ANN and LEFM-Based Fatigue Reliability Analysis and Truck Weight Limits of Steel Bridges after Crack Detection

Lei Nie,Lu Deng,Wei He,Wei Wang

doi:10.3390/s22041580

Abstract

Fatigue of steel bridges is a major concern for bridge engineers. Previous fatigue-based weight-limiting method of steel bridges is founded on the Palmgren–Miner’s rule and S-N curves, which overlook the effect of existing cracks on the fatigue life of in-service steel bridges. In the present study, based on the theory of linear elastic fracture mechanics, a framework combining the artificial neural networks and Monte Carlo simulations is proposed to analyze the fatigue reliability of steel bridges with the effects of cracks and truck weight limits considered. Using the framework, a new method of setting the gross vehicle weight limit for in-service steel bridges with cracks is proposed. The influences of four key parameters, including the average daily truck traffic, the gross vehicle weight limit, the violation rate, and the detected crack size, on the fatigue reliability of a steel bridge are analyzed quantitatively with the new framework. Results show that the suggested framework can enhance the fatigue reliability assessment process in terms of accuracy and efficiency. The method of setting gross vehicle weight limits can effectively control the fatigue failure probability to be within 2.3% according to the desired remaining service time and the detected crack size.

Highlights

IntroductionAn increasing number of steel bridges are suffering from fatigue cracks under the action of cyclic heavy trucks, which may threaten the safety of bridges
Fatigue of steel bridges has always been one of the major concerns of bridge engineers.An increasing number of steel bridges are suffering from fatigue cracks under the action of cyclic heavy trucks, which may threaten the safety of bridges
Very few previous studies investigated the influences of the gross vehicle weight limit (GVWL) on the fatigue failure probability of in-service steel bridges with cracks

Summary

Introduction

An increasing number of steel bridges are suffering from fatigue cracks under the action of cyclic heavy trucks, which may threaten the safety of bridges. It is urgent and significant to research the fatigue problem of steel bridges under overloaded truck traffic and take reasonable measures for vehicle weight limits. The traditional idea for vehicle weight limits is checking and comparing the value of the stress induced by the overloaded truck with that induced by the design load [1]. Many countries or regions have issued corresponding regulations to check whether a truck is permitted to cross a bridge. The Bridge Formula B is widely applied in the United States to judge whether a heavy vehicle can cross a bridge [2].

Methods

Results

Conclusion