不同跨度比下腹板双角钢连接抗倒塌性能研究

以腹板双角钢连接的3个不同跨度比（1:0.6, 1:1.0, 1:1.4）两跨三柱型钢框架梁柱子结构为研究对象，通过单调静力加载试验和数值分析探究了其在连续倒塌条件下的破坏模式、力学形态、抗力机制和节点失效机理。结果表明，试件破坏均为失效柱与梁相连的两侧角钢因受拉发生断裂，且梁轴力、梁端节点转角以及角钢尺寸等是影响角钢肢断裂破坏的主要因素。3个试件具有相似的变形形态和破坏模式，其荷载峰值接近，但峰值荷载对应的失效柱水平位移随跨度比的增大而依次减小。对不等跨试件，变形较大时梁柱子结构因短梁梁端转角远大于长梁，使得内力重分布时线刚度较大的短梁将承担较多的水平荷载而先发生破坏。3个试件的抗力机制发展过程均可划分为梁机制与悬链线机制的混合阶段和悬链线机制阶段，且悬链线机制的充分发挥需要梁柱间具有可靠的拉结力。

Study on Anti-collapse Performance of Double Web Angles Connection Under Different Span Ratios

Three double-span assemblies with double web angles connection based on different span ratios (1:0.6, 1:1.0, 1:1.4) of steel frame were chosen as the research objects. The failure mode, the mechanical behavior, the resistance mechanism of specimens and the failure mechanism of joint were studied by monotonic static loading tests and numerical analysis under the condition of progressive collapse. The results show that the failure of all specimens is the fracture of double angles connecting the failure column and beam due to severe tension, in which the axial force in the beams, the beam-end rotation angle and the dimension of angles are main factors influencing the fracture of the angle leg. The deformation patterns and failure modes, as well as the peak loads, of three specimens are very close. Whereas the horizontal displacement of the failure column corresponding to the peak load reduces with the increase of span ratio successively. Differently, the short beam bears most horizontal load and is failure before long beam for the internal force redistribution of assemblies, which leads to the rotation at beam-end of the short beam being greater than the long one. The process of anti-collapse mechanism appears the flexure-catenary mixed phase and catenary phase, in which the reliably tension force between beam and column could make the catenary mechanism of the structure into full play.