框架柱托换节点受力性能试验研究

Experimental study on mechanical behavior of frame column underpinning joints

通过移位工程框架柱包裹式托换节点缩尺模型的正交试验研究,分析托换梁剪跨比λ、纵筋配筋参数ρfy、配箍率、混凝土强度及梁柱结合面插筋配筋参数ρj fyj对托换节点破坏形态和受力性能的影响。试验结果显示,试件的破坏形态分为托换梁的受弯破坏和弯剪破坏两种形式,梁与柱结合面是薄弱位置;通过对试验数据回归分析,得到了在试验参数范围内各影响因素与托换节点破坏荷载的关系,所研究因素中剪跨比λ对托换节点承载力的影响最为显著,其次是纵筋配筋参数ρfy、配箍率和插筋配筋参数ρj fyj;依据试验结果提出了框架柱托换节点承载力计算公式,计算结果偏安全。

Through the orthogonal experiment of scaled models of the wrap-underpinning joints under frame columns in moving engineering,the influences of the shear-span ratio,longitudinal reinforcement parameter,stirrup ratio,concrete strength and dowel bar parameter in joint surface to the fracture morphology and bearing capacity were studied.The failure modes are classified to two forms： the flexure failure and the flexure-shear failure of the underpinning beams.The junction surface between beam and column is identified as a weak link.The crack development and final joint failure behavior were obtained.Based on the analysis and regression analysis of test data,relationship was obtained separately between each influencing factor and failing load in a certain range.The joint bearing capacity is influenced most significantly by the shear-span ratio.The longitudinal reinforcement parameter,stirrup ratio and joint bar ratio can also influence the joint strength.The formula to calculate the bearing capacity of underpinning joints was introduced.It is shown that calculated results are safe.