Past earthquakes have repeatedly shown that damage to masonry infills can produce large economic losses and even jeopardize human lives. Nevertheless, in current design practice masonry infills are ignored, while available macro-models for nonlinear analysis focus the attention on the In-Plane (IP) behavior of masonry infills only, while neglecting the Out-Of-Plane (OOP) collapse mechanism. The main objective of this study is to investigate the seismic performance of RC frame buildings accounting for the interaction between IP and OOP behavior of masonry infills. To this end, a suitable nonlinear model, able to capture the IP stiffness and strength reduction due to the OOP displacement demand (and vice versa) is implemented. The selected model incorporates a routine that removes infills from the structural model when either IP or OOP collapse occurs. Different building models, representative of typical residential buildings, realized in Italy (and other European countries) from 50’s to 90’s, are examined through nonlinear response-time history analysis at different earthquake intensity levels, with return period ranging from 30 to 5000 years. Two alternative infill configurations (single layer and double layer with inner cavity) are considered, in accordance with the construction practice of the time. The comparison between the models with and without IP/OOP interaction points out the relevance of the OOP behavior towards an accurate evaluation of the seismic performance of RC frame buildings. A set of fragility curves is tentatively proposed, for different building performance levels, ranging from immediate occupancy to life safety.

中文翻译：

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RC框架建筑物的抗震性能考虑了砌体填充物的平面外行为

过去的地震屡次表明，破坏砖石填充物会造成巨大的经济损失，甚至危及人类的生命。但是，在当前的设计实践中，忽略了砌体填充物，而用于非线性分析的可用宏模型仅将注意力集中在砌体填充物的面内（IP）行为上，而忽略了面外（OOP）塌陷机制。这项研究的主要目的是研究考虑到砌体填充物的IP和OOP行为之间相互作用的钢筋混凝土框架房屋的抗震性能。为此，实现了一个合适的非线性模型，该模型能够捕获由于OOP位移需求而引起的IP刚度和强度降低（反之亦然）。选定的模型包含一个例程，当IP或OOP崩溃时，该例程将从结构模型中删除填充。通过在不同地震烈度级别下的非线性响应时间历史分析，研究了在意大利（和其他欧洲国家）从50年代到90年代实现的代表典型住宅建筑的不同建筑模型，其返回期为30到5000年。根据当时的施工惯例，考虑了两种可选的填充结构（单层和双层内腔）。具有和不具有IP / OOP交互的模型之间的比较指出了OOP行为与精确评估RC框架建筑物的抗震性能的相关性。初步提出了一组脆性曲线，