and earthquakes of magnitude 5.3 in June 1988 and 5.4 in August of this year in nearly the same region as the Loma Prieta Earthquake.</p><p>　　The recent rupture is unusual for earthquake

83、s on the San Andreas Fault. Past earthquakes have been the result of horizontal slip of the ground on the two sides of the fault, with the southwest side moving northwest relative to the northeast side. The recent ruptur

84、e of the Loma Prieta Earthquake includes not only this horizontal component of slip, but also a significant thrusting of the southwest side up and over the northeast side. The fault has steep dip to the southwest in this

85、 area.</p><p>　　Ground Motion Records</p><p>　　Strong-motion records were obtained from hundreds of instruments, permitting a detailed understanding of the ground motion throughout the affected

86、region. Preliminary results indicated that peak ground shaking as strong as 0.65g (where g is the acceleration due to gravity) was recorded in both the horizontal and vertical directions in the epicentral area. Relativel

87、y low accelerations were recorded in locations between the epicenter and Oakland and San Francisco; accelerations between 0.20g and 0</p><p><b>　　Soils</b></p><p>　　Surveys of liquef

88、action (a phenomenon in which sand saturated with groundwater temporarily behaves like quicksand when strongly shaken) occurrences revealed that the most heavily impacted sites are in areas of fill along the margins of S

89、an Francisco and Oakland, and along the flood plains of the Pajaro and Salinas Rivers east and south of Santa Cruz. Liquefaction effects were widely noted in the heavily damaged Marina district of San Francisco. The runw

90、ay at Oakland airport, bridges along the Pa</p><p>　　The pattern of damage related to liquefaction and soil consolidation in San Francisco and Oakland is similar to that of 1906. In Oakland in 1906, liquefac

91、tion and settlements caused damage to water mains and wharfs located near what is now the southern end of the collapsed Cypress structure. In San Francisco, previous liquefaction damage occurred near Ft. Mason, close to

92、the location of current damage in the Marina district, and along the Financial district waterfront, where the Embarcadero Free</p><p>　　The earthquake caused thousands of landslides along steep slopes, from

93、hills in the epicentral area to at least as far north as the Pacific Coast just south of San Francisco. Several residential developments in the Santa Cruz Mountains were badly damaged by these slides. On Highway 17 two l

94、anes were blocked west of the summit by a large slide. Large fissures opened in roadways throughout the Bay Area due to settlement and/or lurching.</p><p>　　This rupture of a 30-mile-long segment of the San

95、Andreas Fault has not altered the assessment that there is a 50% chance for one or more magnitude 7.0 earthquakes in the San Francisco Bay Area in the next 30 years. The probability of a repeat of the 1906 magnitude 8.3

96、earthquake is still significant.</p><p><b>　　中文翻譯</b></p><p>　　1989年10月17日,Loma Prieta地震</p><p><b>　　1989年10月</b></p><p><b>　　商業(yè)結構</b&g

97、t;</p><p>　　Loma Prieta地震和它的余震導致了一系列商業(yè)結構的大面積順壞損壞.正如這個量級的典型地震一樣,有一大批地理范圍受到了影響.被波及的地區(qū)包括8個郡,從南部的Monterey和San Benito,到北部的San Francisco, Alameda, 和 Contra Costa .總共有大約3000平方英里面積的建筑結構遭受到了破壞.</p><p>