Evaluating inelastic displacement demand of structures exposed to seismic hazard is required for the design of new buildings as well as for seismic risk assessment of existing structures. Most of the buildings are designed to withstand strong earthquakes by responding in the nonlinear range. Having special parts of the structure designed to develop a stable hysteretic behaviour allows the structure to deform in order to accommodate the displacement demand imposed by strong ground motions. This paper is centred on finding a correspondence between the maximum elastic and inelastic displacement responses of the single degree of freedom (SDOF) systems subjected to earthquakes generated by Vrancea seismic source. Vrancea intermediate-depth earthquakes are responsible for the seismic hazard throughout Romanian territory. They have distinctive features, such as large displacement demand and large predominant periods, which makes Romania a special seismic environment. Using a database of Romanian and Japanese strong ground motions generated by intermediate-depth earthquakes and performing nonlinear dynamic analysis on the SDOF oscillators following the Takeda model, this study estimates the inelastic to elastic displacement ratio of reinforced concrete systems. Soil conditions, epicentral distance and magnitude influence on inelastic response is analysed using constant ductility response spectra. The main findings of the study are: the local increase of the inelastic to elastic displacement ratio for type C soil (Eurocode 8 classification) for large magnitude earthquakes and the significant effect of soil conditions on the inelastic response of the SDOF systems. The inelastic amplification was evaluated using a functional form depending on system ductility, soil conditions and earthquake magnitude.

新建筑的设计以及现有结构的地震风险评估都需要评估暴露于地震危险中的结构的非弹性位移需求。大多数建筑物都设计为通过在非线性范围内响应来承受强地震。将结构的特殊部分设计为产生稳定的滞后行为，允许结构变形，以适应强地面运动施加的位移需求。本文的重点是寻找受 Vrancea 震源产生的地震影响的单自由度 (SDOF) 系统的最大弹性和非弹性位移响应之间的对应关系。Vrancea 中等深度地震是造成整个罗马尼亚领土地震危险的原因。它们具有鲜明的特点，如大位移需求和大优势周期，使罗马尼亚成为一个特殊的地震环境。本研究使用由中深度地震产生的罗马尼亚和日本强地震动数据库，并根据武田模型对单自由度振荡器进行非线性动力分析，估计钢筋混凝土系统的非弹性与弹性位移比。使用恒定延性响应谱分析土壤条件、震中距离和幅度对非弹性响应的影响。研究的主要发现是：C 类土壤（欧洲规范 8 分类）在发生大地震时的非弹性与弹性位移比的局部增加以及土壤条件对单自由度系统的非弹性响应的显着影响。