Earthquake Simulation Test And Analysis On Recycled Concrete Frame-shear Wall Structures

The development of recycled concrete structures has become an importantrequirement for the reclamation of construction waste and the recycling utilization ofbuilding materials. Existing studies on recycled concrete structures mainly are statictests. In order to investigate the mechanical performance of recycled concretestructures under dynamic load and evaluate the seismic capacity，six frame-shear wallstructures with different recycled aggregates replacement rates，different forms ofreinforcement and with or without energy dissipation braces, were tested on a shakingtable. The main contributions are as follows:1. Shaking table tests of four1/5scaled frame-shear wall structures were carriedout. The variable parameters considered in the test are the replacement ratio ofrecycled aggregates and the form of reinforcement. The four structures included onenormal concrete model, one recycled coarse aggregate concrete model, and tworecycled coarse and recycled fine aggregate concrete models with or withoutconcealed steel bar brace inside the shear wall. The natural frequency, accelerationresponse, displacement response and failure characteristics of models in differentstages were observed. The impacts of recycled aggregate replacement rate andreinforcement arrangement on seismic performance of frame-shear wall structurewere compared and analyzed.2. Shaking table tests of two1/5scaled frame-shear wall structures with energydissipation braces were carried out, including one recycled coarse aggregate concretemodel and one recycled coarse and recycled fine aggregate concrete model. Thenatural frequency, acceleration response, displacement response and failurecharacteristics of the two models in different stages were observed and compared withmodels without energy dissipation braces. The impact of energy dissipation braces onseismic performance of recycled concrete frame-shear wall structure was analyzed.3. Finite element models of the six frame-shear wall structures were created anddynamic time-history earthquake response analysis was conducted. The simulatedresults coincided well with the tested results.The main conclusions and suggestions:1. Compared with the normal concrete structure, the initial stiffness of the recycled concrete frame-shear wall structure is weaker and the shaking table’s peakacceleration when initial cracks appear is lower. The displacement response of therecycled concrete frame-shear wall structure is greater and the failure mechanism ofthe recycled concrete frame-shear wall structure is essentially same as the normalconcrete structure. The damage degree of the recycled coarse aggregate concretestructure is close to that of the normal concrete structure. The damage degree of therecycled coarse and recycled fine aggregate concrete structure is relatively severe.The seismic capacity of the recycled coarse concrete structure is relatively lower butstill meeting the requirements of seismic design. It can be applied in practicalengineering.2. The concealed steel bar brace has no obvious effect on increasing the model’sinitial stiffness but can reduce the displacement response. The concealed steel barbrace in shear walls can restrict the development of the cracks and improve thestructure ductility. The use of concealed steel bar brace in shear walls cansignificantly improve the seismic capacity of the recycled concrete frame-shear wallstructures and is suitable to be used in recycled concrete structures.3. The initial stiffness of the recycled concrete frame-shear wall structure withenergy dissipation braces is significantly increased and the speed of stiffnessdegradation becomes slower after cracking. The shaking table’s peak acceleration ofthe structure with energy dissipation braces when initial cracks appear is greatlyimproved. The use of energy dissipation braces also can reduce the displacementresponse and the damage degree.The seismic performance of the recycled concreteframe-shear wall structure with energy dissipation braces is highly improved and itcan well satisfy the aseismic capacity according to the current code for seismic designof buildings.4. The numerical simulation analysis method for the normal concrete structurescan be used for the recycled concrete frame-shear wall structures.