Evaluation of progressive collapse in URM-infilled RC frames with and without FRP retrofit: 3-D computational simulation of a one story building

July 30, 2010
Publication: Proceedings of the 9th US National and 10th Canadian Conference on Earthquake Engineering|Toronto, Ontario n 824
Author(s): Naguib, Wassim I. Talaat, Mohamed M.

Abstract: Structural systems of reinforced concrete (RC) frames with unreinforced masonry (URM) infill walls are common building systems, especially for historical buildings. In this study a one-story reinforced concrete building was simulated until collapse using scaled records of ground motion, before and after retrofitting the URM infill wall with Fiber Reinforced Polymer (FRP) bars. The nonlinear behavior of the URM-infilled RC frame was modeled using the finite element (FE) software DIANA and laboratory test results from the literature, then idealized using a calibrated strut-andtie model. The infill walls were then modeled, along with the RC frames, using the open source FE code OpenSEES (Open System for Earthquake Engineering Simulation). The OpenSEES modeling uses a direct element removal procedure which accounts for sudden loss of brittle elements taking into account dynamic equilibrium and the transient change in the structural system kinematics. Static and dynamic analytical simulationswere conducted to study the effect of retrofitting the infill walls on the overall behavior of the building system. Finally, the overall building performance after retrofitting was compared to the as-built building system. This study concludes that, after retrofit of the infill walls with FRP bars, the overall displacement ductility and the building system performance were enhanced, without significant increase in the stiffness of the lateral resisting system.