Impedance control method for experimental simulation of traffic vibrations in monolithic bridge widening

Abstract

In monolithic bridge widening, a new deck is constructed alongside the existing deck and a concrete stitch is cast to connect both decks. Due to practical reasons it is often required to maintain traffic flow during casting of the concrete stitch [1,2]. As a result, the curing concrete stitch would be subjected to traffic vibration, whose amplitude decreases as the concrete stitch gains strength [3,4]. There had been a lack of proper control algorithm to simulate such loading condition, and thus widely different results of vibration resistance of concrete stitches had been reported [4,5]. To address this gap, an impedance control method for experimental simulation of traffic vibrations has been developed by the authors. At any vibration cycle during 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 new test method, a series of concrete stitch specimens have been tested by subjecting to different vibration amplitudes for establishing reliably traffic vibration limits in bridge widening projects. REFERENCES [1] D.G. Manning, Effects of Traffic-Induced Vibrations on Bridge-Deck Repairs, National Cooperative Highway Research Program Synthesis of Highway Practice 86, Transportation Research Board, National Academy of Sciences, Washington DC, USA, 1981, 40pp. [2] H.L. Furr, F.H. Fouad, Effect of moving traffic on fresh concrete during bridge-deck widening, Transportation Research Record No. 860 (1982) 28-36. [3] P.L. Ng, A.K.H. Kwan, Structural failure of concrete stitch in bridge widening and its mitigation, in: C.M. Wang, K. Murugappan (Eds.), Proceedings of International Conference on Structural and Foundation Failures, Singapore, 2004, pp. 113-122. [4] P.L. Ng, J.S. Du, X.R. Hui, G. Kaklauskas, Evaluation of traffic vibration mitigation measures for curing concrete stitch in bridge widening project, in: C.K. Choi (Ed.), Proceedings of the 2011 World Congress on Advances in Structural Engineering and Mechanics, Seoul, Korea, 2011, pp. 1573-1590. [5] J.S. Du, P.L. Ng, F.T.K. Au, Highway bridge widening: Structural considerations and research needs, in: J.J. Gao, J. Lee, J. Ni, L. Ma, J. Mathew (Eds.), Proceedings of the 3rd World Congress on Engineering Asset Management and Intelligent Maintenance Systems, Beijing, China, 2008, Springer-Verlag, pp. 436-441