Studies Of The Effects Of Adhesive Bolt Connections On The Steel Plate Strengthened Reinforced Concrete Coupling Beams

In recent years,seismic performances of buildings are paid more and more attentions by researchers.Many old reinforced concrete(RC)buildings in developed countries and cities need to be strengthened due to the introduction of new design loading requirements,rapid deterioration of reinforced concrete and in some cases poor original concrete quality.It is often more economical to retrofit affected structural components than to demolish the entire buildings.Reinforced concrete(RC)coupled shear walls and core walls are widely employed as a lateral load resisting system for high-rise buildings to resist earthquakes and wind loads.Coupling beams are essential structural elements in a seismic design due to their great ability to reduce considerably the bending moment at bottom of the coupled shear walls.Even local failure of coupling beams may lead to a serious global failure of the whole lateral resisting system.Therefore,in the earthquake resistant design of coupled shear wall system,the assessment of the failure mechanisms,post-elastic performance and ultimate strength of conventional reinforced coupling beams assumes particular importance.However,due to the limited door dimensions,the span to depth ratio of coupling beams are usually small and deep coupling beams with conventionally reinforced concrete tend to fail in a brittle manner and it may be difficult for them to possess the demanded ductility.Rare research has been done to improve the ductility and deformability of current deep coupling beams.Previous studies have proposed a new method(LRSP)to strengthen the existing reinforced concrete with steel plate and buckling controlled device.Through experimental studies,numerical investigations and theoretical analysis,this new retrofitting method(LRSP)has been validated to be a highly effective seismic strengthening method,which not only enhances bearing capacity and elastic performance of coupling beams,but also has good performance on energy-dissipation capacity and deformation properties.Based on above studies,this thesis focuses on the influence of bolt connections with or without adhesive injection on LRSP method.In this study,three test specimens of reinforced concrete coupling beams(DCB8-DCB10)with a ratio of 1:2 were conducted.Among which,the test specimen DCB8 was a original coupling beam without being reinforced by LRSP method;test specimen DCB9 was a coupling beam reinforced by LRSP method but without adhesive in the bolt connections;The specimen DCB10 adopted both the LRSP reinforcing method and adhesive bolt connections.After cyclic loading experiments,the performances of the three test specimens,such as shear capacity,energy-dissipation capacity,ductility and deformation were analyzed from test results.The experiment revels that the failure pattern of the control specimen DCB8 was very brittle.The shear capacity and ductility of the specimen DCB9 were not improved either.While the shear capacity and ductility were highly improved for DCB10 with adhesive bolt connections.This reasech reveals that the adhesive injected into the bolt connections hasgreat effect on the performance of retrofitted coupling beams.Based on the experimental and numerical studies,parametric studies were carried out to investigate the effects of stiffness of adhesive,different arrangement of bolts,stiffness and strength of bolt connection and with or without stiffeners on the internal force distribution of retrofitted coupling beams.