基于破坏线模型的离心钢管混凝土扭转极限承载力

Torsional ultimate bearing capacity of centrifugal concrete filled steel tube based on model of failure line

在薄壁离心钢管混凝土构件扭转性能试验数据和离心钢管混凝土本构关系的研究基础上,针对离心钢管混凝土构 件在扭转性能试验塑性状态时钢管内离心混凝土发生约45°的脆性受拉破坏特性,提出了扭矩作用下离心钢管混凝土的 破坏线模型,由能量原理推出了管内混凝土的扭转刚度表达式,然后利用扭转刚度相等和边界条件将受压混凝土简化为 管内的等效螺旋加劲肋,提出了组合构件在纯扭转状态下极限承载力的简化计算公式。实例计算表明,本文提出的破坏线 模型其结果与他人研究成果和试验结果吻合较好。

The centrifugal concrete filled steel tube (CCFT) is a new type of structural material composed of steel and concrete, and is being applied to practical engineering construction. The torsional ultimate bearing capacity of CCFT has an important and complex mechanical characteristic and it is a matter of interest to engineers concerned in this field. On the basis of analyzing the torsional test results of CCFT, the constitutive relationship of CCFT and the phenomenon of brittle crack failure line with a degree of 45 in plastic stage of centrifugal concrete filled steel tube are studied in detail. A model of failure line for torsional ultimate bearing capacity of CCFT is presented in this paper. The formula for computing torsional stiffness of centrifugal concrete with this model is obtained by the principle of strain energy. The compressive centrifugal concrete within steel tube is simplified as the equivalent spiral rib stiffener by means of equal stiffness and boundary conditions, and the related simplified formula of torsional bearing capacity of CCFT under the state of pure torsion is presented. The analytical model proposed in this paper is compared with the experimental data reported and those in research papers. Their results are in good agreement with the experimental ones.