Recommendations for Modelling Lightly Reinforced Concrete Walls using PERFORM-3D

Presented by Anahid Behrouzi, California Polytechnic State University


Description: Due to poor performance in NZ (2010-11) and Chile (2011) earthquakes, there is concern regarding the ductility of pre-1980s concrete shear walls that typically have low longitudinal reinforcement ratios and lack boundary elements. This has motivated large-scale experiments of lightly reinforced walls at the University of Auckland (Lu et. al. 2017) and Cal Poly (de Sevilla et. al. 2019). The researchers utilized data from these two test programs, along with recommendations from Lowes et. al. (2016), to calibrate computational wall models in the nonlinear analysis software PERFORM-3D. The presentation will discuss the impact of wall modelling parameters including mesh refinement, concrete and steel constitutive models, and P-delta effects on static pushover and cyclic results related to initial stiffness, yield/nominal/ultimate strength and associated drift, as well as energy dissipation. Since ductility is one of the primary concerns with these older walls, a precise determination of ultimate drift is critical. However, PERFORM-3D often significantly over-estimates this value. As a solution, the researchers implemented axial strain and rotation gages in the PERFORM-3D models to identify material and ASCE 41 performance limit states, allowing for a more accurate determination of ultimate drift. The presentation will conclude with the research team’s wall modelling recommendations for PERFORM-3D, as a refinement of Lowes et al. (2016). Thus, enabling practitioners to more accurately predict the response of lightly reinforced concrete walls. This work fits into a larger objective of supporting structural engineers as they are tasked with analyzing and retrofitting existing reinforced concrete buildings in seismic regions.