Dissertation > Excellent graduate degree dissertation topics show

Crack Study and Local Fatigue Analysis of Orthotropic Steel Decks on Bridges

Author: ZhouZuoBin
Tutor: PanPeng
School: Tsinghua University
Course: Civil Engineering
Keywords: Fatigue crack Local fatigue Monta Carlo method Rainflow Equivalent number of cycles
CLC: U443.33
Type: Master's thesis
Year: 2010
Downloads: 193
Quote: 1
Read: Download Dissertation

Abstract

In recent years, with the increasing road traffic flow, highway bridge fatigue problem becomes more and more significant. To this end, the highway bridge fatigue problems at home and abroad has been carried out extensive research and the formation of the relevant norms. However, for the study of the local fatigue problems of the steel deck, there are still insufficient. A southern highway bridge steel box girder put into use a decade or so there has been fatigue cracks, a serious impact on the safety and performance of the bridge structure, causing widespread concern in society. Firstly, for the causes of the bridge steel box girder cracks were analyzed. Bridge cracks a detailed investigation; vehicles on the bridge load statistics, especially overloading of heavy vehicles; establish the finite element model of the bridge to the mechanical properties, the stress distribution of the bridge deck, and discuss the impact of stress concentration and the welding residual stress. Analysis, the following conclusions: (1) The Bridge cracks, the cracks in the bridge deck is the most serious. (2) the actual traffic load is much higher than the original design load. (3) U ribs and bridge deck connections have a greater cross-bridge to stress, especially vehicle load acting on the diaphragm position, there is a significant stress concentration. U rib bridge deck connections, as well as U ribs and diaphragm connections, and have a greater welding residual stress. Secondly, the paper of the bridge, for example, proposed a method of analysis to assess local fatigue. Load their vehicles in the past 11 years for statistical analysis, the probability model vehicle loads and Monta Carlo method to simulate the bridge deck partial load history analysis to calculate the equivalent fatigue loads and the corresponding equivalent number of cycles. During the simulation takes into account the uncertainty of the vehicle load, vehicle load partial reduction factor to consider the impact of the the wheel lateral position of the local stress. The simulation results show that: This paper analyzes the results of the equivalent number of cycles in the AASHTO specification fatigue damage fatigue stress cycles within a reasonable range, the current state of fatigue cracks in the Bridge. Finally, as the research object embedded complement segment of the bridge U rib, local fatigue analysis. According to the results of the probabilistic model of the vehicle load and finite element calculation, Monta Carlo simulation to go out lane U ribs embedded the complement segment of stress, with Rainflow statistics stress cycle analysis to calculate the equivalent fatigue stress amplitude and the corresponding Validity cycles. The simulation results show that: This paper analyzes the results of an equivalent number of cycles is much smaller than the AASHTO specification fatigue failure fatigue stress cycles, U rib patch to crack and the bridge does not match the status quo.

Related Dissertations

CLC: > Transportation > Road transport > Bridges and Culverts > Bridges constructed > Superstructure > Bridge deck pavement
© 2012 www.DissertationTopic.Net Mobile