Numerical Model of Frost-damaged RC Frame Beam-column Under Flexural Failure

In order to deeply explore the seismic capacity of the frost-damagedreinforced concrete (RC) frame beam-column subjected to flexural failure and then carry out an accurate evaluation.Based on the comparative analysis and summary of the existing quasi-static test data of frost-damaged RC beam and column at home and abroad,the influence of the number of freeze-thaw cycles NFTCs,concrete strength f_cu and axial force ratio n on the seismic capacity of RC beam-column is systematically explored.The calculation method of skeleton curve of moment-rotation (M-θ) hysteretic model of unfrozen RC frame beam-column under flexural failure is constructed theoretically.Moreover,a formula for calculating the M-θ skeleton curve of frozen-thawed damage RC frame beam-column under flexural failure is proposed considering the influence of freeze thaw damage parameters F (F combines the effects of NFTCs and f_c) and axial force ratio n.On this basis,based on the principle of energy dissipation,the cyclic degradation index β_i is introduced to characterize the strength degradation and stiffness degradation of beam-column members,and the M-θ restoring force model suitable for frost-damaged RC beam-column subjected to flexural failure is established.The M-θ hysteretic model of frost-damaged RC beam-column is substituted into the ZeroLength Element of OpenSEES,and the numerical model of frozen-thawed damage RC beam-column subjected to flexural failure is established by using the lumped plastic hinge model.The comparison results between the experimental and simulated indicate that the numerical model can accurately calibrate the hysteretic behavior of frost-damaged RC frame beam and column under low cyclic reciprocating loading,and can be used to evaluate the seismic capacity of RC frame structures.