FRP管约束十字形钢骨混凝土柱的力学性能与设计方法

以处于恶劣腐蚀环境下的FRP管约束十字形钢骨混凝土桥墩柱为研究对象，对其力学性能和设计方法进行系统深入的试验研究、数值模拟和理论分析。首先以FRP管约束十字形钢骨混凝土柱的轴压性能试验与三维有限元模拟分析为切入点，揭示FRP管、混凝土及十字形钢骨之间的相互作用机理，提出FRP管约束十字形钢骨混凝土滞回本构关系模型，建立轴压承载力公式；在此基础上进行FRP管约束十字形钢骨混凝土柱的偏压性能试验与分析，系统研究偏心距、长细比等对柱偏压性能的影响，得到组合柱的轴力-弯矩（N-M）相关曲线，提出长柱承载力稳定系数，建立偏压承载力计算公式；最后进行FRP管约束十字形钢骨混凝土柱的抗震性能试验与分析，明确轴压比、剪跨比、地震作用方向和FRP管约束强度等对组合柱抗震性能的影响规律，建立FRP管约束十字形钢骨混凝土柱的水平抗剪承载力、极限位移角和荷载-位移恢复力模型，提出实用抗震设计方法。

The mechanical behavior and design method of a novel type of FRP tube-confined concrete-encased cross-shaped steel columns (FCCSCs) is investigated experimentally, numerically and theoretically. The columns can be used as bridge piers under severe corrosive environment. Firstly, the experimental study and 3D finite element analysis on FCCSCs subjected to axial compression load have been chosen as breakthrough point to reveal the interaction mechanism among the FRP tube, concrete and cross-shaped steel. Based on the test and analysis results, the cyclic stress-strain model and axially compressed bearing capacity equation for FCCSCs is proposed. Then, the eccentric compression behavior of FCCSCs are investigated experimentally and analytically. The influence of load eccentricities and slenderness ratio on the eccentric compression behavior of composite columns are investigated systematically. On the basis, the N-M interaction diagram, stability coefficient, and ultimate bearing capacity equation of eccentrically compressed FCCSCs are proposed. Finally, the seismic performance of FCCSCs are investigated experimentally and analytically. The influence of axial compression ratio, shear span ratio, seismic load direction and FRP tube confined stress on the seismic performance of FCCSCs are verified. The shear capacity, ultimate drift ratio and lateral load-displacement hysteretic model of FCCSCs are then proposed. The seismic design method for FCCSCs is developed through the above investigations.