A large number of 40 m precast concrete simply supported box girders are used in the construction of high speed railway bridges in China.In order to study the influence of cracks on the mechanical properties of the structure,a static load test was carried out on a 40 m simply supported girder with cracks.The results show that under the design bending moment,the concrete at the crack position still maintains the elastic working state.The roof cracks do not have an adverse effect on the mechanical performance of the girder,but they can affect the durability of the structure,and the cracks should be sealed.The transition of a simply supported girder from a simply supported girder storage state to a cantilever girder storage state can cause concrete cracking in the girder roof.During the construction phase of prefabricated box girder,attention should be paid to observing the settlement of the girder storage pedestal.
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