Mechanical Performance Analysis Of Open Spandrel Rigid-Framed Arch Bridge

Open spandrel rigid-framed arch bridge is the development of traditional rigid-framed arch bridge during its application in China. It utilizes and develops the mechanical performances and advantages of arch and rigid-frame. Through the finite element method, this paper compares some variable parameters such as the arch axis, the rise-span ratio and the ratio of spans, which influence the mechanical performances of open spandrel rigid-framed arch bridge.Then it summarizes the mechanical properties of this bridge type and the optimal range of these parameters. The plexiglass model test validates the correctness of the finite element method used in this paper. The study will provide reference for the design of this new bridge type. The conclusions are list as follows:(1) The mechanical properties of different parts of the bridge are as follows: arch is under the combined action of compression and bend; open spandrel beam is under the combined action of tension and bend; close spandrel beam is under the combined action of compression(or tension) and bend , but the axis force is small.(2) The common used arch axes are circular arcru parabola arch, catenary arch. Circular arch is rational for big rise-span ratio, but each has his strong point for small rise-span ratio.(3) The common used rise-span ratios are 1/6-1/12. By the decrease of rise-span ratio, the internal forces are increasing linearly except of the moment of open spandrel beam.(4) The ratio of spans is 0.5-0.7 commonly. The axis force and moment of critical section are decrease linearly by the increment of the ratio of spans.(5 ) For segmental bridge, creep will cause secondary force because of changing of the system. Creep has slight influence on the distribution of internal force of rigid-frame, but has great influence on the spandrel beam.(6) The mechanical performance of min Jiang bridge is reviewed through the plexiglass model test. The compare of the results of the model test and the finite element analysis validates the correctness of the finite element method used in this paper.