Statistics and Cause Analysis on Diaphragm Cracks of Long-span Continuous Beam Bridge
Taking a long-span concrete continuous beam bridge as the engineering background,the causes of cracks in the mid-span diaphragm are explored.The cracks in the mid-span diaphragm are detected and counted.The single-span solid model is established by ABAQUS to analyze the influence of various factors.Based on the field measured data and the standard loading temperature load,the main influencing factors of the crack formation of the mid-span diaphragm are analyzed combing with the crack detection.The result shows that(1)There are many tiny cracks in-span diaphragm concrete during self-hydration shrinkage after pouring.After pouring to the concrete age of 14 d,the mid-span diaphragm begins to crack from both sides of the manhole.With the increase of age,the number of cracks increases and gradually expands to the manhole and the roof.At the age of 14 d,cracks and expansion have been basically formed.When the age is 28 d,the cracks expand slightly and the overall distribution is basically the same as that of 14 d.(2)Cracking of mid-span diaphragm is different under 3 kinds of temperature loading.Cracks caused by roof temperature rise extend from manhole to roof.The cracks caused by the overall temperature drop are mainly located between the manhole and the web,and the overall expansion is along the vertical direction.Cracks caused by overall temperature rise are mainly located near roof and manhole.(3)Local maximum tensile stress of mid-span diaphragm under partial load is 2.18 MPa,which is not enough to induce diaphragm cracking,however,under the combined action of other factors,the diaphragm will cause crack propagation in the case of micro cracks.The angle between the expansion direction and horizontal direction is about 45°.The crack propagation trend of finite element simulation is basically consistent with the actual detection.The study result can provide reference for similar engineering design and construction.
bridge engineeringanalysis on crack causesfinite element analysismid-span diaphragmcontinuous beam bridge
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