Modeling of masonry buildings subjected to seismic actions still represents an open problem in structural engineering. The equivalent frame model is the most used approach to analyze the seismic behavior of both existing and new masonry constructions but, despite this, several aspects are being researched to improve its effectiveness. Among these, modeling of spandrel panels plays a key role to correctly analyze the in-plane seismic response of unreinforced masonry walls. Actually, horizontal mono-dimensional beam-like elements provided of both strength and displacement capacity are used to schematize the spandrel panels, also according with the most of current national and international codes.

In this paper an alternative strut and tie scheme to model the spandrel panels, suitable to be used within the equivalent frame approach, is presented: the compressed masonry material is schematized with an equivalent diagonal no-tension truss, whose length and effective compressed area are obtained with limit equilibrium conditions, while tensile-resistant element is represented by no-compression truss. Such model allows a more realistic representation of the mechanical behavior of spandrels because both amount of axial force within the spandrel and the reduced elastic flexural and shear stiffness due to progressive cracking of material are taken into account. Moreover, the local failures of both compressed masonry and/or tensile-resistant elements are better identified and, consequently, also the failure mechanisms of the whole equivalent frame are better detailed.

The proposed schematization has been used to simulate the seismic behavior of some reference case studies of existing masonry walls, strengthened with different steel ties arrangement. These walls have been modelled with a hybrid equivalent frame model which consists of mono-dimensional beam-like element for piers, fully rigid offsets for the nodal panels and a strut and tie scheme for spandrels.

受地震作用的砖石建筑的建模仍然是结构工程中的一个开放问题。等效框架模型是分析现有和新砌体结构的抗震性能的最常用方法，尽管如此，仍在研究多个方面以提高其有效性。其中，对无筋砌块墙的面内地震响应进行正确分析时，跨度板的建模起着关键作用。实际上，提供的强度和位移能力兼具的水平一维梁状元件也可以用来示意跨接板，这也符合大多数当前的国家和国际法规。

在本文中，提出了一种适用于等价框架方法的跨接板建模的替代支撑和系结方案：压缩的砖石材料用等效的对角无拉力桁架进行图解，其长度和有效压缩面积为在极限平衡条件下获得抗拉强度，而无压缩桁架则代表抗拉强度。这样的模型可以更真实地反映跨度的机械性能，因为考虑了跨度内的轴向力大小以及由于材料逐渐破裂而降低的弹性挠曲和剪切刚度。此外，可以更好地识别受压砖石和/或抗拉构件的局部失效，因此，

拟议的方案已被用来模拟现有参考砌体墙的抗震性能，并通过不同的钢扎带布置进行了加固。这些墙采用混合等效框架模型进行建模，该模型包括用于墩的一维梁状元件，用于节点面板的完全刚性偏移以及用于翼梁的撑杆和系固方案。