Research On The Shear Strength Of Normal And High-Strength Reinforced Concrete Bridge Columns

Bridge short columns designed in accordance with prevalent design standards may have inadequake seismic resistance.Special care is needed for shear strength of the columns under earthquake because it is a function of the flexural ductility and is one of key contents for capacity design philosophy.However,studies about the shear strength of RC bridge columns is scarce in China.In this paper,state-of-the-art of reversed cyclic tests,numerical analysis, repair techniques for damaged RC bridge columns are summarized.Thea,the shear strength of normal and high-strength concrete bridge columns is evaluated based on reversed cyclic loading tests.The detail works in this paper listed as follows:1.Reversed cyclic loading tests are conducted for normal and high-strength concrete bridge columns to evaluate the failure mechanism and shear strength of the columns. Meanwhile,seismic performance of RC bridge columns designed using displacement-based method and repair techniques are verified by cyclic tests.It can be concluded that high-strength concrete columns may have ductile behavior if the specimens designed with adequate lateral confinement,the proposed seismic design method based on displacement is feasible.It could be recgnized that the columns designed accordance to current seismic design codes in China may suffer nonductile shear or flexural-shear failure modes under earthquakes, which need special attention in future.2.Existing design equations for shear strength of the columns are compared with each other based on experimental results.Then,aspects relating to the shear strength of columns under seismic loading are studied based on the author's experimental results and PEER database.At last,a suggested equation for shear strength of the columns is proposed for chinese bridge seismic design code.3.Model approaches describing the hysteretic behavior of RC bridge columns subjected to cyclic loading are investigated.A set of model with different parameters is selected by using ANSYS software and evaluated through comparison with experimental results.The influences of the shear retention coefficients,the Bauschinger effect of reinforcing steel,the bond-slip relationship between the longitudinal reinforcement and the concrete,the concrete failure surface on the calculated results are discussed.Then,a modified analysis model is presented and the model accuracy has been verified by comparing the calculated hysteretic curves and skeleton curves with experimental results.