Based On The Cracking Characteristics Of Statistical Parameter Of Box Girder Bridge Safety Evaluation

In the current one of the most common bridges is prestressed concrete box girder bridge, under the influence of the effects of external load repeated effect and the lost of main girder steel prestress factor and so on, main girder will appears different degree of cracking and deflection diseases. So regularly inspection for bridge appearance has become a necessary precondition for maintenance of bridge reinforcement. Characteristics of girder crack parameters is also one of the important indicators of statistics. How to through visual inspection of bridge that crack characteristics parameters to evaluate security is an important practical significance of the bridge operation stage of the statistical value, at the same time, the main idea and direction is studied in this paper.In this paper, the main reasons of prestressed concrete box girder bridge girder cracking due to the longitudinal teel loss of prestressed, with the calculation method of the height of the section of compression zone curved beam section after cracking as the ideological basis, through the statistics of the cracking of box girder bottom transverse crack characteristics parameters,derives the formula for calculating the cracking of box girder cross-section eigenvalue.Through between prestressed strands and concrete due to the strain resulting from the interaction of difference into account,then calculate the average prestress of the cracked section of the same level,and approximate as effective prestressed. Through the longitudinal steel beam prestressed put forward the actual distribution prediction methods, and simplify the predicting method, applicate it in the box beam bridge of post cracking, and the feasibility of this method is verified by an example.The characteristic parameters of crack through visual inspection of the real bridge in operation in a statistical, use of simulation and prediction method of the above, adjust the parameter value of the prestressed strand to simulate and predict the bridge operation state,through the comparison of the situation analysis of the different operation time main beam stress and deflection value to evaluate the safety of the bridge, and proposed some reinforcement and maintenance measures.