Research On Seismic Behavior And Shear Capacity Of SRC Beam-column Joints

Steel reinforced concrete(SRC) structures have been the most preferred structural forms for the multi-storey and tall buildings at present. For the SRC framework, the joint is a force transmission hub in the structural system, the shear failure of joint is one of the important causes of structural instability and collapse, thus ensuring the safety and reliability of the node is particularly important. Currently, the SRC beam-column joints with ordinary cross-shaped steel have been studied at home and abroad, and when the SRC column with bigger or oblique cross-shaped steel proposed by the research group intersect with the SRC beam with ordinary I-shaped steel, the mechanical properties are not clear. Under this background, in this paper, through the combination of experimental research, numerical simulation and theoretical analysis, the seismic performance and shearing bearing capacity calculation of the new SRC joints are studied. The main content is as follows:Experimental research on seismic behavior of SRC beam-column joints. Through the low cyclic reversed loading tests of 4 SRC column-SRC beam joints with bigger or oblique cross-shaped steel and 1 SRC column-SRC beam joint with ordinary cross-shaped steel, Failure patterns, hysteretic behavior, the bearing capacity and ductility of joints are studied, and the impacts of steel form, loading angle and structural measures on seismic performance are analyzed. The results indicate: When shear failure occur on all of specimens, the internal concrete can bear more loads; Compared to the SRC joints with ordinary cross-shaped steel, the new SRC joints are of full hysteretic curve and high bearing capacity, ductility and energy dissipation capacity; When the column contain oblique arrangement of cross shaped steel, or beam and column are orthogonal, the load carrying capacity and deformation performance of joints are more superior, and two kinds of structural measures have little effect on the seismic performance of joints.Numerical simulation study on seismic behavior of SRC beam-column joints. Based on ABAQUS platform, the finite element models of the specimens are built, and the mechanical properties under the cyclic load are analyzed. The hysteretic curves, skeleton curves and stress distribution are obtained by calculating, these results are close to the experimental results. And then the impact of axial compression ratio, concrete strength, the loading angle, the steel web width and thickness on the mechanical behavior of the joints. The results indicate: the increasing of the axial compression ratio, reducing of the concrete strength, increasing of loading angle will reduce the bearing ability; and increasing the thickness of steel plate is more effective than increasing the width for increasing bearing ability.Study on shear capacity of SRC beam-column joints. By the way of force analysis and equivalent transformation, the maximum value of shearing force is obtained. The calculation model of shear capacity is established, and by using the method of linear fitting to determine the two key factors, the calculation formulas of shear capacity that applies to the SRC beam-column joints in this paper are obtained,the results of formula calculation and the results of test and numerical simulation are in good agreement, and the proposed formula is more reasonable.