| Prestressed Concrete(PC)continuous rigid frame bridges are widely used in bridge engineering because of their high structural stiffness,good smoothness and low cost.However,in recent years,severe deflection problems have occurred in the service of PC bridges,which will not only reduce the aestheti cs of the bridge structure,but also reduce the safety performance of the bridge,limiting the further application of PC bridges in engineering.Therefore,the research on the causes of deflection,deflection risk assessment and re inforcement strategy of continuous rigid frame bridges is important to ensure the safety and durability of bridges in service.In this paper,a large span PC continuous rigid bridge in Guangzhou is used as the basis of the project,and a combination of field inspection,numerical simulation and theoretical analysis is used to study the causes of deflection and re-inforcement strategy of continuous rigid bridge.By analyzing 22 years of measured deflection data of a large-span PC continuous rigid frame bridge in Guangzhou,and combining the results of field inspection and existing research reports,the loss conditions of each factor are gradually considered in finite elements.The causes of deflection in large span PC continuous rigid frame bridges were analyzed and a finite element model considering the damage condition was established to provide basic data and verification basis for the subsequent analysis(Chapter 2).Based on the conclusions of the causes of deflection in Chapter 2,a sensitivity analysis of the relevant factors is carried out to determine the main factors causing the deflection in the span.Based on the main influencing factors,a multiple regression analysis was implemented in combination with Python,and a response surface model was constructed by training 30 sets of data,and the validity of the model was verified.The model was also modified based on the actual measurement data.(Chapter 3)A risk assessment matrix was established,and the risk condition of the bridge during the operation period was evaluated and predicted.The risk assessment matrix was constructed based on the minimum reasonably practicable criterion and the relevant bridge technical evaluation criteria,considering the risk damage probability and the risk failure probability.Combined with the revised response surface model,a Python risk assessment script file was constructed,and the bridge risk status during the operation period was assessed and predicted.(Chapter 3)Based on the damage finite element model established in Chapter 2,the stress performance of the structure during the operation period was studied and the damage control index was determined.Combined with the sensitivity analysis results and risk assessment conclusions in Chapter 3,targeted strengthening solutions were proposed: 1)Based on the original base plate external beam,a full-bridge external through-length beam plus pivot point apex short beam configuration scheme was proposed,and the reasonable arrangement of anchorage points and steering points of the through-length beam and apex short beam were investigated,and the strengthening performance and strengthening effect of the strengthened bridge were analyzed and evaluated.2)A short tower diagrid strengthening scheme was proposed,and the reasonable values of two parameters,namely the length of the cable-free zone and the height of the tower,were studied in the light of the actual situation of the bridge,and the force performance and strengthening effect of the strengthened bridge were analyzed and evaluated.The calculation and analysis show that both strengthening schemes can effectively improve the girder alignment and structural stress state,which can provide a basis for the design of actual strengthening projects.(Chapter 4)... |
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