Mechanical Behaviors Of Rc Rigid Frame Arch Bridge And Strengthening Techniques For Joints

With the rapid development of national economy, the highway traffic and traffic load increased day by day. Because of this, most bridges were in long-term overload state and appeared various damages with different degree,then this resulted in hidden danger to the safe operation of highway bridges. Among the existing old bridges, the reinforced concrete rigid-frame arch bridge has a strong representation, it has the problem of lacking of capacity, and it has the disease of the cracking of the major or minor node. Because of the rigid-frame arch bridge has the advantages of lightness, beautiful appearance and low cost etc, it is necessary to study on damage mechanism and mechanical properties of rigid-frame arch bridge. Combining with research program of Shandong natural science fund'study on the mechanical mechanism and optimization design of strengthened reinforced concrete rigid-frame arch bridge' (Y2007F58), the major theoretical and research contents are mainly summarized as follows:(1)Based on the rigid-frame arch bridge standard drawings of 25m,35m,45m and 60m, using the finite element analysis software, establish the whole modeling of four rigid-frame arch bridges to study the transverse load distribution coefficient and transverse distribution coefficient along the longitudinal.The results show that, the transverse load distribution coefficient calculated by elastic supported continuous beam method is smaller, and the span smaller, the errors bigger.(2) Considering five kinds of vehicle load level in the new and old standard, using finite element software, systematically study on the influence of mechanical properties of different load level to rigid-frame arch bridge by using the whole space analysis and graphic analysis method. The results show that, the internal force calculation result is different by different analysis methods for every sections of rigid-frame arch bridge. The moment of mid-span calculated by graphic analysis method is smaller than whole space analysis, but the negative moment of arch feet is bigger.(3)Reduction the rib distance of existing 35m rigid-frame arch bridge by 0.8 times, study on mechanical properties of rigid-frame arch bridge spacing by reduction the rib distance. The results show that, after the rib distance reduction, the transverse load distribution coefficient is close to the value calculated by elastic supported continuous beam method, and force and deflection are reduced largely.(4) Using finite element analysis, systematically study on the mechanical properties of different span bridges under overweight transportation by the five axles trucks (55t) selected to be standard vehicular modes.The results show that, the force and deflection has greatly increased under the overweight vehicle loading.(5) Study on the cracking mechanism of major or minor node of rigid frame arch bridge by the five axles trucks (55t) selected to be standard vehicular modes.Based on it, give a strengthen node technology by embedded steel plate, and analyze the stress by the factors of steel plate number, thickness and hollow rate etc.