异形截面多腔钢管混凝土柱约束效应作用机理及性能优化研究

Aiming at the common key scientific issue encountered in special-shaped CFT columns with multiple cavities in mega frame structures of super high-rise buildings, namely "the evaluation of the mechanical properties of special-shaped CFT columns with multiple cavities". Taking the confinement effect of steel tube on core concrete as the key connecting point, and the equivalent confinement coefficient and effective confinement discounting coefficient as the main connecting parameters, three types of CFT columns with different cross-sectional shape combinations, different cross-sectional structure combinations and different cross-sectional material combinations will be systematically studied. Experimental research, theoretical analysis and numerical calculation will be applied. The effect of various factors on the confinement effect will be analyzed. The correlation model between complex special-shaped CFT columns and common CFT columns will be established. By this way, the existing research results of common CFT columns can be applied to complex special-shaped CFT columns. The constitutive relation model of the concrete confined by special-shaped steel tube, which is based on Mander’s confined concrete model, will be proposed, as well as the mechanical analysis model. Moreover, they will be verified by the formerly tested data of special-shaped CFT columns with multiple cavities. The confinement mechanism will be reveal. Combining the engineering requirements, optimal design method for the mechanical properties will be given. As a result, the key design theory and technology will form.

针对超高层建筑巨形框架结构中异形截面多腔钢管混凝土柱遇到的共性关键科学问题，即“异形截面多腔钢管混凝土柱受力性能评估问题”。以钢管对核心混凝土的约束效应为关键联系点，以等效套箍系数和有效约束折减系数为主要联系参数，较系统的研究不同截面形状组合、不同截面构造组合、不同截面材料组合的三类异形截面钢管混凝土短柱轴压性能。采用试验研究、理论分析、数值计算相结合的方法，分析各因素对组合约束效应的影响，建立复杂异形截面多腔钢管混凝土柱与常规截面钢管混凝土柱关联性模型；将常规截面钢管混凝土柱已有研究成果应用于异形截面多腔钢管混凝土柱，提出基于mander约束混凝土模型的异形截面多腔钢管约束混凝土本构关系模型与力学分析模型，并采用已进行的异形截面多腔钢管混凝土柱试验数据进行验证，揭示约束机理；结合工程需求，给出受力性能优化设计方法，形成关键设计理论与技术。

针对超高层建筑巨型框架结构中,异形截面多腔钢管混凝土巨型柱截面尺寸巨大且截面构造复杂的特点，以及国内外相关标准中未包含相关设计方法的问题，对不同截面形状、分腔构造、加劲肋构造、含钢率、配筋率、混凝土强度等级等参数的钢管混凝土柱轴压性能进行试验研究，基于试验建立了异形截面单腔钢管混凝土柱“统一理论”计算模型、多腔钢管混凝土柱“分离法”计算模型、两类柱关联性规则，给出了异形截面多腔钢管约束混凝土的单轴本构关系与异形截面多腔钢管混凝土柱轴压承载力计算方法。研究表明：正多边形钢管混凝土有效与非有效约束区边界二次曲线初始切线角度与正多边形内角角度呈线性关系，并随着边数的增多而增大；在常规材料强度及含钢率情况下，标准GB50936中正方形、正八边形、正十六边形钢管混凝土轴压承载力，通过考虑形状效率系数折减约束效应后，可采用圆形截面公式及参数计算；截面规则性对钢管混凝土柱轴压承载力有一定影响，相同截面面积和含钢率条件下，正多边形约束效果最好，轴压承载力最高；异形截面多腔钢管混凝土柱拆分为若干单腔体钢管混凝土柱后，能够采用叠加法计算其承载力；提出的基于“分离模型”的多腔钢管约束混凝土本构关系，能够较准确的预测变形性能。本成果发展了异形截面多腔钢管混凝土柱设计理论与计算方法，预期可为类似工程的设计及标准编制提供参考，具有重要的应用价值。