Study On Reinforced Prestressed Concrete T-Shaped Beam Bridge With Section Changing Method

Because of its many advantages,prestressed T-beam bridges are currently widely used in the construction of domestic high-grade highways.However,with the increase in the number of years of operation,early construction of prestressed T-beam bridges caused a number of structural diseases due to the influence of the natural environment,unreasonable local design,construction process conditions,and other reasons,such as excessive cross-middle deflection,cracking.Wait.The large number of prestressed T-beam bridges and their large number of bases are widely used in China’s highways and railways.Once a safety hazard arises,it will have incalculable consequences.If these prestressed T-beam bridges are dismantled and rebuilt,they will not only be laborious,time-consuming and cost-consuming,but will also interrupt traffic for a long period of time,causing huge waste of social resources and greatly affecting regional economic development.Therefore,a reasonable and effective reinforcement method is explored for each factor that causes the damage of prefabricated prestressed T-beam bridges,and a safe,economical and applicable prestressed T-beam bridge is reinforced by practical reinforcement without interruption of traffic.Technology,in order to quickly and efficiently improve the bearing capacity and durability of prestressed T-beam bridges,has important social and economic significance.This paper proposes a section transformation to enhance prestressed T-beam bridge technology and carry out related research.The main research contents include:(1)The main mechanism of the conversion of the prestressed T-beam bridge section is illustrated,focusing on the mechanical properties of the box-section and the working mechanism of the anchorage-barrier system.(2)The stress calculation methods for concrete beams and prestressed steel beams of main girders during the construction period of prestressed T-beam bridges with section conversion are deduced.The formulas for bearing capacity of normal section bending resistance,oblique section shear resistance and oblique section bending resistance are deduced,and the cross section is revealed.Conversion reinforcement reinforcement technology mechanics.Through the formula analysis and comparison,it can be seen that the stress state of the prestressed T-beam can be improved after the cross-section conversion is enhanced,and the bearing capacity of the cross-section can be significantly improved.(3)Based on Abaqus platform and Midas Civil platform to carry out refined numerical simulation analysis,summarizing the transformation of the stress and deflection of the pre-stressed T beam,new floor and other components before and after the cross-section conversion enhancement.The results show that the cross-section conversion enhancement technology can effectively improve the stress state of the prestressed T-beam,reduce the deflection of the main beam,and significantly increase the bearing capacity of the section.(4)Key parameters of the pre-stressed T-beam bridge technology with section transformation are analyzed,and the reinforcement ratio of the new floor,the reasonable range of value of the reinforced section and the proposed value are given.A section-conversion reinforced prestressed T-beam is proposed.The rational construction process,construction process and construction precautions of the bridge provide technical references for the successful implementation of the reinforcement technology.(5)In order to verify the enhanced effect of the prefabricated T-beam bridge technology with cross-section conversion,a scaled model test was conducted.The test results show that the newly added baseplate can co-operate with the original structure after reinforcement of the cross-section conversion,and the steel bars between the inter-and inter-beam reinforcements are horizontal.The distribution layer accords with the objective lag effect distribution and constitutes the mechanics of the box-section beam;after the reinforcement,the strain and deflection values of the model beam decrease under the same load;after the reinforcement,the cracking of the main beam lags behind,and the crack indicators are reduced before the reinforcement.The mechanical state of the main beam is improved;after the reinforcement,the torsional stiffness of the model beam is increased by 3.5 times and the carrying capacity is increased by 28%.The research results of this dissertation can provide a theoretical and experimental basis for the application of cross-section conversion and prestressed T-beam bridge technology.