Reliability sensitivity estimation of nonlinear structural systems under stochastic excitation: A simulation-based approach

• Reliability is defined in terms of first excursion probabilities.
• Proposed approach is a simple post-processing of subset simulation.
• Sensitivity analysis is performed for different levels of system reliability.
• Proposed approach is applicable for complex nonlinear systems.
• Sensitivity information gives a valuable insight into the system reliability.

This work explores the feasibility of using advanced simulation-based methods for reliability sensitivity analysis of nonlinear structural systems subject to stochastic excitation. Reliability is defined in terms of a first excursion probability which measures the chances that uncertain structural responses exceed in magnitude prescribed threshold levels within a specified time interval. The proposed reliability sensitivity analysis consists of applying a simple post-processing step associated with an advanced sampling-based reliability analysis. It does not require any additional system response evaluations. In addition, the method provides information about the whole trend of the reliability sensitivity estimates in terms of the threshold levels. The approach is validated on two nonlinear structural models under stochastic ground excitation.