Mechanical Performance Analysis Of Special-style Beam-arch Composite Bridge During Construction And Operation

The special-style beam-arch composite bridge with a beautiful shape,which are the advantages of ordinary arch bridge and traditional bridge.Because of its complex structure,the difficult of mutual reference and the characteristic of space indeterminate structure,structural behavior and stress characteristics are not easy to grasp.The safety of the bridge structure in the construction process and operation condition is very difficult to be directly evaluated according to mechanical laws of conventional bridge,so it is necessary to build the corresponding finite element model for concrete bridge.Based on the Qiancheng road bridge in Zhengdong New District in Zhengzhou City,the paper analyzes the model of the whole Bridge during Construction and Operation in finite element method,then masters some mechanical properties of the composite arch bridge according to the calculation results.The main research contents and conclusions are as follows:(1)Through the introduction of the classification and stress characteristics of arch combination bridge,based on collecting related information at home and abroad and a brief summary of the research results,the mechanical behavior and stress characteristics of the special-style composite arch bridge are summarized.(2)Introducing in detail the main structure and the design standard of the Qiancheng road bridge in Zhengdong New District,in this context,the spatial finite element models are built by software MIDAS/Fea and MIDAS/Civil,and the simulation process is explained.(3)The influence matrix method is applied to adjust the suspender internal force in finished bridge state,and concluded that the suspender tension of the composite arch bridge in the reasonable finished state.On the basis of the analysis of the stress and deformation of the main elements of the bridge,the mechanism of transferring the internal force of the Qiancheng road bridge is obtained that the suspenders transfer most dead load of the main steel girders to the arch ribs,then the load is transferred to the V pier rigid frame along arch axis in the form of axial pressure,finally,the statically indeterminate V pier rigid structure will pass it to the foundation.(4)This paper divides the construction process of the Qiancheng road bridge by bracket method into 21 stages.Through analyzing the characteristics of stress and deformation of the main components of the bridge,it's conclusion that after the completion of the V pier rigid structure and the formation of the statically indeterminate structure,the subsequent construction has little influence on the maximum compressive stress and deformation of concrete members,and the inclined legs of the V pier and the upper box girders are always under compression;the stress and deformation of the steel arch ribs are more obvious than the steel main stringers and the small beams in the medium span,and in the most unfavorable conditions,its strength and rigidity can meet the requirement of the specification for steel structures;the maximum internal force of the suspenders is not all in the finished bridge state,and some of the most unfavorable conditions are the stage of the completion of the pavement,the safety factor of each suspenders in the construction can satisfies the specification.(5)Through the analysis of live load and temperature load in operation stage,it's conclusion that live load is a weak influence on the stress and deformation of the bridge,while the temperature load has a significant impact on it;under the most unfavorable live load,the internal force of suspenders is about 24% of it in the finished bridge state,and the temperature load only has a great influence on a few suspenders near the arch foot,when the rise and fall of the whole structure temperature,it's easy to appear large tensile or compressive stress in the concrete structure,and the internal temperature stress in the steel structure is very small;the influence of gradient temperature load on the overall performance of the bridge is between the live load and the global temperature load.(6)The ultimate limit state and serviceability limit state of the bridge structure are checked to meet the requirements of the code,and the design is reliable.