Experimental Research On Seismic Behavior Of Beam-column Joints With Ultra High Toughness Cementitious Composites

Ultra high toughness cementitious composite (abbreviated as UHTCC) is a new high performance fiber reinforced concrete, although it has only twenty years of the development history, but until now many experts and scholars have done a lot of experimental study on this material. With the development of its analysis theory and experimental study, this material has been successfully applied in many practical projects. The material has excellent basic mechanical properties, for its ductile failure under shear loading and its good improve structure capability of energy consumption and efficiently absorption of seismic energy, the material is applied on beam to column joints. In this paper, the five UHTCC new beam-column joints and two high strength concrete beam-column joints were carried out under low cyclic loading, the following work were completed:1. Introduce the failure process of specimens, describe the crack propagation on the core area of joints of four stage include incipient crack, the penetrating crack, limit state and failure stage, and analyze the reasons, draw conclusions that ultrahigh toughness cementitious composites has excellent crack self control ability and the crack can steadily develop after the first one.2. Give the main test results, including yield load and yield displacement, ultimate load and ultimate displacement, failure load and displacement. The ultimate bearing capacity is calculated with the application of theoretical formula of the shearing capacity of reinforced concrete and bending theory formula of this new material. A comparative analysis is done between the theoretical calculation and the experimental results, the error is little, experimental values and theoretical values are in good agreement.3. Give the cracking load of specimens, compared with the calculated value with the application of the theoretical formula. Propose a new influence coefficient η according to the experimental results. Using this influence coefficient, the calculated values have a good agreement with experimental results.4. In this paper, give the loading-displacement (P-A) hysteretic curves, because the compressive strength of UHTCC is much smaller than high strength concrete, only half, the loading-displacement (P-A) hysteretic curves are changed into nominal shear stress-rotation hysteretic curves to study the superior performance of the UHTCC material. On this basis, the displacement ductility, loop stiffness and energy are analyzed to study the seismic performance of UHTCC material on the beam-column joints.