| SRC special-shaped column is combining with the advantages of steel and concrete, which reaches maximum advantage on SRC rectangular column and RC special-shaped columns, and it has been widely used. Joint is a hub to transfer force and an important forced location in the structure system, and it is very important to frame structure. The direction of the actual earthquake is arbitrary, and has a certain angle with the building axes. Force condition of SRC L-shaped column space corner joint is much more complicated because of asymmetry of L-shaped column. Therefore, it is necessary to research reasonable loading way, seismic performance, failure mechanism and the shear bearing capacity of space corner joint. On the basis of existing research, SRC L-shaped column space corner joint is systematically studied in this paper.12SRC L-shaped column space corner joint specimens are designed to carrying out the low cyclic loading test by self-designed loading device, and four vary parameters are considered, which are column section steel form, load angle, axial compression ratio and beam form. Failure patterns, load-displacement hysteretic curves and skeleton curves, load-strain hysteretic curve, the shear deformation at joint core area, mean curvature of beam cross-section and feature point parameters are obtained. The influences of vary parameters to seismic performance indicators are analyzed, which are peak load, displacement ductility, ultimate lateral angle, strength and stiffness degradation, energy dissipation capacity and accumulated damage. Test results indicate failure mechanism of SRC L-shaped column space corner joint presents shear-diagonal compression mainly, and bend torsion with bonding secondarily at joint core area for weak core specimen, and bending failure of beam end for strong column weak beam specimens. Hysteretic curve is full, displacement ductility, energy dissipation and the ability to resist collapse are better, strength and stiffness attenuation are slower, and comprehensive seismic performance is better. The peak load of solid web steel specimen is the highest, the ductility, collapse resistance and energy dissipation capacity of the specimens with T-shaped steel truss is the best, with the load angle decreases, peak load of the specimens reduces gradually, ductility increases slightly. Compared with45°load angle specimen, the peak load of0°load angle specimen is reduced by25%, and cumulative damage of0°load angle specimen at all levels displacement increases extremely30%. Stiffness degradation of0°load angle specimen is the fastest, that of30°load angle specimen is most slowly. Increasing axial compression ratio can improve energy dissipation capacity of specimens within a certain range, but its ductility and collapse resistance capacity becomes worse, and stifness degradation of the specimens more clearly. Compared with specimen with RC beam, the peak load of specimen with SRC beam increases38%, and cumulative damage has a larger degree of ease. Ductility and collapse resistance are all better. Stiffness degradation of specimens with RC beam are more obvious than that of specimens with steel beam.Specimens LJ-1?LJ-9are analyzed by finite element software Abaqus. Failure patterns are similar to the test, and the calculated hysteretic curves are more full and symmetrical than measured curves. The initial stiffness and the peak load is larger than test value, and the errors are within10%, which basically meets the general accuracy.74full scale specimens are designed, and the hysteretic characteristics is analyzed. Column section steel form, axial compression ratio, loading angle, concrete strength grade, limb high thickness ratio, steel ratio, ranging from limb, beam line stiffness and shear span ratio are considered as variable parameters, and the influence of variable parameters on the peak load of SRC space corner joint, energy dissipation and ductility are analyzed, which have good agreement with the test results. Base on the experimental results and finite element results, the main conclusions and recommendations from this paper are shown below:1) Compared with open spandrel steel specimens, the peak load of solid web steel specimens can increase by more than10%, comprehensive seismic performance is the best, so the solid web steel form should be the first choice in engineering practical design.2) The increase of the axial compression ratio decreases the displacement ductility of three kinds of steel forms specimens, especially the T-shape steel truss joint specimens with high axial compression ratio finds the most rapid. So for SRC L-shaped column space corner joint, the limit value of axial compression ratio is suggested to be0.5.3) The relationship of load angle and the peak load is reflected in axis symmetry of polar coordinate about45°. Within45°load angle, the peak load increases with the increase of load angle, the peak load of specimens under45°load angle is higher about30%than that of plane joint, and0°load angle is the most unfavorable loading direction. As the load angle increase, the energy dissipation and ductility of specimens reduce gradually. Compared with the plane node, the ductility of specimens under loading angle of45°reduces about10%, and bi-directional loading is likely caused a certain adverse effect on the ductility of the structure.4) The increase of concrete strength grade can reduce its ductility, so the optimal concrete strength grade is suggested to be C40.5) The increase of the limb high thickness ratio and column section steel ratio can increase the peak load and energy dissipation capacity of specimens, but leads to poor ductility, so the optimal limb thickness ratio is suggested to be3.0, and the optimal column section steel ratio is suggested to be4%?6%.6) The increase of two limb height ratio would increase the peak load and energy dissipation capacity of the specimen, the biggest up to16.2%. Even if ductility of specimens decrease, it is still more than3. For the actual needs of project, the commendable maximum height of the long limbs is960mm.7) The increase of beam linear stiffness can effectively increase the the peak load and ductility of the specimens. Compared with specimens which the beam column line stiffness ratio is0.10, the growth of the peak load of specimens which the beam column line stiffness ratio is0.45can reach more than2times and ductility increases68%, and the suggested linear stiffness is0.4-0.5.8) The increase of the column shear span ratio will greatly reduce the peak load of specimens; it also decreases the energy dissipation. When shear span ratio is between2.0-3.5, the ductility of the specimens is better, and the suggested shear span ratio is2.0?3.5, and the corresponding storey height is preferable2.80m-5.00m.Based on experimental research and finite element data fitting and regression. The shear capacity calculation formula of SRC L-shaped column space corner joint is proposed, and load angle, tensional reduce coefficient, axial compression ratio and the height ratio of beam to column are introduced in this formula. Verified by experimental result, the calculated results are proper. |
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