Comparative Research About Methods Of Strengthening Joints Of Frame By Enlarging Column Section, Bonding Steel Plates And Bonding CFRP

This paper takes crisscross frame joints without stirrup in core area as research subject, studying on its reinforcement problems. It analyzes three types of axial compression ratio (0.2, 0.5 and 0.8) and different joints strengthening methods under each kind of axial compression ratio. The methods contain column enlarging section strengthening, one layer carbon fiber strengthening, two layers carbon fiber strengthening, bonding steel plate strengthening (thickness t=3mm, steel plate yield strength fy=215 MPa), bonding steel plate strengthening (thickness t=3mm, steel plate yield strength fy=300MPa), bonding steel plate strengthening (thickness t=5mm, steel plate yield strength fy=215MPa). This paper also researches impact degree of strengthening on samples' ultimate bearing capacity, limit displacement, stiffness, tensility and energy dissipation ability.Based on broadly documents reading at home and abroad and drawing the strengthening experimental model in the past, this paper, in consideration of two kinds of loading system, i.e. one-shot loading and low cyclic reversed loading, builds a joint finite element model and carries a nonlinear analysis on this model with the structural analysis software ANSYS. Then, it postprocessor the software carries out nonlinearity analysis on the model, then, it draws the one-shot loading displacement curve and hysteresis curve in ANSYS processor. Analysis on these curves will induce the samples' ultimate bearing capacity, limit displacement, stiffness, tensility and energy dissipation ability.The analysis indicates that strengthening improves earthquake resistant behavior of joints. The strengthening effect is obvious and the method is feasible and effective.