Influence Of Overload On Fatigue Behavior Of Orthotropic Steel Bridge Deck

Orthotropic steel bridge deck has many advantages, including high utilization ratio of material, wide usage, large bearing capacity, better riding quality, lower structural height and short construction period, so it is widely used in large-span bridges around the world. However, the orthotropic steel bridge deck is typical thin-wall welded structure, so it is easily to produce fatigue damage under repeatedly function of directly vehicle load. Fatigue crack of orthotropic steel bridge panel happens in China, serious highway bridges overload is an important cause of this problem, it makes the fatigue life of main structure details geometric exponential decline, and greatly accelerated the fatigue damage of steel bridge deck. Therefore, in this paper, the overload effect on fatigue life of orthotropic deck is studied. The main contents are as follows:1. Reviewed the development of orthotropic steel bridge deck, summarize the problem of orthotropic steel bridge deck in European, United States and Japan, especially about the research results of the fatigue load spectrum for highway bridges. Analyzed the problems in direct application of these achievements in China.2. The current design code in China about the situation of the highway bridge fatigue load is not clear, so on the basis of the vehicles model in highway-grade I load, this paper calculates the main structural detail fatigue stress amplitude of common orthotropic steel bridge deck, points out that the normal passage of the vehicle does not cause the main structural detail fatigue damage, overload is the main cause of fatigue crack propagation. Based on the calculation, summarized the bridge design codes of the European, United States and Japan, analyzed and summarized the features of highway overload in different places in our country, listed out the gross load on axle, distance between axle and frequency characteristic value features in different places.3. Three finite element models are established which are different in panel thickness, transverse rib spacing, arc gap of the cross rib and longitudinal dimension, analyzed the force process and stress amplitude of main structural details caused by overloading of vehicles. According to the linear cumulative damage criterion, the equivalent stress amplitude of main structural details under different overload conditions is calculated. According to the obtained stress spectrum the fatigue life of the orthotropic steel deck is analyzed. The failure of different structural forms under different overload conditions is obtained.