Research On Seismic Performance Of Retrofitting New Concrete Beam-column Joints

In an increasingly sophisticated social construction, there are increasing projects ofrenovation and reinforcement of existing buildings as a result of changing of people’s life, joband material needs, many of which involve adding new concrete beam-column joints orretrofitting the existing concrete beam-column joints. Beam-column joints is an important partof the framework structure, therefore, it has important theoretical significance and engineeringapplication value to syudy minutely the connection method of retrofitting beam-column jointsand its mechanical properties, especially the seismic performance of new beam-column joints.Firstly, the working characteristics, loading mechanism and anchorage system performanceanalysis of the old and new concrete structures is studied from the theoretical aspects, thefactors influencing the seismic performance of new retrofitting joints is acquired. Then,numerical simulation method is used, in which nine models of four series is established. Thereliability of adding nodes by anchoraging methods is verified through numerical simulationand engineering examples. The influence of anchorage location, anchorage length, diameterof anchorage and other factors on seismic performence of new concrete beam-column joints isdiscussed, the following conclusions can be drawn: when the additional anchorage length is15d, the beam-column joints bars have undergone varying degrees of slip. To improve theseismic performance of beam-column joints, the additional anchorage length increase to18d,which effectivey reduces the slip phenomenon. The ultimate bearing capacity of nodes isimproved, and the seismic performance of the retrofitting specimen is close to the the entirecast nodes.(2) Increasing the diameters of anchorage can improve the load capacity ofbeam-column joints, reduce slippage and improve the anti-shear capacity. But with theanchorage diameter increases, the ductility decreased. The larger the diameter of anchorage,the worse the stiffness of anchorage degradats.(3) The anti-shear capacity formula of retrofitting new concrete beam-column joints is preliminary obtained.The conclusion of this study can be a reference for further research on the mechanicalproperty of retrofitting new concrete beam-column joints and engineering design andconstruction.