Numerical analysis on seismic behavior of beam-column joint with different cement-based materials

Abstract

Under cyclic loading conditions, the ductility of frame beam-column joints, which can be evaluated by the displacement ductility coefficient ( μ), is strongly affected by the axial load ratio ( n). Due to the high toughness of engineering cementitious composites (ECCs), the normal concrete can be replaced giving better joint ductility. However, the limit values of n for reinforced ECC (R-ECC) joints have not been clarified. Therefore, T- and cross-shaped reinforced concrete (RC) and R-ECC joint finite element models were established and analyzed under n values. The results indicated that the seismic performance of the joints, including μ, equivalent damping coefficient ( ξ eq), and secant stiffness ( K i) were strongly dependent on n. μ and ξ eq became inversely proportional to n when n was over 0.5. The RC and R-ECC joint ductile failure could occur when n was in the range of 0.3–0.7 and 0.3–0.9, respectively. The joint brittle failure occurred in RC and R-ECC joints when n was over 0.7 and 0.9, separately. Under the same n and load history, the maximum value of μ of R-ECC joints increased by 33.7% and 27.9% for T- and cross-shaped joints separately compared to that of RC joints. It is suggested that the n values for RC and R-ECC joints should not exceed 0.7 and 0.9, respectively.