Why do buildings collapse in earthquakes? Building for safety in seismic areas. Robin Spence

Читать онлайн книгу.

Why do buildings collapse in earthquakes? Building for safety in seismic areas - Robin Spence


Скачать книгу
was carried out by our team in conjunction with University of Peshawar (So 2009) to establish patterns and causes of death and injury. This confirmed that, whatever form of construction was used, the major cause of serious injury and death was structural collapse resulting in entrapment.

      2.2.5 The 27.5.2006 Yogyakarta Earthquake: Mw6.3, 5778 Deaths

      The lack of adequate ties between roof and walls, and the lack of out‐of‐plane strength of the walls were responsible for the collapse of many of the katcha houses. The buildings built using confined masonry generally performed better, though the earthquake exposed many failures in jointing and reinforcing such structures (EERI 2006b).

Photo depicts collapse of house of traditional construction, Yogyakarta earthquake.

      Source: Boen (2016). Reproduced with permission.

      2.2.6 The 12.5.2008 Wenchuan Earthquake: Mw7.9, 87 476 Deaths

      The Mw7.9 Wenchuan earthquake occurred at 14.28 local time on 12 May 2008, with its epicentre in Wenchuan county in Sichuan Province of China, at a depth of 19 km. It caused a fault rupture of around 240 km along faults which form the boundary between the Longman Shen mountains to the north‐east and the Sichuan basin to the south‐west. This is a densely populated region, and the earthquake was devastating to a large area, affecting more than 250 000 km2 and 30 million people (EERI 2008). Peak ground acceleration exceeding 0.5 g was felt over a wide area. The earthquake resulted in approximately 87 500 deaths (including 17 920 missing people), and 375 000 injuries, and required almost 1.5 million people to be relocated. It was the most lethal earthquake to strike China since the Mw7.5 Tangshan earthquake in 1976 which killed an estimated 242 000 people.

      Although most of the deaths were caused by the collapse of buildings, a notable feature of this earthquake was the very large number of slope failures, causing landslides, rock‐falls and mudflows. By one estimate there were more than 15 000 such failures, which resulted in around 20 000 deaths, or nearly 30% of the total (Yin et al. 2009).

      Many of the mixed RC and brick constructions too were seriously damaged, including many ground floor ‘soft‐storey’ collapses. There were some recently constructed RC frame buildings in the larger towns and these were reported to have performed relatively well, and to have resisted collapse in spite of the fact that the ground shaking was much more severe than the levels required by the design codes over most of the area (EEFIT 2008b).

      Particularly noteworthy was the tragic collapse of many school buildings. It has been estimated that more than 7000 school classrooms collapsed in the earthquake, and, as children were in school at the time of the earthquake (14.28 local time), that possibly more than 10 000 children died as a result. Often, collapsed school structures were sited next to other relatively undamaged buildings. This led to angry protests by bereaved families, whose only child was often the victim. Protesters blamed both shoddy construction and the government which should have supervised such construction more effectively. Official investigations took place and are said to have identified many design defects, and there have been subsequent changes to the required standards for school construction (Wong 2008).

Photo depicts partially collapsed five-storey masonry middle school building in YingXiu in the Wenchuan earthquake.

      Source: EEFIT. Reproduced with permission.

      2.2.7 The 12.1.2010 Haiti Earthquake: Mw7.0, Estimated More Than 222 000 Deaths

      The Mw7.0 earthquake which struck the Republic of Haiti at 16.53 local time on 12 January 2010 was one of the most destructive in history. It had its epicentre 25 km from the capital city of Port‐au‐Prince, at a depth of 13 km, and very strong to severe ground shaking was felt throughout the city, which had a population of 3 million, and the surrounding region, resulting in collapse or critical damage to more than 300 000 homes. In addition, the Government of Haiti estimated that 60% of the nation's administrative and economic infrastructure was lost, and 80% of the schools and 50% of the hospitals were destroyed or damaged. The death toll was initially given by the Haiti Government as 316 000 (DesRoches et al. 2011) but an estimate of around 220 000 is now widely accepted, although other estimates range from 46 000 to 159 000. This would still mean that death toll as a proportion of the nation's population was greater than in any earthquake in modern times (DesRoches et al. 2011).


Скачать книгу