Research On The Seismic Performance Of The Connection Joints Of Commonly Used Assembled Monolithic Frame Structures During Service Life

Reduction seismic behavior of assembled concrete joints is likely to happen because of the deterioration of structural materials and weaker connection constraints of the joints.Typical joints for monolithic precast concrete frame structures were chosen as the research subject in this paper and numerical simulations based on finite element software ABAQUS as well as dynamic cyclic loading test were carried out to study the hysteretic performance of the joints.With reference to the concept of the Park-Ang damage model,the damage model for the seismic performance reduction of the joints during the service period was established combined with the degradation characteristics of important parameters such as deformation and energy dissipation.Using SAP2000 software,incremental dynamic analysis was performed on a monolithic precast concrete frame structure.And seismic fragility analysis was performed on the monolithic precast concrete structure.Primary conclusions achieved in this paper were listed as follows:(1)Based on the existing test data,mechanical models for the bonding performance of the interface between precast and cast-in-place concrete were established,which were simulated by setting non-linear springs in the finite element model of typical joint for monolithic precast concrete frame structures established by ABAQUS.The comparison between the simulation results of the hysteretic performance for the joint and the results of the dynamic cyclic loading test showed that the hysteresis curves obtained by the two methods could basically overlap,and the skeleton curve trend was consistent,meaning a good agreement.(2)Constitutive models of corroded reinforcement,carbonized concrete,and existing uncarbonized concrete were used in the time-dependent finite element model of typical joint for monolithic precast concrete frame structure to study the reduction law for its seismic performance during service period.The results showed that the bearing capacity,deformation ability,stiffness and energy dissipation ability of the joints hardly changed in the first 10 years,and they basically showed a linear downward trend after 10 years.The damage value was calculated using the damage model for the seismic performance reduction of the typical joint with ages.And the increase rate was slow in the first 10 years and became faster obviously after10 years,and it showed a linear growth trend.(3)Using SAP2000 software to conduct incremental dynamic analysis of the monolithic precast concrete frame structure,the results showed that,in the case of reaching the same damage level,the longer the service time,the smaller the ground motion strength that the structure need to input,indicating the seismic performance of the structure gradually weakened with the increase of service time.(4)The fragility analysis results of the monolithic precast concrete frame structure showed that: with the continuous reduction of the seismic performance of the joint for monolithic precast concrete frame structures,the possibility that the whole structure would reach each damage level under the same ground vibration intensity level was increasing.