Study On The Influence Of Construction Defects On The Width Ratio Limit Of Concrete Thin-walled Hollow Pier

Hollow thin-walled bridge piers are common structural forms in mountainous highway bridges.They are usually constructed by means of sliding membranes,climbing molds or overturning molds.In actual construction,problems such as misaligned piers,explosive molds,or insufficient concrete strength often occur.As the altitude increases,its stability has become an important issue for structural safety.Therefore,it is of great engineering significance to carry out research on the factors that affect the overall stability and local stability of thin-walled hollow piers.In this paper,the thin-walled high-rise piers are simplified as the central compression rods,considering the overall stability under the influence of construction defects;the high-rise piers are simplified into plates for study,and the critical thickness and the limit width-thickness ratio under known plate widths are explored..The research content of this paper mainly includes three aspects:(1)Starting from the deflection curve differential equation of the compression member,assuming the initial bending equation,the critical load of the free rod member at the upper end of the consolidated upper end is deduced using the fiber yield criterion.(2)Using the isotropic and orthotropic properties of the slab to derive the critical load of the local instability,combined with the critical stress formula of the overall instability,the thin-walled hollow pier is regarded as a component consisting of thin plates,and the piers are preferentially destabilized.As a control condition,the critical thickness and the limit thickness-to-thickness ratio formula of the iso-section piers were deduced.(3)An ANSYS finite element model was used to build the shell element model.After the initial bending,the first type of stability analysis was performed on the local stability of thin-walled high piers.The formula was compared with the results of the finite element model to verify the correctness of the formula.Sex,the results show:1 The calculated results of the equation under the isotropic and orthotropic plate theory are in good agreement with the finite element analysis results,and the critical width-thickness ratio formula is feasible.2 When the height of the pier increases,the critical width of the thin plate will become smaller.This is mainly due to the fact that as the height increases,the influence of the initial defect increases,and the critical load decreases significantly.3 Under the same conditions,the results calculated by orthotropic plate theory are closer to the results of the finite element analysis.The accuracy of the formula is higher,and the result according to the isotropic plate theory is poor.This is mainly due to the fact that orthotropic plates are more in line with the actual project,taking into account the elastoplastic effect of the material.