工字形CFRP型材-方钢管-混凝土组合构件的性能

The CFRP has characateristic of light weight, high-strengh and good compressive property. When the I-shaped CFRP is put into the concrete filled square steel tube, steel tube and concrete could restain the transverse deformation of the I-shaped CFRP profiles, prevent them from buckling and brittle failure.So the compressive high-strengh of the I-shaped CFRP could be played fully.In additon, the I-shaped CFRP profiles can also delay the developping of the shearing diagonal crack to improve the ductility of the members.Compared with the ordinary CFST column, the members with inner I-shaped CFRP profiles can further reduce the sectional dimensions of components, decrease the size of foundation and load ,reduce seismic response of structure and improve the structure ductility. The theoretical analysis, numerical modeling and experiment are carried out to study mechanical properties of axial compression for short columns, middle long columns, long columns, beam columns, one-way eccentric columns, two-way eccentric columns,etc, and put forward the formulas on bearing capacity and deformation of the components on the basis of studying constitutive relationship of concrete filled square steel tubular column with inner I-shaped CFRP profiles and cooperative working mechanism of composite materials. And practical designing methods of various components of concrete filled square steel tubular column with inner I-shaped CFRP profiles are presented, in order to lay the theoretical groundwork for the application of this new structural system and make contributions to sustainable development of civil engineering.

CFRP型材轻质高强、抗压性能好，将工字形CFRP型材内置于方钢管混凝土中，钢管和混凝土能抑制其横向变形，防止其发生屈曲及脆性破坏，充分发挥其高强抗压性能；工字形CFRP型材，也能延缓混凝土剪切斜裂缝的开展，从而提高构件的延性。与普通钢管混凝土柱相比，工字形CFRP型材-方钢管-混凝土组合柱可进一步减小构件截面尺寸、降低结构自重、减少基础尺寸和负荷、降低结构的地震反应而且提高结构延性。本项目采用理论分析、数值模拟与试验研究相结合的方法，在研究工字形CFRP型材-方钢管-混凝土组合材料的承载力指标、本构关系及协同工作机理的基础上，研究工字形CFRP型材-方钢管-混凝土轴心受压短柱、中长柱、长柱，纯弯构件，单向、双向偏心受压柱等的性能，提出各类构件的承载力、变形等的计算方法；提出工字形CFRP型材-方钢管-混凝土各类构件的实用设计方法，为使这种新型结构体系能够应用于工程实践奠定坚实的理论基础。

为了满足快速发展的大跨度、超高层建筑的需求，内置工字形CFRP型材的钢管混凝土柱这种结构形式被开发出来，然而，国内及其他国家和地区的有关设计规范中的计算方法并不能准确计算该类构件的极限承载力。因此，对于此类组合构件深入开展静力性能研究具有重要的理论意义和实用价值。本项目以内置工字形CFRP型材的方钢管混凝土柱为研究对象，深入研究了其在轴压、偏压以及纯弯矩作用下工作机理的研究工作。进行了轴压短柱、中长柱以及长柱的试验研究，结合有限元分析，得到了轴压状态下的荷载应变曲线、荷载中截面侧向挠度曲线及荷载应力曲线，给出在轴压状态下组合构件的约束指标以及稳定系数，定义了轴压中长柱、长柱的界限长细比，得出组合构件轴压短柱、中长柱与长柱承载力计算方法；进行了纯弯构件的试验研究，结合有限元分析，得到了纯弯构件的弯矩-曲率关系曲线，研究了纯弯构件混凝土应力与应变分布、钢管应力与应变分布以及中性轴的变化规律等，分析了不同含钢率、钢管屈服强度、混凝土抗压强度对纯弯构件极限承载力、抗弯刚度、延性等的影响，得出了纯弯构件抗弯承载力计算方法；进行了压弯构件试验研究，结合有限元分析，对典型构件荷载-中截面侧向挠度曲线进行定义，比对了材料间相互作用力的大小，比较了不同截面处材料应力的分布情况以及不同截面处材料承担的荷载情况，通过参数分析研究了偏心率、长细比、混凝土强度、钢材屈服强度以及含钢率对组合构件性能的影响，得出压弯构件承载力计算方法。