Design and control of high-speed railway bridges equipped with an under-deck adaptive tensioning system

Abstract

This work investigates the application of an external adaptive tensioning (EAT) system for high-speed railway (HSR) bridges. The design of HSR bridges involves strict displacement and acceleration limits, which typically results in oversizing. The EAT system comprises under-deck cables deviated by compressive struts that are equipped with linear actuators. Since the cable is eccentric to the bridge neutral axis, tensioning the under-deck cables by adjusting the length of the linear actuators generates a bending moment that counteracts the effect of the external loads. The response under variable loading is reduced by computing the actuator commands with a linear quadratic regulator (LQR). Numerical results show that active control through the EAT system allows satisfying displacement and acceleration limits, which otherwise cannot be met without increasing the stiffness and mass of the bridge. A significant reduction of the response is achieved when resonance conditions occur. In addition, peak stresses are significantly reduced, showing the potential for fatigue-life extension. Parametric analyses comparing different bridge depths and spans, EAT system dimensions, controller parameters and actuator placement are carried out to investigate system efficacy. Results show that the adaptive bridge solution can achieve up to 32% mass savings compared to an equivalent passive bridge.