Study On The Residual Life Of Hollow Beam With Small Span In Expressway Reconstruction And Expansion

China's expressway began in the late 1980 s,because of the economic level and technical level,there are many deficiencies in the construction of the expressway,operation and maintenance.In recent decades,with the rapid development of the national economic level,the traffic volume has been increasing continuously,which led to the early construction of highway bridges to bear much more vehicle loads and to the accumulation of structural damage.Under repeated vehicle loads,although the stress of bridge components is far below the yield strength limit,it is easy to damage the bridge,and the bridge life is much shorter than the designed life.Therefore,whether the bearing capacity of the old bridge in the reconstruction and expansion of the expressway can meet the load standard after the reconstruction and expansion,and how much is the remaining life of the old bridge after the removal of the beam plate,and whether the old bridge can meet the standard requirements after the reconstruction and expansion of the expressway,it is an important problem to be solved urgently for high-speed reconstruction and expansion.Based on the changyu high-speed reconstruction and expansion project,this paper carries out theoretical analysis and experimental research on the residual bearing capacity and fatigue life of old bridge hollow slab,and accurately evaluates the residual bearing capacity and fatigue life of old bridge slab.The main research work of this paper is as follows:(1)carry out a survey on the technical status of existing bridge girder plates.Through analyzing the influencing factors of the technical status of girder plates,determine the key testing indicators of the technical status of girder plates,clarify the deduction criteria for testing indicators,and put forward a rapid evaluation system for the technical status of old bridge plates.(2)carry out technical evaluation and classification of existing Bridges,select representative members of various Bridges for static load test,and establish a calculation formula for the residual bearing capacity of beams and plates based on technical conditions through the comparison and analysis of static load test results and theoretical calculation.(3)through the analysis of the factors affecting the durability of the beam and plate,the key testing indicators of the durability of the beam and plate are determined,and themarking deduction criteria of the testing indicators are clarified.The durability evaluation system of the old bridge plate is proposed to provide a scientific basis for the comprehensive evaluation of the durability of the dismantled beam and plate.(4)considering the durability of beam slab,select 10 meters beam slab continuous fatigue load test,through fatigue experiment both beam slab cycles and the corresponding stress amplitude,considering the durability of beam slab,to reduction of beam slab cycles,and USES the least squares regression fitting analysis was carried out on the s-n curve,based on the durability of the status of the fatigue life calculation formula,the accurate evaluation of beam slab remaining fatigue life.