Finite-Element Simulation of Posttensioned Steel Connections with Bolted Angles under Cyclic Loading

Abstract

Steel beam-column connections with posttensioned (PT) elements are proven systems that can provide adequate stiffness, strength, and ductility, while eliminating permanent deformations in a moment-resisting frame subjected to seismic loading. In this study, detailed three-dimensional finite-element (FE) models of steel beam-column connections with PT strands are developed and analyzed under cyclic loading. Efforts are made to overcome challenges in performing the nonlinear FE analysis of large-scale PT connections, which involves gap opening and closing behavior as well as contact and sliding phenomena. Geometric and material nonlinearities, preloaded bolts and strands are also considered in the modeling. Through a verification study, the results from the FE models are validated against prior experiments on interior PT connections with top-and-seat angles. Parametric studies are also conducted to investigate the effects of three factors on the cyclic performance of PT connections. The factors investigated in this study are: the presence of beam flange reinforcing plates, the yield strength and strain hardening of steel angles, and the amount of initial posttensioning force in the strands.