A beam-column joint of precast and partial steel reinforced concrete( PPSRC) is proposed for precast reinforced concrete frames. The PPSRC consists of partial steel and reinforced concrete. The partial steel is locate...A beam-column joint of precast and partial steel reinforced concrete( PPSRC) is proposed for precast reinforced concrete frames. The PPSRC consists of partial steel and reinforced concrete. The partial steel is located in the core joint region and the connections between concrete members. This paper presents an experimental study of a series of PPSRC specimens. These specimens are tested under low cyclic loading.Experimental results demonstrate that the bearing capacity of the PPSRC specimens is 3 times that of the ordinary reinforced concrete( RC) beam-column joints. The strength and stiffness degradation rates are slower compared with that of the RC beam-column joints. In addition,the strength of the core joint region and the connections is higher than other parts of the PPSRC specimens. Beam failure occurs firstly for the PPSRC specimens,followed by column failure and connections failure. The failure of the core joint region occurs finally.Test results show that the seismic performance of the PPSRC is better than that of the ordinary RC beam-column joints.展开更多
A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic ...A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic loading were tested to study the static behavior of this new type of joint.The main variable parameters for the five joint specimens were the longitudinal reinforcement ratio and the joint type.The experimental results designated that the magnitude of extension of the longitudinal reinforcement is the most important factor that influenced the moment-rotation characteristic of the new type of joint.The concrete slabs could resist 3.8%-19.1% of the total shear load applied to the cross-sections near the beam-to-column connection.The edge stiffened elements,such as the flange of the lipped I-section thin-walled steel beam,were capable of having considerable inelastic deformation capacity although they had comparatively large width-to-thickness ratios.The shear failure of the concrete cantilever edge strip must be taken into account in practical design because it has significant influence on the anchorage of the longitudinal reinforcement in the new type of external joints.展开更多
To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SRC) beams, six interior frame joint specimens...To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SRC) beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirIup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete (SRC) frame joint and RC frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.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
In practical design,the joints with outer stiffening ring were used to connect concrete beams and laminated steel tube columns.The seismic behavior of joints with outer stiffening ring with various types was studied b...In practical design,the joints with outer stiffening ring were used to connect concrete beams and laminated steel tube columns.The seismic behavior of joints with outer stiffening ring with various types was studied based on experiments.The bearing capacity,rigidity,ductility,energy dissipation capacity,deformation property and strain distribution of the joints with outer stiffening ring with various types were comprehensively evaluated based on the test results of three specimens under quasistatic cyclic loading and finite element analysis.The test results showed that the failure mode,hysteretic behavior,bearing capacity and rigidity degradation of the joints with outer stiffening ring with various types were nearly identical.Furthermore,the strain distribution of the outer stiffening ring of the three joints was nearly the same.The detailing recommendation for the outer strengthening rings was proposed for the concrete beam-laminated steel tube column joints with outer stiffening ring,in order to ensure the good seismic capacity of the joints.展开更多
This paper presents an experimental study investigating factors influencing the effective width of steel reinforced concrete (SRC) column-steel beam joints of building in order to calculate its resisting moment.Five 1...This paper presents an experimental study investigating factors influencing the effective width of steel reinforced concrete (SRC) column-steel beam joints of building in order to calculate its resisting moment.Five 1/2 scaled interior SRC column-steel beam joint specimens were made with considering parameters such as beam flange width,beam depth and SRC column width.One directional increasing moment was applied to the joint by acting forces to each ends of beam and the structural behavior of joint was studied.And previous design method suggested by Deierlein was reviewed and a modified equation was proposed from the analysis of test result.Test result indicated that the equation to calculate the effective width in Deierlein’s design method didn’t consider effectively the influence caused by the variation of beam depth so that a modified equation was suggested and the validation of it was confirmed in this paper.展开更多
文摘A beam-column joint of precast and partial steel reinforced concrete( PPSRC) is proposed for precast reinforced concrete frames. The PPSRC consists of partial steel and reinforced concrete. The partial steel is located in the core joint region and the connections between concrete members. This paper presents an experimental study of a series of PPSRC specimens. These specimens are tested under low cyclic loading.Experimental results demonstrate that the bearing capacity of the PPSRC specimens is 3 times that of the ordinary reinforced concrete( RC) beam-column joints. The strength and stiffness degradation rates are slower compared with that of the RC beam-column joints. In addition,the strength of the core joint region and the connections is higher than other parts of the PPSRC specimens. Beam failure occurs firstly for the PPSRC specimens,followed by column failure and connections failure. The failure of the core joint region occurs finally.Test results show that the seismic performance of the PPSRC is better than that of the ordinary RC beam-column joints.
基金Sponsored by the National Natural Science Foundation of China (Grant No.50478027)
文摘A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic loading were tested to study the static behavior of this new type of joint.The main variable parameters for the five joint specimens were the longitudinal reinforcement ratio and the joint type.The experimental results designated that the magnitude of extension of the longitudinal reinforcement is the most important factor that influenced the moment-rotation characteristic of the new type of joint.The concrete slabs could resist 3.8%-19.1% of the total shear load applied to the cross-sections near the beam-to-column connection.The edge stiffened elements,such as the flange of the lipped I-section thin-walled steel beam,were capable of having considerable inelastic deformation capacity although they had comparatively large width-to-thickness ratios.The shear failure of the concrete cantilever edge strip must be taken into account in practical design because it has significant influence on the anchorage of the longitudinal reinforcement in the new type of external joints.
基金National Natural Science Foundation of China Under Grant No.50878037
文摘To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete (SRUHSC) columns and steel reinforced concrete (SRC) beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirIup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete (SRC) frame joint and RC frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.
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.
基金supported by Twelfth"Five-Year"Plan Major Projects supported by the National Science and Technology Pillar Program of China(Grant No.2011BAJ09B01)Tsinghua University Initiative Scientific Research Program(Grant No.2010Z03078)
文摘In practical design,the joints with outer stiffening ring were used to connect concrete beams and laminated steel tube columns.The seismic behavior of joints with outer stiffening ring with various types was studied based on experiments.The bearing capacity,rigidity,ductility,energy dissipation capacity,deformation property and strain distribution of the joints with outer stiffening ring with various types were comprehensively evaluated based on the test results of three specimens under quasistatic cyclic loading and finite element analysis.The test results showed that the failure mode,hysteretic behavior,bearing capacity and rigidity degradation of the joints with outer stiffening ring with various types were nearly identical.Furthermore,the strain distribution of the outer stiffening ring of the three joints was nearly the same.The detailing recommendation for the outer strengthening rings was proposed for the concrete beam-laminated steel tube column joints with outer stiffening ring,in order to ensure the good seismic capacity of the joints.
基金supported by a grant from the Academic Research Program of Chungju National University in 2011
文摘This paper presents an experimental study investigating factors influencing the effective width of steel reinforced concrete (SRC) column-steel beam joints of building in order to calculate its resisting moment.Five 1/2 scaled interior SRC column-steel beam joint specimens were made with considering parameters such as beam flange width,beam depth and SRC column width.One directional increasing moment was applied to the joint by acting forces to each ends of beam and the structural behavior of joint was studied.And previous design method suggested by Deierlein was reviewed and a modified equation was proposed from the analysis of test result.Test result indicated that the equation to calculate the effective width in Deierlein’s design method didn’t consider effectively the influence caused by the variation of beam depth so that a modified equation was suggested and the validation of it was confirmed in this paper.