Modelling of Unreinforced Masonry Infill Panels

Commercial and residential buildings are usually constructed of steel or reinforced concrete frames with unreinforced masonry infill panels.Many codes of practice ignore the stiffness during design process for ease of design.Many designer engineers also do not know how to incorporate this additional stiffness from the unreinforced masonry infill panels into the design process.This leads to an incorrect assessment of the building's robustness when subjected to lateral loading and especially when subjected to seismic ground motion.The natural frequencies, corresponding mode shapes and the strength of the building is therefore incorrectly assessed leading to an overdesign.When these buildings are modelled using Finite Element Analysis, it is imperative that the strength of the unreinforced masonry infill panels are correctly accounted for, to prevent over strengthening the columns to yield the same experimental test results.The paper therefore focuses on describing the possible failure modes caused by unreinforced masonry infill panels on reinforced concrete framed structures and the FE modelling techniques required to obtain a computationally efficient model.The investigation shows the significant effect of the unreinforced masonry infill panels on the robustness of the global model.