Despite extensive research studies, the seismic response of infilled reinforced concrete buildings remains an open problem due to both the complexity of the interaction between the infill and the frame and the large number of parameters involved. Thus, guidelines for both modelling and analysis are still lacking and the infill walls are normally treated as nonstructural components in seismic codes. However, it may be not conservative to neglect the influence of infills. In fact, the infill masonry walls may significantly affect the stiffness, strength, and energy dissipation capacity of RC buildings, even when they are regularly distributed. Recognizing this influence and its importance on the vulnerability of infilled frames, Eurocode 8 requires amplifying seismic action effects due to infills. In this paper, the effectiveness of the Eurocode 8 design provisions for infill irregularity in plan and/or elevation was investigated. To this aim, different in-plan layouts of infill walls were selected as marginal cases for which Eurocode 8 does not require amplification of the action effects due to the presence of infills, or the additional measures to counteract these effects are not mandatory. The seismic vulnerability of the infilled RC buildings was evaluated using nonlinear static and nonlinear dynamic analyses. Both cracking and crushing of masonry and stiffness and strength degradation were considered in the analysis. The effect of the layout of the masonry infills on the seismic response in terms of resistance and displacement was evaluated. Results show that in one of the case studies here examined, it is not conservative to neglect the influence of infill panels. In fact, structural failure due to torsion and soft-storey effects may occur even in cases where Eurocode 8 does not require the amplification of the action effects. Finally, the total shear demand on columns may be underestimated, even in cases where the code provisions for infills irregularity are not mandatory, and the additional shear demand in the columns induced by the masonry infill is very low.

中文翻译：

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砌体填充物的不规则性对RC建筑非线性抗震性能的影响

尽管进行了广泛的研究，但由于填充物与框架之间相互作用的复杂性以及所涉及的大量参数，填充钢筋混凝土建筑物的地震响应仍然是一个悬而未决的问题。因此，仍然缺乏建模和分析的指南，并且在地震法规中通常将填充墙视为非结构性组件。但是，忽略填充物的影响可能并不保守。实际上，即使规则分布，填充砌体墙也可能显着影响RC建筑物的刚度，强度和能量消散能力。认识到这种影响及其对填充框架脆弱性的重要性，Eurocode 8要求放大填充物引起的地震作用影响。在本文中，研究了欧洲规范8设计规定对平面和/或立面中的填充物不规则性的有效性。为此，选择了不同的填充墙平面布置图作为边缘案例，对于这些案例，由于存在填充物，Eurocode 8不需要放大作用效果，或者没有强制措施来抵消这些效果。使用非线性静态和非线性动力分析评估了RC填充建筑物的地震脆弱性。分析中考虑了砌体的开裂和破碎以及刚度和强度下降。评估了砌体填充物的布局对地震反应的抵抗力和位移的影响。结果表明，在这里研究的一个案例研究中，忽略填充面板的影响并不保守。实际上，即使在Eurocode 8不需要放大作用效果的情况下，也可能会发生由于扭转和软层作用引起的结构破坏。最后，即使在对于填充物不规则性的法规规定不是强制性的情况下，并且由于砌体填充物引起的列中的额外剪切需求非常低的情况下，也可能低估了圆柱体上的总剪切需求。