Experimental Study On Shear Capacity Of Plastic Hinge In Seismic Design Of Bridge

At present,the code for seismic design of bridges in our country has adopted the ductility seismic design theory.According to this theory,the reinforced concrete bridge piers are used as the ductile members.Under the action of a large earthquake,the bridge piers can bend to yield and appear plastic hinge.Dissipation of seismic energy by elastic plastic deformation of plastic hinge.In order to ensure that the bridge piers in the large earthquake in the form of ductility response,we must ensure that the plastic hinge zone does not occur brittle shear failure.In this paper,the main research contents and conclusions of the shear capacity of reinforced concrete bridge pier plastic hinge zone are as follows:(1)The shear capacity designformula of seven typical reinforced concrete bridge piers at domestic and foreign was analyzed in detail.The shear strength of pierV_nare mainly composed of concrete shear contributionV_c and stirrups shear contribution V_s.(2)Thequasi-static loading testof reinforced concrete bridge piers wasdesigned.On the basis of the investigation of PEER,the size and the parameters of the test of the bridge piers were determined;detailed test plan is developed,andby the formula of ?/?=(?1/?2)·? innovation quasi-static test method by changing the position of loading(change the shear span ratio?),in order to achieve normal stress and shear stress redistribution in the process of piers flexural-shear failure.(3)The experimental phenomena and results were described and summarized.V_s formula of shear angle ?(the angle between the inclined cracks and the pier axis)is not a fixed value,it will increase with the increase of displacement ductility coefficient.Plastic hinge zone of core concrete crushing spalling,can cause between reinforcement and concrete core sliping,so that part of the stirrup shearcapacity out of action.(4)Based on the theoretical calculation results and the experimental results,the V_n is analyzed.It is concluded that Caltrans(2006)and "Code for Seismic Design of Urban Bridges"(2012)V_n calculated values are in good agreement with the experimental values,and the deviation between the calculated and experimental values of V_n is within 15%;"Guidelines of Seismic Design ofHighway Bridges "(2008)V_n calculated values,?? small pier for computing the partial conservative,?? larger piers for the calculation result is relatively large,unsafe.(5)Based on the theoretical calculation results and experimental results,the V_c is analyzed.It is concluded that the Priestley(1994)formula V_c(including axial compressionshear capacity contribution)is in good agreement with the experimental results,and the error is less than 12%;"Guidelines of Seismic Design ofHighway Bridges "(2008)V_c calculated value is too conservative,and V_c calculated value is smaller than the test value of 87% or more.(6)Based on the theoretical calculation results and experimental results,the V_s is analyzed.It is concluded that ATC-32(1995),Caltrans(2006),NZS3101(2006),"Code for Seismic Design of Urban Bridges"(2012)V_scalculated values are in good agreement with the experimental values,and the error is less than 28%;" Guidelines of Seismic Design ofHighway Bridges "(2008)V_s calculation error is larger.