板柱节点承载力计算方法研究进展

Research progress in bearing capacity calculation methods of column connections

摘要:

为促进板柱节点承载力研究的进一步开展,在简要介绍了国内外板柱节点发生破坏引起板-柱结构坍塌的工程事故之后,指出了板柱节点承载力计算方法存在的问题。论述了板柱节点发生冲切或弯冲破坏的破坏面倾角的试验结果和预估公式,针对按预估公式所得破坏面倾角计算值与试验值存在较大偏差的情况,提出了将板柱节点承载力试验结果置于以冲切和弯冲破坏面的倾角为纵坐标、分别以纵筋配置特征值ρfy/fc和冲跨比λ=(M_i)/[(V_ih0i)]为两个横坐标的三维坐标系中拟合获得破坏面倾角的思想。针对中国GB 50010—2010《混凝土结构设计规范》板柱节点承载力计算仅给出了冲切承载力公式,分析了国内外已有板柱节点承载力计算公式以及各公式中板的截面高度的影响。分析结果表明:板柱节点承载力计算应按冲切破坏、弯冲破坏和直冲破坏区别对待,计算时应合理考虑冲切或弯冲破坏面的倾斜角度,板柱节点承载力计算应综合考虑冲跨比和纵筋配置特征值等关键参数的影响,应进一步完善板柱节点发生直冲破坏的判据及承载力计算方法。

Abstract:

For the further research on the bearing capacity of slab-column connections, the engineering accidents of slab-column structure collapse caused by the failure of slab-column connections at home and abroad were introduced, and the problems existing in the calculation methods of bearing capacity of slab-column connections were pointed out. The test results and prediction formulas of the failure surface inclination angle of punching or bending-punching failure of slab-column connections were analyzed. In view of the large deviation between the calculated results of the inclination angle of failure surface obtained according to the prediction formulas and the test values, a method was proposed to obtain the failure surface inclination angle by fitting the bearing capacity test results of slab-column connections in three-dimensional coordinate system, which takes the inclination angle of the punching and bending-punching failure surface as the ordinate and the longitudinal reinforcement configuration eigenvalue ρfy/fc as well as the punching span ratio λ=(M_i)/[(V_ih0i)] as the abscissa. Considering that the Chinese code GB 50010—2010 Code for Design of Concrete Structuresonly provided the punching bearing capacity formula, the existing calculation formulas of the bearing capacity of slab-column connections at home and abroad were reviewed, and the influences of the section height of the slab in each formula were analyzed. The analysis results show that the calculation of bearing capacity of slab-column connections should be treated differently according to punching failure, bending-punching failure, and direct punching failure, and the inclination angle of punching or bending-punching failure surface shall be reasonably considered in the calculation. The influence of key parameters such as punching span ratio and longitudinal reinforcement configuration eigenvalue should be comprehensively considered in the calculation of bearing capacity of slab-column connections, and the criterion and bearing capacity calculation method of direct punching failure of slab-column connections should be further improved.