Study On The Mechanical Properties Of The Wet Joint Of The Simply Supported Continuous Beam Bridge Under Complex Constraints

At present,simply-supported continuous bridges are widely used.The simple-supported to continuous bridge has good spanning ability and smooth and comfortable operation conditions,which well meet the engineering requirements.At the same time,in the engineering practice,it is found that the post cast wet joint is the weak part of the simple support to continuous bridge,which is easy to be damaged.Therefore,further research on the simple support to continuous post cast wet joint has certain engineering value.In this paper,the development of simply supported to continuous bridge and the engineering characteristics of each period are briefly summarized,and then the relevant research at home and abroad is analyzed.Then it introduces the relevant engineering background,construction technology and details the research content and innovation of this paper.In this paper,Midas model is used to simulate the single-piece small box girder structure and analyze the deformation of the structure under different construction stages and temperature loads.The hydration heat model of MIDAS wet joint is established,and the hydration heat release of early concrete is studied theoretically.In this paper,the temperature and strain of the key joints are analyzed through the in-situ test of the wet joint,and the temperature and deformation of the wet joint in the actual project are summarized and analyzed.The internal forces caused by different national gradient codes are summarized and compared with the measured temperature gradient.Finally,the refined finite element model of ABAQUS wet joint is established,and the deformation law of the wet joint under different working conditions and various factors is studied in detail.Firstly,combined with Midas model,the stress and deformation of the wet joint under different construction conditions are analyzed.The results show that the wet joint is safe under different conditions.The results show that the larger negative bending moment will cause the larger tensile stress in the lower part of the wet joint,which is easy to be damaged.For wet joints,it is recommended to use concrete with small expansion rate.Under thermal coupling,the lower part of the wet joint has a large constraint and a small deformation,which will produce a large stress concentration and lead to failure.