圆钢强化钢管混凝土梁正截面承载性能研究

Research on bearing capacity of normal section of concrete-filled steel tube beam reinforced with round steel

为探索拱腹焊接圆钢对钢管混凝土梁弯曲性能的提升效果,首先制备6根钢管混凝土梁,包括1根参考梁和5根不同直径圆钢加固的强化梁,并开展四点弯曲试验;在此基础上,提出圆钢强化钢管混凝土梁正截面的弯曲承载性能计算理论,并通过试验验证其合理性;然后,分析圆钢强化梁正截面中性轴偏移规律以及各部分对弯曲承载性能的贡献,揭示拱腹焊接圆钢对钢管混凝土梁弯曲性能的提升机制;最后,采用建立的计算理论开展参数敏感性分析。研究结果表明:拱腹焊接圆钢可以降低钢管混凝土梁正截面中性轴位置,显著提高钢管混凝土梁的抗弯承载力;随着焊接圆钢直径增大,钢管弯矩承载力基本保持不变,圆钢和管内混凝土弯矩承载力提高,但圆钢弯矩承载力的提高速率更快,因此,强化梁抗弯承载性能的提高主要得益于圆钢的抗弯承载性能;提高钢管和圆钢强度均可有效提高钢管混凝土梁的抗弯承载能力,但提高圆钢强度对抗弯承载力的提升效果更为明显。

In order to explore the effect of welding round steel at the soffit on the flexural behavior of concretefilled steel tube(CFST)beams,six specimens were firstly tested under four-point bending load,including a reference beam and five strengthened beams reinforced with round steel of different diameters.Then,the calculation theory of bending bearing capacity of the normal section of the strengthened CFST beams was proposed and validated by experimental results.The neutral axis offset of the normal section of the strengthened beams and the contribution of each part to the flexural bearing behavior were further analyzed,and the improvement mechanism of the round steel on the flexural behavior of the CFST beams was revealed.Finally,the parameter sensitivity analysis was carried out using the proposed calculation theory.The results show that the neutral axis of normal section of the strengthened beam moves downward caused by the welded round steel,and therefore the flexural bearing capacity of the CFST beams is significantly improved.As the diameter of the round steel increases,the flexural capacity of the steel tube remains basically unchanged,whereas the flexural capacity of the round steel and the core concrete increases,but the increase rate of flexural capacity of the round steel is more obvious.Therefore,the enhancement of the flexural capacity of the strengthened CFST beams mainly benefits from the flexural capacity of the round steel.The flexural capacity of the CFST beams can be effectively improved by increasing the strength of steel tube and round steel,but the effect of increasing the strength of round steel on flexural capacity is more obvious.