Modeling Abutment Contact-Friction Using Run-Time Parameter Updates

Nonlinear modeling of seat-type abutment behavior has evolved during response history analysis from simple linear elastic springs or single-point constraints to more refined models of bearing, back wall, shear key, and back fill contributions. While most longitudinal models consider the gap closure effect, only select few studies have looked at the different possible contact-friction responses that are generated, particularly in the case of skewed abutments. This paper presents nonlinear static and nonlinear dynamic results for several abutment and bridge scenarios based on a novel modeling approach developed by the authors. The Coulomb contact-friction interface (at several locations between the superstructure, back wall, and shear keys) is modeled using only linear elastic (or elastic-perfectly-plastic) springs that undergo user-driven runtime parameter updates during the analysis. The parameterization method was previously benchmarked against classical solutions from node-to-node contact literature, and in this paper is extended to studying the response of abutments in OpenSees. Results are presented for two simplified cases of rigid superstructures relative to results from the literature. The nonlinear static and dynamic behaviors of the abutment are then extended to response history analysis of standard reinforced concrete overpass bridges as compared with other common abutment modeling approaches. Results demonstrate scenarios where friction after contact changes the frequency response and therefore demand in the bridge system as well as when it may be neglected entirely