Study on seismic behavior reduction of typical joints for monolithic precast concrete frame structures with ages

Abstract

PurposeMonolithic precast concrete frame structures have been promoted and developed in recent years. Owing to material deterioration and a weaker structural integrity, monolithic precast concrete frame structures may suffer from insufficient seismic capacity as service time increases. A typical joint of monolithic precast concrete frame structure is studied in this paper. The purpose of this paper is to perform numerical modeling of the typical joint subjected to low cyclic load at different ages and analyze the hysteretic behavior reduction with ages under common atmosphere environment.Design/methodology/approachExisting un-carbonated concrete, carbonated concrete and corroded rebar are all considered as deterioration factors for the typical joint, whose constitutive models are introduced into the finite element model to study. Moreover, time-dependent constitutive model of existing un-carbonated concrete and mechanical model of bond between precast and cast-in-place concrete are established on the basis of existing experimental data. Then, finite element method is used to investigate the seismic property reduction of the typical joint, where nonlinear springs are set to simulate bonding between precast and cast-in-place concrete.FindingsAnalyzing the results, the reduction of reaction force from skeleton curves of the joint is significant in the first 30 years of service time, and slows down after 30 years. Besides, the ductility, secant stiffness and equivalent viscous damping coefficient of the typical joint remain almost unchanged in the first decade, but decrease obviously after 10 years.Originality/valueThe originality of the paper consists in the following. The time-dependent constitutive model of existing un-carbonated concrete is established and used in finite element method. Besides, bonding between precast and cast-in-place concrete is considered using nonlinear springs. There is a reference value for the seismic performance assessment of existing monolithic precast concrete frame structures.