Paper Title
Response Sensitivity for Geometrically Nonlinear Displacement-based Beam-Column Elements

Abstract
Accurate and efficient response gradients are required in structural reliability, optimization and system identification when geometric nonlinearity is simulated for the structural response. The direct differentiation method (DDM) is used to obtain the response sensitivity of the displacement-based beam-column element formulation considering moderate deformations within the basic system. The derived sensitivity equations are implemented in the OpenSees software framework. To validate the sensitivity equations, a comparison between the DDM and finite difference methods (FDMs) is performed through standalone sensitivity analysis for simple example structures. Finite element reliability analysis of a steel frame structure shows that using geometrically nonlinear displacement-based elements affects the probability of failure, relative to that obtained with a geometrically linear element, but not the importance ranking of the uncertain model parameters. Keywords - Frame Finite elements, Geometric Nonlinearity, Sensitivity Analysis, Reliability Analysis