穿心构造的钢管混凝土柱-钢梁节点抗连续性倒塌性能分析与评估

火灾、爆炸、撞击等突发事件可能造成建筑物发生连续性倒塌，二十世纪以来，随着国际上恐怖活动逐年增多，各国专家学者开始重视建筑防倒塌规范的制定和结构抗连续性倒塌性能的研究。目前，钢管混凝土柱-钢梁外环板式节点已被广泛应用于工程实例中，但其因在钢管外壁焊接外加强环板占用大量建筑空间，影响建筑物使用功能，而钢管混凝土柱-钢梁穿心式节点即钢梁整体或部分穿过钢管及钢管内填充的混凝土，大大节省建筑使用空间。为研究穿心型钢管混凝土柱-钢梁节点在连续性倒塌工况下的机制，利用ABAQUS有限元软件建立5个穿心构造的钢管混凝土柱-钢梁节点及1个全焊接节点模型，考察节点在连续倒塌工况下的抗力机制、变形模式及内力变化，并评估其节点的抗连续倒塌能力。结果表明：穿心型钢管混凝土柱-钢梁节点的连续倒塌破坏模式可分为钢梁倒塌破坏模式和柱壁倒塌破坏模式两种类型，柱壁倒塌破坏虽有更好的延性及承载力，但钢管壁鼓曲具有不稳定性。节点的竖向承载力主要由抗弯机制及悬链线机制提供，其中抗弯机制提供前期抗力，悬链线机制决定后期极限承载力。新型穿心构造的钢管混凝土柱-钢梁节点具有良好的抗连续倒塌能力，其节点抗连续倒塌性能评估指标η高于其余钢梁倒塌破坏节点。

Resistance to Progressive Collapse Performance Analysis and Assessment of CFST-steel Beam Joints with Through-center Construct

Incidents such as fires, explosions, and impacts may cause progressive collapse of building. Since the 20th century, as terrorist activities in the world have been increasing year by year, experts and scholars around the world have begun to pay attention to the formulation of building collapse prevention codes and structural progressive collapse resistance. At present, Concrete filled steel tube column (CFST)-steel beam joints with outer ring plate have been widely used in engineering examples. However, outer ring plates occupy a large amount of building space due to welding on the outer wall of steel tubes, which affect the function of buildings, and CFST-steel beam joints with through-center construct, that is, the steel beams are wholly or partially passed through the core concretes and the steel tubes, which greatly save the use space of the buildings. In order to study the mechanism of CFST-steel beam joints with through-center construct under progressive collapse conditions, ABAQUS finite element software was used to establish five CFST-steel beam joints with through-center construct and one fully welded joint models. The resistance mechanism, deformation modes and internal forces of the joint were investigated,and the capability of progressive collapse was evaluated. The results showed that the failure mode of CFST-steel beam joints with through-center construct can be divided into two types, the collapse failure mode at the beam and the collapse failure mode at the column. The collapse failure mode at the column has better ductility and bearing capacity, but with instability. The vertical bearing capacity of the joints is mainly provided by the bending mechanism and the catenary mechanism. The bending resistance mechanism provides the early resistance and the catenary mechanism determines the ultimate bearing capacity at the later stage. The new CFST column-steel beam joint with through-center structure has good capability of progressive collapse resistance, and its index of progressive collapse resistance of joint is higher than that of the other joints with collapse failure mode at the beam.