Abstract
When vehicles interact with a bridge, a vehicle–bridge interaction (VBI) system is created. The frequency and modal shape of VBI systems have been widely studied, but the damping of VBI systems has not been adequately investigated. In recent years, several incidents of abnormal bridge vibration due to changes in bridge damping have occurred and aroused widespread concern in society. Damping is an important evaluation index of structural dynamic performance. Knowing the damping ratio of a VBI system is useful for analyzing the damping changes while a bridge is in service. This paper presents a method to extract bridge damping values from a VBI system, which can serve as a guide for bridge damping evaluation. First, a double-beam theoretical model was used to simplify the VBI system for cases involving uniform traffic flow. The damping ratio equation for the simplified VBI system was obtained using the extended dynamic stiffness method (EDSM). A double-beam finite element model and a VBI finite element model were established. The damping ratios of the two models were separately calculated and then compared with the simplified VBI model results. The results verified the accuracy of the simplified method. This paper then explains that bridge damping values can be extracted by estimating the equivalent traffic flow parameters and using the damping formula for the simplified VBI system. The bridge damping ratios extracted using this method in an engineering case ranged from 0.75% to 0.78%, which is smaller than the range that was directly identified using monitoring data (0.83–1.19%). The results show that the method can effectively extract bridge damping ratios and improve damping ratio identification.
Highlights
Vehicle–bridge interaction (VBI) has been extensively studied in the field of structural health monitoring (SHM) [1]
In order to study the effect of traffic on the dynamic characteristics of bridges, Dan [14] proposed that the double-beam system can be used to analyze the damping variation law of VBI systems
An estimation method of equivalent traffic flow parameters was proposed to achieve the evaluation of bridge damping from the dynamic characteristics of VBI systems
Summary
Vehicle–bridge interaction (VBI) has been extensively studied in the field of structural health monitoring (SHM) [1]. In order to study the effect of traffic on the dynamic characteristics of bridges, Dan [14] proposed that the double-beam system can be used to analyze the damping variation law of VBI systems. An estimation method of equivalent traffic flow parameters was proposed to achieve the evaluation of bridge damping from the dynamic characteristics of VBI systems. Uniform traffic flow refers to traffic flow in which each vehicle has the same dynamic parameters (e.g., the distance between vehicles is the same and the traffic flows at the same speed) Where mv is the average mass of vehicles on the bridge; kv and cv are the average vehicle stiffness and the average vehicle damping factor, respectively; n is the number of vehicles on the bridge; and L is the bridge length
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