This paper describes a series of experimental investigations on seventeen specimens of steel reinforced concrete special shaped(SRCSS) columns under low cyclic reversed loading using parallel crosshead equipment. Nine...This paper describes a series of experimental investigations on seventeen specimens of steel reinforced concrete special shaped(SRCSS) columns under low cyclic reversed loading using parallel crosshead equipment. Nine T-shaped SRC columns, four L-shaped SRC columns and four +-shaped SRC columns were tested to examine the effects of shape steel confi guration, loading angle, axial compressive ratio and shear-span ratio on the behavior(strength, stiffness, energy dissipation, ductility, etc.) of SRCSS column specimens. The failure modes and hysteretic performance of all the specimens were obtained in the tests. Test results demonstrate that the shear-span ratio is the main parameter affecting the failure modes of SRCSS columns. The specimens with small shear-span ratio are prone to shear failure, and the primary failure planes in SRCSS columns are parallel to the loading direction. As a result, there is a symmetry between positive and negative loading directions in the hysteretic curves of the SRCSS columns. The majority of displacement ductility coeffi cients for all the specimens are over 3.0, so that the SRCSS columns demonstrate a better deformation capacity. In addition, the equivalent viscous damping coeffi cients of all the specimens are greater than 0.2, indicating that the seismic behavior of SRCSS columns is adequate. Finally, the superposition theory was used to calculate the limits of axial compressive ratio for the specimens, and it is found that the test axial compressive ratio is close to or smaller than the calculated axial compressive ratio limit.展开更多
To overcome the problem that steel bars are put too close at a flame joint with special-shaped beam and column,mechanical performance of three groups of six RC flame joints with special-shaped(L,T and+)column and disp...To overcome the problem that steel bars are put too close at a flame joint with special-shaped beam and column,mechanical performance of three groups of six RC flame joints with special-shaped(L,T and+)column and dispersed-steel bars-beam on the top floor under cyclic loads were studied.Experimental comparison was conducted between special-shaped(L,T and+)column and normal beams.The cracking load,yielding load,ultimate bearing capacity,failure patterns,and hysteretic properties at joint core area were investigated.The seismic behaviors of the joints with different proportions of dispersed-steelbar beams were analyzed.The results of experimental analysis indicate that the mechanical and seismic behaviors of frame joints with T-shaped and+-shaped column are nearly not changed when suitable proportion steel bars are dispersed to flange plane.Stiffness degeneration of flame joint with L-shaped column is rather serious due to concrete damage stiffness.Theoretical result indicates that distributing area of the dispersed steel-bar beams in the flange plate should be strictly controlled to avoid anchor destroy.展开更多
基金National Science Foundation of China under Grant Nos.50908057 and 51268004Open Project of Guangxi Key Laboratory of Disaster Prevention and Structural Safety under Grant No.2012ZDX10Innovation Project of Guangxi Graduate Education under Grant No.YCBZ2012005
文摘This paper describes a series of experimental investigations on seventeen specimens of steel reinforced concrete special shaped(SRCSS) columns under low cyclic reversed loading using parallel crosshead equipment. Nine T-shaped SRC columns, four L-shaped SRC columns and four +-shaped SRC columns were tested to examine the effects of shape steel confi guration, loading angle, axial compressive ratio and shear-span ratio on the behavior(strength, stiffness, energy dissipation, ductility, etc.) of SRCSS column specimens. The failure modes and hysteretic performance of all the specimens were obtained in the tests. Test results demonstrate that the shear-span ratio is the main parameter affecting the failure modes of SRCSS columns. The specimens with small shear-span ratio are prone to shear failure, and the primary failure planes in SRCSS columns are parallel to the loading direction. As a result, there is a symmetry between positive and negative loading directions in the hysteretic curves of the SRCSS columns. The majority of displacement ductility coeffi cients for all the specimens are over 3.0, so that the SRCSS columns demonstrate a better deformation capacity. In addition, the equivalent viscous damping coeffi cients of all the specimens are greater than 0.2, indicating that the seismic behavior of SRCSS columns is adequate. Finally, the superposition theory was used to calculate the limits of axial compressive ratio for the specimens, and it is found that the test axial compressive ratio is close to or smaller than the calculated axial compressive ratio limit.
基金This work was partly financial supported by the National Natural Science Foundation of China(Grant No.50678016).
文摘To overcome the problem that steel bars are put too close at a flame joint with special-shaped beam and column,mechanical performance of three groups of six RC flame joints with special-shaped(L,T and+)column and dispersed-steel bars-beam on the top floor under cyclic loads were studied.Experimental comparison was conducted between special-shaped(L,T and+)column and normal beams.The cracking load,yielding load,ultimate bearing capacity,failure patterns,and hysteretic properties at joint core area were investigated.The seismic behaviors of the joints with different proportions of dispersed-steelbar beams were analyzed.The results of experimental analysis indicate that the mechanical and seismic behaviors of frame joints with T-shaped and+-shaped column are nearly not changed when suitable proportion steel bars are dispersed to flange plane.Stiffness degeneration of flame joint with L-shaped column is rather serious due to concrete damage stiffness.Theoretical result indicates that distributing area of the dispersed steel-bar beams in the flange plate should be strictly controlled to avoid anchor destroy.
