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Basic recommendations for earthquake protection_12

Tham khảo tài liệu 'basic recommendations for earthquake protection_12', khoa học xã hội, kinh tế chính trị phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | EARTHQUAKE RISK MODELLING 347 80000 L0 . . r Unstrengthened Current loss rates unmodified 70000 _ . . . . _ . . 60000 Expected Number of Houses Destroyed in 25 years 50000 40000 30000 Reducing Housing Destruction by Improved Construction . Over a 25 year period assuming e Current seismicity rate Uniform building stock Static population level 1980 Adding .Ringbeam 20000 10000 - All houses - . built to Turkish . Ringbeams BuildingCode Ringbeamsand Cement Mortar Reinforced 0. _ 0 1000 2000 Additional Cost of Improvement per Building US Figure 9.14 Reduction in casualties and housing loss over 25 years with different levels of strengthening after Spence and Coburn 1987a that shown in Figure 7.3 to estimate the total losses which can be expected from all earthquakes over a given period of time. The number of people killed and injured in earthquakes depends on many variables but within a particular rural region with unchanging building technology it is primarily related to the number of buildings which totally collapse D5 . Estimates of numbers of people killed and injured can be derived using an empirical relationship derived from past experience in the area as discussed in Section 9.6 . One of the most important uses of loss estimates of this sort is that they can be used to assess the impact of a building improvement programme of upgrading the traditional houses and to compare the effectiveness of different levels of technology in upgrading if the relative vulnerabilities are known or can be estimated. Figure 9.14 shows the impact over 25 years in the expected numbers of deaths and houses destroyed in eastern Turkey if different levels of strengthening corresponding to some of those shown in Figure 8.12 were generally introduced. Data of this sort can be used in a cost-benefit or cost-effectiveness evaluation of alternative possible government intervention programmes. This is discussed in Chapter 10. 9.8.2 Loss Estimation in Urban Areas For urban loss estimation it