The problem of implied margin of safety in seismic design codes is examined — with particular reference to the Indian standard IS-1893. A framework for estimation of available margin of safety for earthquake resistant design is developed based on serviceability limit state using linear random vibration theory. Inadequacy of seismic zonation in ensuring the objective of uniform level of safety within each zone is shown with reference to differences in the available margins of safety for buildings designed for similar seismic zones but in distant geographical locations. Subsequently, the proposed reliability framework is extended to the problem of estimating residual life of earthquake damaged structures and also for developing a decision framework for planning of maintenance and repairs.

研究了抗震设计规范中隐含的安全裕度问题，特别是参考了印度标准IS-1893。基于使用寿命极限状态，使用线性随机振动理论，建立了抗震设计可用安全裕度估算框架。参照为类似地震带但在遥远地理位置设计的建筑物的可用安全裕度的差异，显示了地震分区不足以确保每个区域内的安全等级均一的目标。随后，提出的可靠性框架扩展到估计地震损坏结构的剩余寿命的问题，并且还扩展到用于制定维护和维修计划的决策框架的问题。