阅读选择 
阅读下面短文,请从短文后所给各题的4个选项( A、B、C、D)中选出1个最佳选项。   

     Engineering design aims to link economic, social, environmental and of course safety factors to produce the best solution. This is especially true in earthquake engineering where it is possible to design a building that is “safe” for all types of earthquakes but does not fit the design brief. For example, it is not economically feasible to design buildings in Bristol to withstand a large earthquake as the chances are very small. Similarly a square concrete structure that has small windows and thick walls may be the ideal design for a particular area; however, it wouldn’t fit a design brief asking for a modern high-tech design. This balance of factors can only be achieved by engineers combining experience and knowledge of the area where the structure is to be located.
     Design practice has been changing over the last few years. The older design requirements used to insist that in an earthquake the building should maintain enough structural integrity to remain standing. This meant that if the serviceability limit state was passed the structure would have to be demolished, as it would be no longer safe to use. Although this concept saves lives as people can escape from buildings, it does nothing to prevent the huge financial cost of a large earthquake as a large proportion of buildings have to be demolished and rebuilt. Thus the new design requirements demand that the structure should remain standing in an earthquake and additionally not have to be demolished.
     The other factor often left unconsidered is the effect of after shocks. These shocks generally have little effect on undamaged buildings; however, on damaged ones they can have destructive effect and stop rescue operations. In the assessment of buildings the energy from an aftershock should be considered.
     Apparently the damage caused by earthquakes is almost entirely associated with man-made structures. Earthquakes only cause death by the damage they induce in structures such as buildings, dams, bridges and other works of man. And this is one of the reasons why earthquake engineering is so important.