Research On Behavior Of Smart Concrete Girder Bridge With The Hydration Heat Temperature Effect

With the excellent character such as good integrality, large span, lighter weight, attractive appearance, prestressed reinforced concrete girder bridge have been widely used in the construction of bridge engineering, and develops gradually towards the direction of large span and large cross-section. It has already into the category of mass concrete on the size effect.The existing research data show that many factors such as environmental conditions and overload can aggravate the development of the deflection and cracks of the bridge structure and make steel exposed to the environment, thus exacerbate the corrosion of reinforcement.As is known to all, steel corrosion seriously affects its mechanical properties, causes the concrete cover fall off, reduces the ductility and bearing capacity of the structure, which will pose a threat to the safety and service life of the structure. Especially for the marine environment bridge, influenced by humid air and chloride ions, the crack prevention has become a top priority of the bridge project.Shape memory alloy(SMA) has gradually been used in civil engineering fields because of its unique shape memory effect. When the temperature of SMA rises, the restoring force up to400 MPa ~ 600 MPa can be produced because of the material deformation. The present study has applied SMA to the concrete girder bridge successfully, realized the intelligent control of the structure. But when the restoring force of SMA is excited, it is usually heated by electricity, which is difficult to be realized in engineering due to the limitation of construction conditions. In this paper, the SMA strand was put on the bottom plate of concrete girder bridge, then exploited the temperature effect of concrete hydration heat to stimulate SMA deformation, and applied the restoring force on structures to control its evolution of crack and deflection, thus achieved an ideal effect that improving the durability and safety of structure.In summary, several aspects of work were made as follows:(1)Theory research and finite element analysis of temperature and stress fields were made about a certain concrete box beam. Verified the correctness of ANSYS finite element program in box girder temperature effect analysis, and elaborated the temperature and stress field of box girder and cracking mechanism of the web temperature cracks.(2)With the temperature field finite element research of one single-span prestressed hollow slab girder bridge, analyzed the temperature values of SMA arrangement places.Combined with the existing experimental research results, calculated the value of restoring force and the required prestrain exerted when phase transition of SMA was stimulated by this temperature.(3)Researched on the performance of a smart concrete girder bridge based on the ideology of thermal-mechanical coupling. The finite element analysis was conducted about its carrying capacity and the variation of crack and deflection under vehicle load before and after the SMA strand embed respectively. The results showed that the restoring force stimulated by the hydration heat has a significant inhibitory effect on crack and middle span deflection of concrete beam bridge, and the structural durability is improved obviously.