Unified Evaluation of Failure Mechanism of Beam-Column Joint in Reinforced Concrete and Pre-stressed Concrete Frames

通过反复荷载作用下的静力试验，研究了平面和三维梁柱节点板的抗剪机理和破坏机理; 12个平面十字形试件和2个预应力钢筋混凝土三维试件（称为PRC）和预制预应力混凝土通过对PCaPC框架节点板的试验研究，得出如下结论：1）PCaPC框架中由四根横梁覆盖的节点板的剪切破坏与R/C梁柱节点相似;节点板内无粘结预应力筋的柱节点也发生了剪切破坏。3）十字形PCaPC梁柱节点板的抗剪强度可以采用与R/C梁柱节点相同的方法计算，即，4）4个或3个横向预应力筋的节点抗剪强度分别提高到25%和13 ...更多信息 5）双向荷载作用下各方向最大层间剪力的承载力点位于矩形双向剪力承载力相互作用面的外侧。这意味着PCaPC梁柱节点的地震安全性可以通过在各个方向上独立地设计节点来维持。6）对于PRC平面梁柱节点试件，观察到三种破坏类型。层间位移角在峰值抗剪承载力时的变化范围为1.5%~ 2.9%. 4个预应力混凝土筋加固的试件在层间位移角为2%时发生断裂，层间抗剪承载力显著下降。7）由于梁纵向钢筋或预应力混凝土筋的粘结破坏，而非受拉屈服，梁临界截面处的残余弯曲裂缝宽度突然增大。少

Shear resisting mechanism and failure mechanism of plane and three-dimensional beam-column joint panels were studied through a series of static tests under reversed cyclic loading; twelve specimens with plane cruciform shape and two three-dimensional specimens made of pre-stressed reinforced concrete (called as PRC) and precast pre-stressed concrete (called as PCaPC).Conclusions drawn by the study are mentioned as follows.1) Joint panel covered by four transverse beams in PCaPC frames failed in shear similarly to R/C beam-column joints.2) The beam-column joint with unbonded tendons within a joint panel also failed in shear.3) Shear strength of cruciform PCaPC beam-column joint panel can be computed by the same manner as R/C beam-column joints, i.e., as a function of concrete compressive strength regardless of the bond condition along beam post-tensioning tendons and the arrangement of the tendons.4) Joint shear strength was enhanced to 25 percent or 13 percent by four or three transver … More se beams framing into the joint panel respectively comparing with that of a plane beam-column joint specimen.5) The capacity point of a set of maximum story shear forces in each direction under bi-lateral loading was located at the outside of rectangular bi-directional interaction surface of joint shear capacity. This means that safety to earthquake excitations can be sustained for a PCaPC beam-column joint by designing joints to shear forces in respective directions independently.6) For PRC plane beam-column joint specimens, three failure types were observed. A story drift angle at the peak shear capacity varied from 1.5 % to 2.9 %. For four specimens which were reinforced by deformed PC tendons and failed by beam flexural yielding, PC tendons ruptured after a story drift angle of 2 % and lateral story shear capacity descended remarkably.7) Residual flexural crack width at beam critical sections increased suddenly due to no tensile yielding but bond deterioration of beam longitudinal reinforcement or PC tendons. Less