提高建筑结构抗地震倒塌能力的设计思想与方法

工程结构的抗震能力是社会抗震防灾系统的第一道防线。建筑物的倒塌是造成地震灾害的主要原因。建筑物在地震中的破坏程度,大体决定了震害的严重程度。因此,建筑结构的抗震能力,特别是抗地震倒塌能力,是地震区抗震防灾能力的最重要组成部分。文中运用系统科学的思想,介绍了提高建筑结构整体抗震能力的设计思想,结合汶川地震中建筑震害的教训,重点针对建筑结构抗地震倒塌能力,讨论了建筑结构抗震设计中应注意的问题和改进建议。研究结果表明:建筑结构系统的安全储备分为基本安全储备、整体安全储备与意外安全储备三个层次。结构的整体抗震能力和抗地震倒塌能力取决于整体安全储备和意外安全储备,意外安全储备不足是汶川地震建筑结构震害严重的主要原因。结构系统的意外安全储备主要来自其鲁棒性、整体稳定性和整体牢固性。目前对于结构系统的整体安全储备和意外安全储备的研究很不够,结构设计规范的相关规定和要求也有待进一步完善。

Collapse prevention of building structures:a lesson from the Wenchuan earthquake

The aseismic capacity of engineering structures is the first line in the earthquake defense system of the society.Building collapse is one of the major earthquake devastating consequences.Damages of buildings generally reflect the degree of earthquake disaster.As a result,the aseismic capacity of building structures,especially their capacity to prevent collapse,is of great importance to the overall earthquake defense system of the society.Based on analyzing the building seismic damage in the Wenchuan earthquake,methods to increase the overall aseismic capacity of building structures are discussed in the framework of system theory.Some key problems and suggestions for seismic design,especially for increasing the capacity to prevent collapse of building structures are proposed.It is shown that: the safety margin of building structural systems can be divided into 3 levels: fundamental,integral and unexpected safety margins.The overall seismic capacity and collapse prevention of building structures are mainly determined by the integral safety margin and unexpected safety margin.Lack of unexpected safety margin is the main reasons of the severe building damage in the Wenchuan earthquake.The unexpected safety margin of a structural system mainly comes from its robustness,stability and integrity.Research on the integral and unexpected safety margins of building structures is still limited.Corresponding requirements and specifications in current design code for building structures need to be improved.