Characterization of Equivalent Struts for Macromodeling of Infilled Masonry RC Frames Subjected to Lateral Load

Evaluation of the seismic performance of infill frame structural systems using equivalent strut models and pushover analysis has gained popularity due to the simplicity of the evaluation process. Various strut macromodels have been developed for both static and dynamic evaluation of the behavior of the infill frames when subjected to seismic loading. Comparative studies of existing models revealed varying degrees of accuracy, with more detailed models able to produce better results due to improved material characterization and geometric configurations. The variations in the accuracy of model predictions can be linked to the simplifications adopted and/or variances from material behavior modeling of the infill masonry and frame. This paper provides a new approach for developing equivalent strut material and geometric properties that incorporate the behavior of dominant stress zones within the infill. The proposed equivalent strut is represented by dominant stress zones, modeled as nonlinear springs with specific characteristics derived from the dominating stress, and it connects these stress zones either as series or parallel elements. A parametric evaluation of the proposed model was conducted using numerical methods. The performance of the proposed model was validated using experimental data taken from literature. The results show good correlation of the proposed model with the experimental data. (c) 2019 American Society of Civil Engineers.