Impedance-control technique for physical simulation of traffic vibration effects in monolithic bridge widening

Abstract

In monolithic bridge widening, a new deck is constructed alongside the existing deck and then a concrete stitch is cast to connect both decks. Due to practical reasons, it is often required to maintain traffic flow during placement of the concrete stitch. As a result, the curing concrete stitch would be subjected to traffic vibration, whose amplitude decreases as the concrete stitch gains strength and stiffness. There had been a lack of proper control algorithm to physically simulate such loading condition, and thus widely different results of vibration resistance of concrete stitches had been reported. To address this gap, an impedance-control technique for experimental simulation of traffic vibration effects has been developed. At any vibration cycle during physical testing, the load applied by the hydraulic actuator to the concrete stitch specimen is automatically determined from the force and displacement feedback signals in the previous vibration cycles. The actuation system is real-time computer controlled by a bespoke impedance-dependent control programme. With the use of this novel testing methodology, a series of concrete stitch specimens have been tested by subjecting to different vibration amplitudes for establishing reliable traffic vibration limits in bridge widening projects.