FEMA P695 proposes quantification of soil-structure effects as a field of research to adjust the collapse margin ratio. The Winkler foundation with elastic and inelastic stiffness is used to address interaction effects. Three-, nine- and 20-story steel moment-resisting frame buildings are selected, and the collapse margin ratio of the buildings for site classes C and D are evaluated. The nonlinear soil behavior leads mostly to an increase in seismic collapse probability compared to linear soil behavior and fixed-base conditions. Finally, simplified adjustment equations are proposed for estimating the collapse margin ratio of structures considering the soil-structure interaction effects.

FEMA P695建议对土壤结构效应进行量化，作为调整坍塌裕度比的研究领域。具有弹性和非弹性刚度的Winkler基础用于解决相互作用效应。选择三层，九层和二十层的抗弯钢框架建筑物，并评估场地等级C和D的建筑物的倒塌裕度比。与线性土壤行为和固定基础条件相比，非线性土壤行为主要导致地震倒塌概率的增加。最后，提出了考虑土-结构相互作用效应的结构倒塌裕量比的简化调整方程。