格构式钢管混凝土构件的滞回性能及抗震设计方法研究

Concrete-filled steel tubular (CFST) latticed members have a large cross-sectional moment of inertia due to the main load-bearing limbs being away from the centroidal axis. Compared with single CFST members under the same conditions, CFST latticed members have a lighter weight, a better axial stability and a larger flexural stiffness. In practical engineering, CFST latticed member is adopted when the member has the large load eccentricity ratio and slenderness ratio, such as column of industrial plant, trestle column, high pier and arch rib of arch bridge, etc. Intensive studies for hysteretic performance of CFST latticed members are the important premise for reasonable assessment of earthquake damage evolution and further development of rational seismic design method of CFST latticed members. The purpose of this project is to theoretically and experimentally investigate the hysteretic behavior of CFST latticed members. The non-linear finite element theory and elasto-plastic constitutive relationship of materials will be used to establish the theoretical model for analysis of the hysteretic behavior of CFST latticed members subjected to cyclic loadings, and the tests of typical CFST latticed members and connections between limbs and lacings will be carried out to verify the analytical theory and model. Through the implementation of this project, the mechanism of CFST latticed members subjected to cyclic loadings, such as the law of displacement development of the limbs and lacings, the stress and strain distribution law of the limbs, lacings and connection between them, the failure mode of the latticed member, etc., will be comprehensively revealed, and the failure criterion under cyclic loadings and the seismic design principle and method of such composite latticed members will be established. The restoring force model for elasto-plastic seismic response analysis of structures with CFST latticed member will also be proposed.

由于主要受力的肢杆远离截面形心轴，格构式钢管混凝土构件具有较大的截面惯性矩，与同等条件下的单肢钢管混凝土构件相比，其自重更轻、轴向稳定性更好、抗弯刚度更大。实际工程中，当构件的荷载偏心率或长细比较大时，可采用格构式钢管混凝土构件，如工业厂房柱、栈桥柱、高桥墩和拱桥拱肋等。深入研究格构式钢管混凝土构件的滞回性能，是合理评估该类构件地震损伤演化规律，进而制定其合理抗震设计方法的重要前提。本项目拟理论和试验研究格构式钢管混凝土构件的滞回性能，基于非线性有限元理论和材料弹塑性本构关系建立理论模型，并利用典型构件及其节点的试验结果验证分析理论和模型。通过本项目的实施，将全面揭示反复荷载作用下格构式钢管混凝土构件的肢杆和缀件位移发展规律，肢杆、缀件及其节点区应力应变分布规律及失效模式等工作机理，确立其破坏准则及抗震设计原则与方法，提出可用于结构弹塑性地震反应分析的格构式钢管混凝土构件的恢复力模型。

格构式钢管混凝土构件由钢管混凝土肢杆和钢缀件组成，其通过肢杆与缀件的合理布置使主要受力的肢杆远离截面形心轴。与具有相同承载力的单肢钢管混凝土构件相比，其自重更轻、抗弯刚度更大，更适用于荷载偏心率或长细比较大的受力工况，如工业厂房柱、设备构架柱、桥塔、拱桥拱肋及风力发电塔或输电塔等，当这些构件或结构处于地震区时，需对其进行抗震性能评估及有效抗震设计。因此，深入研究地震作用下格构式钢管混凝土构件的力学性能，合理评估该类构件的地震损伤演化规律，并基于此确定其抗震设计原则与方法具有重要的科学意义和实用价值。本项目通过试验测定和有限元模拟相结合的方法，对格构式钢管混凝土构件的滞回性能及抗震设计方法进行了系统深入的研究，构件的肢杆为圆形或方形钢管混凝土、缀件为圆钢管。完成了恒定轴压力和低周反复荷载共同作用下典型格构式构件的试验研究，揭示了肢杆钢管径/宽厚比和轴压比对格构钢管混凝土构件滞回性能的影响规律；完成了钢管混凝土弦杆-钢管腹杆T形节点静力性能的试验研究。利用ABAQUS软件中考虑延性损伤的钢材弹塑性混合强化模型和考虑损伤退化的混凝土塑性损伤模型建立了力学性能分析的有限元模型，实现了对格构式钢管混凝土构件和组合T形节点损伤破坏过程的精细模拟，模拟结果与本项目及文献试验结果吻合良好。利用有限元模型进一步揭示了反复荷载作用下格构式钢管混凝土构件的肢杆和缀件位移发展规律，肢杆、缀件及其节点区应力应变分布规律及失效模式等机理，厘清了主要参数对格构式钢管混凝土构件荷载-变形滞回曲线骨架线和加卸载路径的影响规律，提出了压-弯-剪复合作用下格构式钢管混凝土构件和组合T形节点的承载力计算方法，为建立格构式钢管混凝土构件的恢复力模型打下了坚实基础。项目资助以来，项目组成员发表期刊论文10篇（SCI收录8篇、EI收录2篇），获国家自然科学奖二等奖1项，参编标准3部，培养博士研究生2名、硕士研究生4名。