An investigation on shear strength of reinforced concrete columns strengthenedby concrete jacketing

摘要

The existing reinforced concrete buildings may need to be strengthened to reduce damages during upcoming earthquakes.The study reported in this paper is on strengthening of columns which are deficient in resisting shear during anearthquake,adopting concrete jacketing technique.Based on the previous studies,a need to develop a method topredict shear strength of jacketed columns,and to study the parameters affecting the strength was identified.To fulfilthese objectives,experimental and analytical studies were conducted on shear-critical concrete jacketed specimens.Thirty eight beam-column specimens were designed,prepared and tested,based on the selected parameters affectingshear strength.The parameters considered were,compressive strength ofjacket concrete,amounts of longitudinal andtransverse reinforcement ofjacket,thickness ofjacket and level of axial compression.All the specimens were designedto fail in shear.A method to compute the shear strength of a jacketed member,by extending the equations availablefor a monolithic section in selected standards is demonstrated.The method was validated using the test results.Next,the effects of the variations of the parameters on shear strengths of the jacketed members are illustrated.Finally,anoverview on the improvement in strength and behaviour due to jacketing is presented.