Experimental Study On Seismic Behavior Of Reinforced Concrete Frame With Concentric Buckling-restrained Braces

As an innovative component to dissipate energy and reduce seismic response,buckling restrained braces(BRBs)perfectly solve the problem of buckling when compressed.BRBs can provide additional strength and stiffness for structure,effectively dissipate the earthquake input energy.It also has lots of advantages including rapid construction,easy replacement and so on.Owing to these advantages mentioned above,BRBs are gradually applied to practical engineering structures.In order to improve the seismic performance of reinforced concrete frames,and reduce reinforced concrete frames damage caused by earthquake,BRBs are utilized and installed into the reinforced concrete frames structures,forming a new kind structure system named as reinforced concrete frames with BRBs.Therefore,researches on the seismic design methods of reinforced concrete frames with BRBs,and promotion of application of BRBs in the reinforced concrete frames has both theoretical and practical significance.In this paper,two reinforced concrete frames,one without BRBs and the other with concentric BRBs as well as prestressd steel strip,were navigated through pseudo-static tests.During these tests,seismic performance of two frames including the failure modes,yielding mechanism,hysteretic curve,bearing capacity,lateral stiffness,ductility,energy dissipation capacity as well as the equivalent viscous damping ratios were analyzed and studied in detail.From the results,it could be concluded that the reinforced concrete frame with concentric BRBs and prestressed steel strip was well behaved and verified with higher seismic performance,in comparison to the reinforced concrete frame without BRBs.Additionally,the seismic performance of the reinforced concrete frames with threetype of layout of BRBs(one is single-diagonal BRBs,one is concentric BRBs,and another is eccentric BRBs)were tested respectively.Results indicated that the reinforced concrete frames with three type of layout of BRBs were improved in terms of seismic performance on the whole.However,slight differences also existed.The reinforced concrete frames with single-diagonal BRBs had clear force transferring route,but additional stress on columns was generated.The reinforced concrete frames with concentric BRBs lateral stiffness has been greatly improved,but resulted in unbalanced force at the intersection of the beam and BRBs.The reinforced concrete frames with eccentric BRBs had the most prominent bearing capacity and energy dissipation capacity.Based on the design of previous studies on how to design reinforced concrete frames with BRBs,and referring to the Code for Seismic Design of Buildings,a brief design method was proposed,and the calculation method of lateral stiffness of BRBs and the relationship of the BRBs core plate area,the BRBs equivalent area and the BRBs equivalent area in the model were summerized.