Study On The Performance Of Reinforced Concrete Beam Bridges For Medium And Small Span Highways

With the rapid development of China's economy,the traffic volume has grown rapidly.The four-lane expressway built in the early stage can no longer meet the needs,so it needs to be expanded and rebuilt.Taking the simple span hollow slab and T beam as the example,the Midas/civil finite element software and the beam lattice method are used to analyze the on-board load effect of the bridge structure after widening,the influence of different joint stiffness on the internal force of the new and old bridges,and the concrete shrinkage.The effect of creep variation and the difference of foundation settlement.Firstly,under the influence of vehicle load,the old and new bridge structures have a good synergistic force.After the new and old bridges are spliced into a whole structure,the overall stiffness of the structure increases,and the new bridge can share the vehicle load for the old bridge.Secondly,the lateral distribution of the bridge structure and the internal forces of the new and old main beams under different joint stiffness are calculated and analyzed.The results show that the lateral distribution coefficient of the new and old main beams can be reduced after widening,and the splicing.stiffness can be increased to reduce the old bridge.Internal force effectively improves the overall performance of new and old bridges.Then,analyze the effect of concrete shrinkage and creep on the internal forces and displacements of the new and old main beams.The calculation results show that with the increase of the splicing time,the internal force and displacement of the main beam are basically reduced,and the joint stress is increased.Therefore,the recommended time for splicing and splicing time of the hollow slab bridge is 90 days to 180 days.It is 90 days to 360 days.Finally,the influence of the difference in foundation settlement on the widened structure and the influence of the joints are analyzed.The differential settlement has a great influence on the internal force of the main beam on both sides of the joint of the new and old main beams,and the joint is the most unfavorable influence on the bearing position.It is calculated that the allowable relative settlement difference of the hollow slab beam should not exceed 3 mm.The hinged,rigidly connected,and just connected +3 diaphragms between the new and old bridges of the simply supported T-beams should not allow the relative settlement difference to exceed 4 mm;the new and old T-beams Just before the +5 piece diaphragm connection allows the relative settlement difference should not exceed 3mm.