Structural health monitoring (SHM) of bridges has gained rapid development in the past few years. This paper describes application of SHM on long-span bridges in China, with the aim to illustrate its practical value. A short review of its development and practice is firstly introduced. Three case studies are subsequently presented on utilization of SHM data in engineering practice. In the first case study, a ship collision incident is analyzed using SHM data. An alarm is sent and confirmed when the collision occurred, and mode parameters are identified with GPS measurements to evaluate the bridge condition. In the second case study, damage of expansion joints in a suspension bridge is assessed with girder end displacement measurements. Malfunction of viscous damper is found to correlate with cumulative displacement. The results show that cumulative displacement can be used for condition assessment of expansion joints. In the third case study, the performance of tuned mass dampers is evaluated with wind and vibration measurements before and after tuned mass damper installation. Through explanation of these case studies, the paper illustrates how to distill useful insights from SHM data, which could be instructive for further research in this field.

Premature failure of expansion joints is a concern for bridge owners. After opening to traffic, the Jiangyin suspension bridge experienced frequent damage in expansion joints, and the problem remained unsolved even after replacement with new expansion joints and installation of viscous dampers at the girder end. This paper aims to clarify the failure mechanism of the expansion joints based on field test results. The field tests consist of three scenarios: static test, influence line test, and truck pass-by test. The tests aimed to investigate the behavior of expansion joints on both global and local scales. In the static and the influence line tests, it was found that strain response of the expansion joint is affected by the girder deformation, which reflects effect of global behavior of the bridge on the expansion joints. The truck pass-by test result shows that direct impact of heavy truck axles could induce high strain in expansion joints, which indicates that the expansion joints are affected ...

Chongqi Bridge is part of an important route over the Yangtze River connecting Chongming City in Shanghai with Qidong City in Jiangsu. The steel box-girder bridge consists of separate but adjacent twin six-span bridges, and each is 16 m wide and 944 m long. During construction of the bridge, vortex-induced vibration (VIV) was observed, which caused concern about the performance of the bridge. A vibration test was conducted and an eigensystem realization algorithm (ERA) was performed to identify mode properties of the bridge. A wind tunnel test showed that VIV could occur in the first vertical mode, and tuned mass dampers (TMDs) were installed in the four middle spans of the bridge to control large vibrations. A structural health monitoring (SHM) system was also deployed on the bridge and the TMDs, which includes anemometers, accelerometers, displacement transducers, and so on. On July 10–12, 2015, Typhoon Chan-hom passed through the area near Chongqi Bridge. Wind characteristics were calculated with monitoring data, and the response of the bridges and the TMDs were evaluated under Typhoon Chan-hom. The results indicate effectiveness of the TMDs and their functioning under different wind conditions. An effectiveness factor is proposed to describe the functioning of TMD to mitigate deck vibration, which is illustrated with the acceleration measurements of the deck and the TMDs.

Among components of a suspension bridge, suspenders transmit wind or live loads on the deck to the main cable, which are then transmitted to the pylons, and finally to the earth. Suspenders are vulnerable to corrosion caused by harsh environments and fatigue due to live loads, and they often have a shorter life span than that of other components. In this paper, premature failure of short suspenders in a suspension bridge is investigated with monitoring data and finite-element (FE) simulation, and a replacement method is proposed and implemented on the bridge. The investigation and discussion in the paper is fourfold. First, premature failure of the short suspenders in a suspension bridge is investigated, with the most severe damage found to be in the cylindrical bushing of the pin connection between the suspenders and the deck. Second, monitoring data analysis and FE simulation are conducted to find out the reasons for the premature damage of the short suspenders. Third, a replacement method using temporary suspenders was proposed, and field implementation of suspender replacement was performed. Finally, conclusions are drawn that could shed light on the maintenance and replacement of short suspenders in suspension bridges.

Displacement is an essential indicator of the functioning and safety of long-span cable-supported bridges under operational conditions. However, displacement estimation is challenging as these bridges are simultaneously subjected to various loading conditions such as temperature, wind, and vehicles. This article investigates an approach for estimating bridge displacement responses under multiple loads using a residual autoencoder model. Monitoring data of a cable-stayed bridge are collected to validate the proposed approach, including comprehensive measurements of the various loads and the displacement responses. Characteristics of temperature, wind, and vehicle loads are taken as the input, and the displacement responses at the mid-span of the main girder and top of the two pylons are taken as the output. The results showed the effectiveness of the proposed approach with an accuracy higher than 95%, which clearly outperformed other models such as long short-term memory networks in accuracy and efficiency. The effects of different types of loads are also investigated, and the wind load is found to be the most influential. Furthermore, multistep ahead prediction is carried out using the proposed approach, and good accuracy is achieved even 5 min ahead. The proposed approach can shed light on early warning of the malfunction of the bridge.