含钢率对GFRP管-钢骨混凝土组合构件抗冲击性能的影响

为了研究含钢率对GFRP（glass fiber reinforced polymer）管-钢骨混凝土组合构件抗冲击性能的影响，建立15个组合构件的数值模型，在验证模型正确的基础上，通过分析典型构件的冲击全过程、截面弯矩发展以及破坏时应变分布规律，研究构件在侧向冲击荷载作用下的破坏模式；通过分析构件冲击力时程曲线、侧移时程曲线以及能量变化情况，探究含钢率对不同长细比构件抗冲击性能的影响。结果表明：与未配置钢骨的构件相比，GFRP管-钢骨混凝土构件的抗冲击承载力提高了7%~134%，侧向位移减小了13%~68%。在侧向冲击荷载作用下，构件的破坏模式以弯曲破坏为主，同时伴随着GFRP管和混凝土冲击区域的局部破坏，抗弯刚度是影响构件抗冲击性能的主要因素之一。构件的抗冲击承载力随着含钢率的增高而提高，随着构件长细比的增大而降低。含钢率相差1.5%时，截面惯性矩较大的窄翼缘型钢对构件的抗冲击性能更有利。对于长细比大于20的构件，钢骨耗能是组合构件总能耗的主要组成部分。

Effect of steel ratio on the impact resistance of GFRP tube concrete-encased steel composite members

To investigate the effect of the steel ratio on the impact resistance of glass fiber reinforced polymer (GFRP) tube concrete-encased steel composite members, 15 numerical models of composite members were established. The whole impact process, the dynamic response and the stress distribution of each composite member at different characteristic moments during the low-velocity impact were analyzed. The bending moment contributions at typical cross sections and the energy dissipation under different impact moments were explored. Meanwhile, the corresponding failure mode was determined, based on the maximum principal plastic strain distribution of concrete, tensile and compression damage of GFRP tube matrix, and equivalent plastic strain distribution of steel. Additionally, the effect of the steel ratio on the impact performance of members with different slenderness ratios was investigated by analyzing the time history curves of the impact force, displacement, energy transformation and energy consumption. The results show that the impact load-bearing capacity of GFRP tube concrete-encased steel members is improved by 7% to 134% and the lateral displacement is reduced by 13% to 68% compared with the GFRP tube concrete members. Furthermore, it can be observed that the failure mode of the members is mainly bending, and the concrete is crushed in the impact region. The bending stiffness has a significant influence on the impact performance of the member under lateral impact loading. The impact force of the member increases with the increase in the steel ratio, whereas the impact force of the member decreases with the increase in the slenderness ratio. Moreover, narrow flange steel with a higher moment of inertia is more favorable for the impact resistance of the member when the difference in steel ratio is 1.5%. The energy consumption of the encased steel is a major contributor to the total energy consumption of the member when the slenderness ratio is greater than or equal to 20. The GFRP tube plays a dual role in bearing the impact force and confining the concrete in a circumferential direction at the oscillation stage during the impact process.