Theoretical And Experimental Study On Out Of Plane Instability Of Parabolic Fixed Arch Under Concentrated Force Of Arch Crown

With the development of China's economic construction,the construction and civil engineering industry has been fully developed,and long-span bridges have become more and more common.As a common arch bridge,parabolic arch bridge has attracted more and more attention in recent years.In this paper,I-shaped aluminum alloy parabola arch is taken as the research object.Theoretical derivation,numerical simulation and experimental analysis are used to explore the out of plane instability mechanism of parabola arch bridge.The specific research contents are as follows:(1)Based on the Cartesian theorem and the force method equation,the energy method is used to establish the parabolic fixed arch model under the concentrated force of the arch crown in the rectangular coordinate system,and the calculation formulas of the bending moment and axial force before buckling of the parabolic arch considering the shear deformation are proposed.By using the Rayleigh Ritz method,the out of plane displacement function and out of plane rotation function in the form of power series are proposed to construct the out of plane instability energy equation of parabolic fixed arch under the concentrated force of arch crown,and then the analytical solution of the critical load of out of plane instability of parabolic fixed arch under the concentrated force of arch crown is obtained.(2)By establishing the finite element model and comparing the numerical calculation results with the theoretical calculation results,the correctness of the calculation formula of the pre buckling bending moment and the axial force of the parabolic fixed arch under the concentrated load of the arch crown is verified,and the influence of the shear deformation on the pre buckling bending moment and the axial force of the parabolic arch is theoretically analyzed.The correctness of the theoretical derivation formula for the critical force of parabolic arch instability is verified,and the effect of shear deformation on the critical load of parabolic arch instability is theoretically analyzed.(3)Based on the results of the finite element model test,the fixed bearing with I-section,adjustable ratio of rise to span and adjustable span is designed.The loading system and displacement measurement system are designed,and then the parabola fixed connection under the action of the concentrated force of the arch crown is designed Out of plane instability test of arch.(4)Twelve different types of parabolic arches are tested.The load displacement curve,load strain curve,out of plane instability mode,torsional angle and out of plane instability critical load of parabola consolidation arch under the action of arch crown concentrated force are measured.Compared the measured data with the theoretical value and the simulation value of the finite element,the correctness of the test is verified.(5)Through the establishment of 132 sets of finite element models,the I-shaped section height,slenderness ratio,section type,different load positions,different load forms and other parameters were analyzed for the critical out-of-plane instability of the fixed parabolic arch under concentrated force Influence,thus systematically revealing the general mechanism of out-of-plane instability of the fixed parabolic arch plane.