Measurement-Based Vehicle Load Model for Urban Expressway Bridges

Bin Chen,Pengzhen Lu,Zheng Zhong,Xu Xie

doi:10.1155/2014/340896

Bin Chen, Pengzhen Lu + Show 2 more

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https://doi.org/10.1155/2014/340896

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Abstract

Significant changes in vehicle loads have occurred in China due to the development of the automobile industry and transportation within the past two decades, particularly the rapid increase in traffic flow and the large-scale emergence of heavy trucks. However, research into vehicle loadings on urban bridges is not well developed. In this study, based on traffic flow data collected using a weigh-in-motion system installed on an expressway in an urban logistics zone, we analyzed the traffic flow, vehicle types, and gross vehicle weight (GVW) features and developed models for the vehicle load and fatigue load. According to the axle space, axle types, and axle number, the trucks in the traffic flow were classified into 10 representative vehicle types. The probability distribution of the GVW was fitted to a three-class mixed log-normal distribution. Using the improved Gumbel method, we determined the extreme value distribution of the vehicle loadings in the purpose reference period and assessed the vehicle loadings of urban bridges. In addition, using the equivalent damage theory, six equivalent vehicle models were established according to the measurements of the axle weight and axle space, thereby obtaining a simplified model of fatigue vehicle loadings on urban expressway bridges.

Highlights

The traffic load is one of the main variables that affect bridges
The traffic load models used in the current standard applied throughout China are based on the analysis of vehicle data collected in 1997 on four national highways during five daytime periods [1]
Compared with the massive volumes of survey data related to highway bridges, the study of urban bridges is very limited in China

Summary

Introduction

The traffic load is one of the main variables that affect bridges. The traffic load models used in the current standard applied throughout China are based on the analysis of vehicle data collected in 1997 on four national highways during five daytime periods (each of 12 hours) [1]. Based on field measurements of vehicles on highway bridges covering six different provinces all over the country, Zhou et al [24] obtained a fatigue load spectrum and the corresponding standard vehicle model for highway bridges using the equivalent fatigue damage theory These traffic surveys were measured mainly by people, rather than machines, which may have entailed unpredictable errors when calculating the axle weight, axle space, and the numbers of vehicles of various types. Based on a dynamic WIM system, the vehicle types and gross vehicle weights were obtained from traffic flow data collected on an urban expressway in a logistics zone, and the improved Gumbel method based on the extreme value theory was used to obtain the extreme value distribution of the vehicle loadings in a specific reference period and the vehicle loadings. Based on measurements of the axle weight and axle space, six equivalent vehicle models were established using the equivalent fatigue damage theory and a simplified fatigue vehicle load model was developed for urban expressway bridges

Urban Expressway Traffic Condition

Probability Model of Vehicle Loads

Fatigue Load Model

Findings

Conclusion