The Research On Concrete Fatigue Mechanism Of Prestressed Concrete Box Girder Webs Anti-Crake

The automobile loading of modern transportation shows protracted nature and channelization which has the repeated load characteristics and the incline cracks of many prestressed concrete continuous box girder bridges in service period have made bridge researcher to considering fatigue assessment of prestressed concrete component. Based on this premise, the paper mainly does the following:(1)The paper refer to the relative literatures, introduces the fatigue properties of concrete research at home and abroad and the concrete strength theory, knows the main achievements about concrete fatigue research in the past and research points at now and the trend in the future through learning the fatigue research and strength theory of concrete, which provides the relevant theoretical support for the subsequent research work.(2) It learns the differences about fatigue assessment of concrete in all codes through checking the codes in some countries, which include the fatigue assessment in our nations is that controlling the fatigue stress through adopting uniaxial strength criterion in static load condition and adopting the S-N curve equation of cycle load to control the fatigue stress in foreign codes. It gets the corresponding conclusions that calculates and compares the actual example through using the ways mentioned in the codes.(3) Based on less provisions of fatigue assessment of inclined section involved in the codes, the paper proposes a thought of fatigue assessment of inclined section of prestressed concrete. It draws the fatigue value envelope on the bis-axis strength destroyed envelope of concrete and related S-N fatigue curve equation mentioned in foreign codes, and then gives the values of inclined section fatigue assessment.(4) Finally, it verifies rationality of the values that calculates and compares some continuous rigid frame bridges according to the two ways mentioned in our nation code and inequality given in the paper, and it provides some references for a follow-up study of fatigue assessment of prestressed concrete continuous box girder inclined section.