Roll Stability And Seismic Response Of Reinforced Concrete Rib Arch Bridge Analysis

Although reinforced concrete (RC) arch bridge isn't a new bridge type, it is often used in case of medium-span and mini-type arch bridges. A large numbers of reinforced concrete arch bridges have been built in our country from last century. The stability is important for the health of these arch bridges. To do some analysis on the design factors' effect and the weakness points' influence has practical significance. The researches on the arch bridge with radial loads have been carried out, but the calculating model of radial loads is not suitable for most arch bridges because of the vertical loads being used frequently. The lateral buckling calculation for the parabola arch bridge was used to in trial way. Sometimes the vertical loads are simulated as the radial loads for arch bridges, which couldn't get the exact results. Now, with more and more new material and technology being applied in the civil engineering, it is necessary to build a simplified and practical methodology to calculate the lateral buckling loads of the arch bridge and to pay enough attention to some weakness points. Based on these, the following four parts has been emphatically done along with the Yingnahe Bridge detecting project in this paper.1. The basic equation of flexual deformation of circle arch bridge is summarized. The formula for critical loads of lateral bucking arch bridge is calculated both in the situation of hinged bearing and built-in joint. In addition, the effect of non-direction force is considered.2. Through the analysis of the parabola parallel double-rib arch bridge with vertical loads, some important parameter such as the arrow-span ratio and the lateral flexural and torsion rigidity of arch ribs and the lateral flexural rigidity and number of lateral bracing is discussed. The figures are drew to show the sensitivity of critical loads by different parameter. The effect of boundary is also considered. In addition the non-direction force effect is well calculated.3. With ANSYS program, a comprehensive analysis is carried out for the lateral stability of Yingnahe bridge. The critical loads' formula previously concluded in the 3rdpart is checked. To check the lateral buckling modes the bridge's ANSYS model is improved into certain cases. In these cases certain parameters are changed and the buckling modes are calculated. The outstanding cases are picked out and constructive advices are offered to enhance the lateral stability of Yingnahe bridge.4. Seismic time-history analysis is done for Yingnahe bridge using the Northridge earthquake records. The response of key sections and key points is also obtained. For further study, the size and elastic modulus of certain key section are change regularly. 36 cases are performed and the possible damages are simulated. By the analysis of each case's earthquake response, the critical one is chosen out. Valuable proposals has been made for the health of Yingnahe bridge. Such potential dangers should be avoided during the service period.In conclusion, this paper perfects the theory of lateral buckling of parabola arch bridge. It only needs the main rib and lateral bracings' lateral flexural and torsion rigidity,the arrow-span ratio and other parameter to calculated the lateral buckling factor. So it will save some time to build a complex finite element model. With the above analysis, design factors' effects on the stability of arch bridges are full materialized. Through the example of Yingnahe bridge' finite element analysis, the theory is examined and the difference is acceptable. By the discussion of adjusted bridge's earthquake response in different cases, the possible damages are simulated. Thus some constructive suggestions for the health of the reinforced concrete arch bridge are offered.