Analysis The Reasons And Control Measures Of Cracks Of Long-span PC Continuous Rigid-frame Bridge

Long-span PC continuous rigid-frame bridges have been widely applied during the near thirty years. however, many long-span PC continuous rigid-frame bridges found a lot number of diseases during the construction and using time. In order to solve these diseases of long-span PC continuous rigid-frame bridges, this article explored the reasons of these diseases, ranging from materials, design, construction etc.Then used the finite element method to analysis the reasons,and give preventive measures to the diseases of long-span PC continuous rigid-frame bridges. In this paper, the main research work are carried out as follows:1. based on the Substantial literature we found, Summed up the main diseases of continuous rigid frame-bridge;2. Explore the iMPact of characteristics of cement, coarse aggregate strength on concrete durability,and also the improvement of polypropylene fiber to concrete performance.Give some advice to prevent non-structural cracks in concrete.3. Establishment an local model of a variable cross-sections continuous rigid frame by using the large general-purpose finite element program-ANSYS.CoMParison the iMPact on horizontal tensile stress of cross rib on the bottom of the variable cross-section on the load of the radial force which generated during tenson the prestressed reinforcement on the bottom of the variable cross-section.4.Set up spatial finite element model of the Shui-tu bridge by using the BridgeKF, analyse the spatial effects of the box in the vertical temperature difference and temperature difference between inside and outside of the box. the Box has obvious spatial effect at the Temperature.The spatial effectt of box is Obvious under the temperature difference.the tensile stress on the outside and inside web is obviously fifferent,this is the reason that the inside cracks more than the outside. continuous rigid frame webs are cracks in the inside than the outside one of the reasons.In the same time, The iMPact of temperature gradient play an important role of horizontal tensile stress on the continuous rigid-frame close segment floor. During tenson the second Prestressed reinforcement on the floor of the close segment box. appropriate temperature difference between inside and outside of the box can reduce the horizontal tensile stress on bottom effectively,it have a positive role in prevention disease on the bottom of the close segment box.