Mitigating Pedestrian Bridge Motions Using a Deployable Autonomous Control System

Abstract

A new concept for a deployable autonomous control system (DACS) was recently developed by the authors to achieve short-term vibration mitigation in lightweight structures. With the details of the deployability and autonomy aspects having already described, this article focuses on experimentally evaluating the performance of the DACS in suppressing the lateral vibrations of pedestrian bridges. A real-time hybrid simulation (RTHS) methodology was employed as the experimental tool to achieve this goal. In the RTHS procedure employed in this study, the pedestrian bridge was modeled numerically, and the DACS was tested physically on a hydraulic shake table that reproduced the bridge displacements. The RTHS methodology is a well-established experimental technique for lumped-parameter building structures, but it involves implementation challenges when applied to pedestrian bridges where the location of the load is spatially varying. Using modal decomposition principles, a discrete state-space formulation is presented that can be used for the RTHS of bridges. This method allows moving loads and DACS mobility to be considered during RTHS. Following the experimental modeling of the DACS prototype, the reliability of the characterized DACS model was validated through a series of single-degree-of-freedom hybrid simulations. The RTHS of a pedestrian bridge equipped with the DACS was carried out to experimentally evaluate the effectiveness of the DACS. A linear-quadratic Gaussian-based controller capable of compensating for the interaction effects between the structural response and DACS is presented.