内填预置集料混凝土的圆钢管混凝土柱受压性能研究

Preplaced aggregate concrete with the advantages of vibration-free, low shrinkage, pouring compaction and less amount of cementitious material can fully play coarse aggregate interlock effect and framework role. Applying the preplaced aggregate concrete in concrete-filled steel tube structure is beneficial to improve the performance of concrete inside the steel tube and promote green and low-carbon development of concrete-filled steel tube structure. The circular steel tube column with preplaced aggregate concrete infill is set as main object in this project. The systematically research is conducted from three respects of mechanical properties and mechanical failure mechanism of preplaced aggregate concrete, interface bond-slip performance of circular steel tube-preplaced aggregate concrete and compression behavior of circular steel tube-preplaced aggregate concrete columns. Firstly, the influence factors of mechanical properties of preplaced aggregate concrete is analyzed, uniaxial compression constitutive model is established, failure mechanism under pressure is ascertained. Secondly, the evolution law of interface bond-slip performance of circular steel tube-preplaced aggregate concrete is revealed, shear force transfer mechanism of interface between circular steel tube and preplaced aggregate concrete is illustrated, the bond-slip constitutive model is built in combination with the finite element simulation results. Finally, the influence factors of axial and eccentric properties of circular steel tube-preplaced aggregate concrete columns are analyzed, the failure mechanism is verified, the numerical analysis model is established considering the properties of preplaced aggregate concrete and interface bond-slip performance, the calculation theory and design method of compression bearing capacity of circular steel tube-preplaced aggregate concrete columns are proposed. The scientific basis is provided for popularization and application of circular steel tube-preplaced aggregate concrete structures.

预置集料混凝土能够充分发挥粗集料嵌锁效应和骨架作用，具有免振捣、收缩小、浇筑密实和胶凝材料用量少等优点，应用于钢管混凝土结构有利于改善钢管内混凝土性能和促进该结构绿色低碳发展。本项目以圆钢管内填预置集料混凝土柱为主要对象，从预置集料混凝土力学性能及受压破坏机理、圆钢管-预置集料混凝土界面粘结滑移性能和圆钢管-预置集料混凝土柱受压性能三个方面展开系统研究。首先，分析预置集料混凝土力学性能影响因素，建立单轴受压本构模型，探明受压破坏机理；其次，揭示圆钢管-预置集料混凝土界面粘结滑移性能演化规律，阐明界面剪力传递机理，结合数值模拟结果建立粘结滑移本构模型；最后，探明圆钢管-预置集料混凝土柱轴压和偏压性能影响因素，揭示受压破坏机理，建立考虑预置集料混凝土性能和界面粘结滑移性能的数值分析模型，提出圆钢管-预置集料混凝土柱受压承载力计算理论与设计方法，为圆钢管-预置集料混凝土结构推广应用提供科学依据。

本项目以圆钢管内填预置集料混凝土柱为主要对象，从预置集料混凝土力学性能及受压破坏机理、圆钢管-预置集料混凝土界面粘结滑移性能和圆钢管-预置集料混凝土柱受压性能三个方面展开系统研究。主要研究内容和结论为：①研究了粗骨料性质、砂浆性能、注浆方法、注浆压力等因素对预置集料混凝土中砂浆填充性能的影响规律，建立了预置集料混凝土制备工艺控制指标体系。设计了12组预置集料混凝土配合比，开展了立方体抗压强度、轴心抗压强度、劈裂抗拉强度、抗折强度、弹性模量、单轴受压应力-应变曲线等试验，分析了力学性能影响因素，建立了受压本构模型，探明了受力破坏机理。②设计了12个圆钢管混凝土短柱试件，通过竖向推出试验研究了粗集料预置技术、预置集料混凝土强度等级、钢管径厚比、界面长度等因素对圆钢管-预置集料混凝土破坏形态、界面应力分布规律、粘结强度以及相对滑移等性能的影响规律，揭示圆钢管-预置集料混凝土界面剪力传递机理，建立了圆钢管-预置集料混凝土界面粘结滑移本构模型。③设计了10个圆钢管混凝土短柱试件和14个圆钢管混凝土中长柱试件。短柱方面：考虑集料预置技术、预置集料混凝土强度等级、钢材强度、钢管壁厚和钢管直径等因素进行了试件设计和轴压试验，建立了圆钢管-预置集料混凝土短柱的三维非线性有限元模型，模拟了试件在轴心受压下的力学行为，提出了适用于圆钢管-预置集料混凝土短柱的轴压承载力计算公式。中长柱方面：考虑集料预置技术、预置集料混凝土强度等级、径厚比、长径比和偏心率等因素进行了试件设计以及轴压和偏压试验，建立了圆钢管-预置集料混凝土中长柱三维非线性有限元模型，模拟了试件在轴心受压和偏心受压下的力学行为，提出了适用于圆钢管-预置集料混凝土中长柱轴压和偏压承载力计算公式。结合本项目研究工作的开展，培养1名博士研究生和5名硕士研究生，其中1名硕士研究生已毕业，发表9篇学术期刊论文（其中8篇SCI论文），获得1项实用新型专利。