Abstract
As a critical component of a suspension bridge, the integrity of the suspenders plays a critical role in the serviceability and reliability of the bridge during its life time. Despite the wide recognition of the importance of the suspenders, very few studies have been devoted to the condition evaluation of suspenders in operation. The present study performs the fatigue assessment on the suspenders accounting for the stochastic wind and traffic loads using the in-situ monitoring data. To this end, a probabilistic numerical framework is proposed to predict the time-dependent fatigue reliability of the suspenders under stochastic wind and traffic loads during the bridge’s life time, based on the linear fatigue damage rule. As a demonstration, the proposed numerical framework is applied to a long-span suspension bridge located in a mountainous canyon. The results indicate that it is of paramount importance to consider both the wind and traffic load effects in the fatigue reliability evaluation of the suspenders. In addition, it was also found that among the suspenders under investigation, the short suspender at the bridge mid-span (S36) is more prone to the fatigue damage, while the long suspender at the end of the bridge girder (S2) is less prone to the fatigue damage. Finally, provided with a target reliability index of 3.0, the fatigue life of the suspenders S36 and S2, considering the life time wind and traffic load, is estimated as 53 years and 167 years, respectively. The present research could provide essential guidelines for the optimization of inspection and replacement in maintenance practices for suspenders.
Highlights
Owing to the excellent spanning capacity and graceful appearance, more and more suspension bridges have been constructed/designed in recent years, serving as critical links in transportation networks, in order to cross larger water bodies, straits, or canyons
The suspension bridge is composed of a steel truss girder, concrete pylons, cables, and suspenders, which is modeled as a 3D finite-element model in ANSYS 15.0
The time-dependent fatigue reliability of the suspenders considering life time stochastic wind and traffic loads was evaluated based on fully coupled traffic-bridge-wind (TBW)
Summary
Owing to the excellent spanning capacity and graceful appearance, more and more suspension bridges have been constructed/designed in recent years, serving as critical links in transportation networks, in order to cross larger water bodies, straits, or canyons. Deng et al [15] presented a probabilistic fatigue assessment approach for suspenders based on structural monitoring, where the stochastic traffic was simulated using the Monte Carlo method. Even if the traffic flow is considered, critical parameters in the traffic flow, e.g., the vehicle type, vehicle speed, gross vehicle weight, and vehicle lane occupancy ratio, were not or only partially considered Such simplification ignores the coupling effects between the traffic flow and the bridge, which may have significant influence on the dynamic behavior of the suspender and the resultant fatigue performance [16]. A probabilistic fatigue framework is proposed to evaluate the fatigue performance of the suspenders under stochastic wind and traffic loads, through the integration of in-situ monitoring data and the linear fatigue damage rule.
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