Comfort evaluation of bridge based on stochastic process theory

Abstract

Vehicle or pedestrian loads can cause bridge vibration. The pedestrian load is essentially a stochastic process, and the vibration response of pedestrian bridges is also a stochastic process. In order to evaluate the human comfort of a pedestrian bridge comprehensively, this paper presents a comfort evaluation method based on stochastic process theory. The autocorrelation function of the displacement response of a pedestrian bridge under random pedestrian load is derived in this paper. On this basis, the root mean square (RMS) of acceleration is proposed as the comfort evaluation index. Taking an asymmetric single-tower cable-stayed bridge as an example, the modal analysis of the bridge is proceeded by finite element method (FEM). Then the acceleration time histories of four measuring points are obtained by fi eld experiment. FEM results and fi eld experiment results are used to analyse random vibration of the bridge. Through a fi eld experiment and random vibration analysis of the bridge, the acceleration peak value evaluation index and the RMS of acceleration value evaluation index are compared. The results show that the RMS of acceleration index is more comprehensive and reasonable because it considers the whole-time history of the vibration response. The RMS of acceleration index is based on stochastic process theory, so it is more rigorous in mathematical expression and clearer in physical concept. It provides a reference for the evaluation of pedestrian bridge comfort.