Reconstruction And Expansion Of Existing Highways Research On Service Performance Evaluation And Classified Utilization Technology

Over the past three decades,with the rapid development of China's highway and bridge industry,expressways have played an important supporting role in China's transportation.A problem facing us now is that with the increase of traffic volume and the increase of bridge load levels,the high-speed bridges built under the backward technical level at that time can no longer meet the people's urgent need for a growing high standard of living.Problems such as the reduction of the bearing capacity of existing bridges,the expansion and expansion of old bridges and the reuse of bridges make the evaluation of the service performance of old bridges and how to make full use of them urgent.This article mainly relies on the Beijing-Shanghai Expressway project,supplemented by the results of the reconstruction and expansion of Binlai Expressway and Changyu Expressway,and selects typical bridge structures for the following studies:(1)To this end,this paper carried out the old bridge upper and veneer technical status assessment,indoor and outdoor flexural shear capacity failure test,Abaqus nonlinear finite element simulation analysis of the whole process of stress,beam and plate comprehensive classification and utilization.The main contents and achievements are as follows:(2)First,evaluate the overall and veneer technical status of the bridge respectively,and establish the evaluation index system of the existing beam and slab technical status by means of the appearance technical assessment and the special assessment of durability;separately conduct theoretical calculations based on design specifications and technical status inspection The theoretical calculation and analysis after calculation and correction provide the theoretical basis for the subsequent comparison with the measured limit values.(3)In order to obtain the actual ultimate bearing capacity of beams and slabs,the bearing capacity of existing bridges was evaluated by single-plate load test.For the10 m and 13 m spans of the Beijing-Shanghai Expressway and the 10 m and 16 m spansof the Binlai Expressway,consider the integrated cast-in-situ layer to carry out the indoor and outdoor static load test of the hollow plate flexural and shear capacity.The deflection and strain analysis of the beam and plate bending and shear bearing capacity test results found that the test beam and plate with integrated cast-in-place layer can better meet the current specification requirements.(4)Use Abaqus finite element software to establish a numerical model of the prestressed concrete beam and load it according to displacement.In the process of simulating the static load of the test piece,a plastic damage model is introduced to simulate the damage of the concrete beam;and the damage cloud diagram is obtained.The research results show that the introduced plastic damage model can better show the plastic damage of concrete beams,and the beam load-deflection curve test results are in good agreement.(5)According to the classification principles of "intact equivalent reuse(type A)","reinforced equivalent reuse(type B)","intact reduction function reuse(type C)","abandoned beam and plate(type D)reuse" To establish a classification standard for reuse of existing beams and slabs,and carry out relevant technical research and form a comprehensive utilization technology of existing beams and slabs,to provide technical guidance for the rational use of old bridge slabs for similar bridge expansion and expansion.