我国是一个多地震国家。过去,由于地震区房屋大部未作抗震设防或设防能力不足,历次强烈地震中都造成大量人身伤亡和经济损失。很多已建建筑都需要进行抗震加固。据统计仅北京、天津等二十 Our country is a multi-earthquake country. In the past, due to the fact that most of the houses in the seismic area were not equipped with seismic fortification or lack of fortification capabilities, a number of strong earthquakes have caused a large number of personal injuries and economic losses. Many existing buildings require seismic reinforcement. According to statistics, only Beijing, Tianjin and other twenty