Modeling of masonry infill panels for structural analysis

An analytical macromodel based on an equivalent strut approach integrated with a smooth hysteretic model is proposed for representing masonry infill panels in nonlinear analysis of frame structures. The hysteresis model uses degrading control parameters for stiffness and strength degradation and slippinching" that can be implemented to replicate a wide range of hysteretic force-displacement behavior resulting from different design and geometry. The paper presents the development of the hysteretic model and the definitions of the control parameters, which can be determined using any suitable theoretical model for masonry infills. An available theoretical model for simplified engineering evaluation of masonry infilled frames was explored for estimating the control parameters of the proposed macromodel. The macromodel was incorporated in a nonlinear structural analysis program, IDARC2D Version 4.0, for quasi-static cyclic and dynamic analysis of masonry infilled frames. Simulations of experimental force-deformation behavior of prototype infill frame subassemblies are performed to validate the proposed model. A lightly reinforced concrete frame structure is analyzed for strong ground motions to evaluate the influence of masonry infill panels on the dynamic response.