Behaviour And Design Of Stiffened Steel Plate Walls In High-rise Buildings Under Combined Compression And Shear

Steel plate walls(SPWs)are known as effective lateral load resisting elements due to the high lateral stiffness,ultimate shear strength and outstanding energy dissipation capacity.Therefore,SPWs become increasingly popular in the design of high-rise buildings.Most design guidelines require that SPWs should be designed to resist lateral forces only and should avoid resisting gravity loads.However,due to the limitation of erection period and the requirement of stability in construction stage,the final fixing between SPWs and boundary frames is generally not allowed to be postponed until the erection of all storeys.Therefore,SPWs are inevitably subjected to part of gravity loads,which may reduce the shear capacity of SPWs and lead to earlier buckling in service limit stage.Thus,stiffeners are required to improve the stiffness and buckling strength of SPWs.However,previous research was mainly focused on the hysteretic behaviour of stiffened SPWs with flat-bar stiffeners and the effect of torsional stiffness of stiffeners was not included.Hence,a series of analytical and numerical analyses are conducted to study the elastic and elastic-plastic stability of stiffened SPWs and the bending stiffness demand on stiffeners.The main content of the present thesis is summarized as follows:(1)The elastic compressive buckling stress of simply supported plates with one unloaded edge been rotationally restrained is studied.Then,the elastic compressive buckling behaviour of vertically stiffened SPWs is investigated.The effects of subpanels' aspect ratio,width-to-thickness ratio,number and torsional stiffness of stiffeners are included.Based on the understanding that the increment of elastic compressive buckling stress of stiffened SPWs over that of unstiffened SPWs is provided by vertical stiffeners,equations to predict the elastic threshold stiffness of vertical stiffeners are proposed and compared with previous studies(2)The effect of loading methods on the compressive post-buckling behaviour of simply supported plates is investigated.Based on the elastic buckling behaviour,the elastic-plastic compressive post-buckling behaviour of vertically stiffened SPWs is further studied.The distribution and development of compressive stress of stiffened SPWs with increasing bending stiffness of stiffeners are investigated.The effect of torsional stiffness of closed form stiffeners is included.Based on the effective width concept and the related elastic-plastic buckling strength of stiffeners,equations to predict the ultimate average compressive stress of stiffened SPWs are proposed and validated with tested specimens in open literature.For stiffeners of higher material yielding stress than that of the plate,equations for ultimate average compressive stress of stiffened SPWs are proposed on the basis of leaning column concept.For stiffened SPWs of given dimensions,comparison between the elastic threshold stiffness and the stiffness requirement in elastic-plastic analysis is presented under the common basis of same average compressive stress,which reveals the importance of elastic-plastic analysis.(3)The elastic compressive buckling of simply supported wide plates with one loaded edge been rotationally restrained is studied through analytical and numerical analyses.The elastic compressive buckling of horizontally stiffened SPWs is studied.The effects of subpanel aspect ratio,number and torsional stiffness of stiffeners are included.Based on the theory of the stability of parallel compressive struts been supported by horizontal beams,equations to predict the elastic threshold stiffness of horizontal stiffeners are proposed.(4)The post-buckling strength of wide plates under uniaxial compression is studied through numerical analysis and the improved equation is proposed on the basis of Eurocode 3.The elastic-plastic compressive post-buckling behaviour of horizontally stiffened SPWs is studied.The effect of torsional stiffness of closed form stiffeners is included.Based on the theory of the stability of parallel compressive struts been supported by horizontal beams,equations to predict the elastic-plastic threshold stiffness of horizontal stiffeners are proposed.Comparison between the elastic buckling and elastic-plastic post-buckling analyses is also presented.(5)The elastic shear buckling stress of simply supported plates with one or two side edges been rotationally restrained is investigated through numerical analysis.The elastic shear buckling of vertically stiffened SPWs is studied and the effect of torsional stiffness of stiffeners is included.Based on the understanding that the increment of elastic shear buckling strength of stiffened SPWs over that of unstiffened SPWs is provided by vertical stiffeners,equations to predict the elastic threshold stiffness are proposed and compared with the results in previous studies.(6)The shear post-buckling stiffness of nonlinear elastic SPWs is investigated through numerical analysis.The difference in the ultimate shear capacity between SPWs and webs of plate girders is investigated.The storey drift of simply supported plates at elastic-plastic shear buckling strength is determined.Based on the storey drift,the elastic-plastic shear buckling of vertically stiffened SPWs is studied.The effect of torsional stiffness of stiffeners is included.Based on the increment of elastic-plastic shear buckling stress of stiffened of SPWs over that of unstiffened SPWs,equations to predict the elastic-plastic threshold stiffness are proposed.Comparison between the elastic and elastic-plastic threshold stiffness is presented.(7)Comparison between elastic compressive and shear buckling behaviour is presented.The difference in elastic threshold stiffness of vertically stiffened SPWs in compression and in shear is investigated.The elastic buckling of vertically stiffened SPWs under combined uniaxial compression and shear loads is studied.The bending stiffness demand on stiffeners with different cross sections is determined as stiffened SPWs reach the elastic buckling stress specified by the interaction equation.Based on the equations for elastic threshold stiffness of vertically stiffened SPWs in compression and in shear,interaction equations are proposed to predict the elastic threshold stiffness of stiffened SPWs under combined compression and shear.(8)For simply supported plates under different pre-compressive load,the storey drift at elastic-plastic shear buckling stress is determined according to the interaction equation for elastic-plastic buckling stress under combined uniaxial compression and shear.Based on the storey drift,the elastic-plastic buckling of stiffened SPWs under combined compression and shear is then studied.The bending stiffness demand on stiffeners is determined for stiffened SPWs under different load combinations.The effect of torsional stiffness of stiffeners is also investigated.Equations for elastic-plastic threshold stiffness under combined loads are proposed on the basis of the equations for elastic and elastic-plastic threshold stiffness of vertically stiffened SPWs in compression and in shear,respectively.(9)A new design of horizontally stiffened SPWs is proposed.The horizontally stiffeners are made of hollow sections which can effectively reduce the compression load taken by SPWs through bending deformation.The elastic shear and compressive buckling of the new stiffened SPWs are studied.The bending stiffness demand on horizontal stiffeners is determined.The shear capacity of the new stiffened SPWs is investigated under different pre-compressive loads.Comparison is made among the new stiffened SPWs,unstiffened SPWs and common horizontally stiffened SPWs.