Research On Mechanical Analysis Of Continuous Beam-Arch Composite Bridge

The presence of the continuous beam and arch combination bridge,which is a new system of bridge structure,brings the weight advantage of the arch and beam into full play,showing a better,more economical and beautiful form.Beam and arch composite bridge has a greater competitive advantage in the 60m~200m span range.Therefore,research on the stress features is extremely important.Taking the sand river bridge as the engineering background,the research and analysis of the mechanical characteristics of the continuous beam arch combination bridge is carried out in this paper.(1)Establishing a calculation model of continuous beam arch combination bridge at arch rib construction stage and explaining the difficulties on the establishment of structure of the model unit and the simulation of construction stages.Setting pre arch through calculating and analyzing and monitoring the arch rib alignment and stress,and then the measured data and the theoretical data are compared and analyzed.The corresponding correction is done in the construction process,making the arch rib construction finished meets the design requirements.(2)The span ratio is an important design parameter of arch bridge.Three different span rations,including “f_z/l_z=1/6 and f_b/l_b=1/5”、“f_z/l_z=1/5 and f_b/l_b=1/5”、“f_z/l_z=1/5 and f_b/l_b=1/4” are selected to analyze the stress characterizes of continuous beam arch composite bridge in constant load and live load.Stiffness ratio is also the important design parameter,especially for the continuous beam arch combination bridge,the arch rib and the girder stiffness ratio have a lager influence on the structure internal force.Based on the original design stiffness,the paper separately changes the main beam stiffness into 90% and 80% of design stiffness and analyzes the influence on force characteristics caused by the girder stiffness changes of continuous beam arch composite bridge under constant load and live load.Through continuous beam arch combination bridge vector span ratio and stiffness ratio parameter design research analysis,the influence characteristics on structure stress caused by different rise span ratio and stiffness ratio of structure are summarized,providing certain guiding significance for similar bridge design.(3)The continuous beam arch composite bridge’s variation characteristics of internal force and deflection of structure in the process of designing the hanger are calculated and analyzed by using formal analysis method.The hunger tension is designed according to the actual construction and optimization objective and three different hangers tensioning schemes are chosen.After comparing the influences on structure internal force and deflection during the tension process,the optimum scheme is determined to guide the construction of the site according to the optimization objective.(4)The commonly used methods for The Suspender Force Test are introduced and the advantages and disadvantages and the application fields are analyzed.Spectrum analysis method is determined as Suspender Force Test method,the influence factors are summarized,and the focus is discussing the suspender calculation length value problem.For short boom,theoretical calculation length is not suitable for the calculation of the length of the suspension force test,and it is best to use the measured correction method for its measurement and calculation.