Investigation of the Dynamic Performance of a Large-Span Suspension Bridge Influenced by Scouring Based on Vehicle-Bridge Coupled Vibration

Qingfei Gao,Biao Wu,Binqiang Guo,Renzhi Wang,Jiaqiang Zhang,Jun Li,Min Luo

doi:10.1155/2020/6656247

Abstract

To study the damage of bridge pile foundations caused by scouring, two damage mechanisms of scouring are proposed in this paper. Considering the vehicle-bridge coupled vibration in terms of two aspects of the scouring depth and erosion depth, the vertical and transversal dynamic characteristics and dynamic responses of the bridge are studied under different cases for the most sensitive vehicle speed. The dynamic characteristics include the 1st and 2nd vibration modes of the vertical and transversal directions of the bridge. The dynamic responses include the vertical and transversal dynamic load allowances and acceleration of the bridge. The souring depth is more sensitive than the erosion depth, and the 2nd vertical mode is most substantially influenced by scouring and erosion. Because of the small value of the natural frequency of the vertical vibration modes, the transversal vibration modes may be more convenient to obtain. The study of the dynamic responses shows that the scouring depth can be represented by the dynamic load allowance in the middle of the span’s section and the erosion depth can be characterized by the dynamic load allowance at the quarter location of the span’s section.

Highlights

Bridges are traffic structures that are used to cross obstacles such as rivers and ravines. ey play a large role in our social life and economic construction
For the bridge pile foundation under the action of water scouring, the soil around the pile is constantly being emptied in the vortex formed by the water flow. is results in scouring pits around the pile foundation, and scouring leads to soil loss around the pile and obvious settlement of the pile foundation under the action of vertical load. e horizontal displacement of the pile foundation under the horizontal load increases due to the decrease in the soil resistance
Is paper uses ANSYS Parametric Design Language for coding. e bridge structure shown in Section 2 and the vehicle model shown in Section 3.1 are used to simulate different erosion depths and different pile foundation crosssection weakening scenarios. e bridge has two piers, and under each pier cap is a pile group composed of 16 piles. e pile group consists of 4 rows, composed of 4 piles in a row, and the radius of every pile is 1.25 m. e length of the pile under the ground is 70 m

Summary

Introduction

Bridges are traffic structures that are used to cross obstacles such as rivers and ravines. ey play a large role in our social life and economic construction. Hydrological effects are the primary cause of the failure of bridge structural functions and safety performance. As the service life increases, it is inevitable that the strength and rigidity of the bridge will decrease due to the erosion of the foundation and further lead to a decrease in safety. For this reason, it is necessary to grasp the technical status and carrying capacity of the bridge in a timely manner during the maintenance process [9]. Ere is less research about the influence of scouring on the dynamic performance of large-span suspension bridges. In this paper, based on vehicle-bridge coupled vibration, the dynamic performance of a large-span suspension bridge influenced by scouring is numerically investigated in detail.

Numerical Model

Dynamic Performance of the Bridge

Findings

Section A