Studies Of A New Type Of Column-to-Beam Joints By Embedded Steel Plate In Precast Concrete Frame Structures

Precast concrete structures are getting more and more attentions in China with the development of building industrial for their economic,fast-paced and environmental advantages..precast concrete frame system is widely used for commercial buildings,due to its superior strength and durability,design flexibility,aesthetic versatility,minimal site impact,faster construction times and reduced lifecycle costs..According to previous earthquake records,it can be found that the main damages of precast concrete structure occurred in the connection part which resulted in the collapse of the whole building.only slightly damage was occurred in prefabricated beams and columns,.Therefore,the key issue of precast frame structures is to ensure their colume-to-beam joints have good seismic performance.the optimal type of beam-column joint has always been the hot issue of the researchers in this field.In this thesis,a new type of beam-column connection was proposed for precast concrete frame structure.the precast column and the precast beam was connected by the embedded steel plate with high strength bolts connections.Full-scale tests were conducted on one cast-in beam-column joint and one precast beam-column joint.And the performances such as the hysteresis curves,skeleton curve,ductility,stiffness and energy dissipation capacity of these two kinds of joints were studied and compared.The experimental results showed that the new type precast column-to-beam joint had the same seismic performances with the traditional cast-in-site one.Then the finite element numerical models were established by the finite element software MSC.MARC and were verified by experimental results.Finally,parametric studies were conducted on the effects of plate thickness,plate length,tensile reinforcement area and axial compression ratio on the behaviors of the new type joint.Numerical results showed that the thickness of the plate and the axial compression ratio have little effection the behavior of the new type joint.While the embedded length of the plate and the area of tensile reinforcements had effects on the behavior of the joint.The strength capacity of the joint was reduced with decrement the length of the plate.Therefore,the embedded length of the plate need to meet the minimum anchorage length,otherwise the strength capacity and energy dissipation ability would be reduced.The strength capacity of the joint could be increased with the incensement of the area of tensile reinforcements.The research results in this thesis can provide some useful references for the application of precast concrete frame structure in engineering.