Seismic Performance Of The Retrofitted Damaged-RC-Frame With Cladding Panel

The cladding panel system is widely used in prefabricated buildings due to its high construction efficiency and low carbon environmental advantages.Moreover,the RC(reinforced concrete)frame structure with cladding panels has excellent seismic performance,with relatively less damage under seismic action,and has good restorability.However,current research on the RC frame structure with cladding panels mostly focused on the optimal design of panels and connections.The damage mechanism and repairable performance of the RC frame structure with cladding panels needs further study.To address this issue,this paper proposed a damage assessment method for the RC frame structure with cladding panels,and used this method to evaluate and repair two damaged-RC-frame with cladding panel specimens.The seismic performance of the repaired specimens was studied through quasistatic tests.A numerical model was established using the finite element software ABAQUS,and parameter analysis was conducted based on this model.The primary research themes and the corresponding achievements are presented as follows:(1)An analysis was conducted on the working mode of the sliding cladding system,the damage levels of the RC frame structure with cladding panels were classified,and the damage characteristics of each component of the cladding panel were defined under different damage levels.Two damaged-RC-frame with cladding panel specimens that were damaged in the initial quasi-static test were taken as the research object to evaluate the damage level of their cladding system and RC frame,and a targeted repair plan was developed.(2)The damaged-RC-frame with cladding panel specimens were subjected to quasi-static tests to study the damage patterns and seismic performance indicators such as hysteresis behavior,bearing capacity,stiffness degradation of the repaired specimens.The motion law and internal force distribution of different cladding panels were analyzed.The test verified the feasibility of repairing the damaged-RC-frame with cladding panel.The seismic performance of the two specimens was improved after repair and reinforcement.The horizontal bearing capacity was increased by 13.1% and 18.0% respectively,and the ultimate drift angle reached3.3%,meeting the requirement of 2.0% inter-story drift angle limit under rare earthquake.(3)Based on the experimental research,a solid model of the damaged-RC-frame with cladding panel was created using ABAQUS software,which simulated the working mode of the sliding connection node and the repair and reinforcement of the damaged specimens.The sliding node showed good adaptability under multiple seismic events,effectively reducing the damage to the main structure.In rare seismic events,the connection reached its limit,and the cladding panel participated in resisting seismic forces,leading to an increase in the peak bearing capacity of the RC frame structure with cladding panels.The deformation mode,damage characteristics,and load-displacement curves of the specimens obtained from the finite element analysis were consistent with the experimental results,confirming the accuracy of the modeling method.(4)Based on the established numerical model,the influence of different node connection methods,opening lengths,and structural damage levels on the seismic performance of the RC frame structure with cladding panels was studied.When using the flexible connection of sliding limited nodes,the bearing capacity of the RC frame structure with cladding panels was increased by 102.4% compared to the pure frame,and the increase was much higher than that of pure sliding connection nodes,while rigid connection would aggravate the damage of the main structure,so sliding limited nodes are the optimal connection form.The length of the node opening determines the limiting time of the cladding panel,and shortening the sliding distance of the bolt can improve the bearing capacity of the structure.After repairing damaged specimens of different damage levels,the CFRP cloth,cladding panel,and main structure showed good coordinated performance,and the bearing capacity of each specimen reached101.5%-88.4% of the original specimen.