常温及火灾后轻骨料钢管混凝土柱的轴压力学性能研究
发布时间：2019-02-25 11:45
【摘要】：目前国内外对普通钢管混凝土柱的抗火性能开展了较多的研究，而对轻骨料钢管混凝土柱火灾行为的研究还比较少，尤其对自应力及钢纤维增强轻骨料钢管混凝土柱的火灾响应及火灾后力学性能的研究更加薄弱。本文以页岩陶粒做为粗骨料，通过在混凝土中分别掺入一定量的膨胀剂和钢纤维制作了两种不同性质的轻骨料钢管混凝土柱，并以此为对象开展了一系列轻骨料钢管混凝土柱的抗火性能研究。由于钢纤维的加入可有效抑制核心混凝土微裂缝的发展，改善轻骨料钢管混凝土的力学性能；而膨胀剂的加入可在一定程度上提高轻骨料混凝土刚度较低的问题。因此，对自应力及钢纤维增强轻骨料钢管混凝土力学性能的研究具有重要的理论意义和工程应用价值。 本文首先以含钢率和膨胀剂掺量为变化参数对9组钢管约束下的自应力轻骨料混凝土的膨胀性能进行了试验研究。在此基础上，，对6个自应力轻骨料钢管混凝土中长柱开展了承载下的火灾响应及火灾后轴压力学性能试验研究，并用Marc有限元软件对其火灾下的温度场进行了模拟。为了对比分析，制作了18个自应力轻骨料钢管混凝土短柱和24个钢纤维增强轻骨料钢管混凝土短柱，并分别开展了常温及火灾后轴压力学性能的试验研究。其中受火条件考虑了700℃受火（1.5h）和900℃受火（1.5h）两种情况。基于试验结果，对各组钢纤维轻骨料钢管混凝土柱及自应力轻骨料钢管混凝土柱的实验现象、破坏形态进行了观测与分析。得到了各组试件受火后的荷载-位移曲线及荷载-应变曲线，分析了各个参数对火灾后自应力轻骨料钢管混凝土柱及钢纤维轻骨料钢管混凝土柱的承载能力和变形能力的影响。同时对试件常温下的极限承载力及火灾后的剩余承载力进行了分析比较。 试验结果表明，在轴压力作用下的自应力轻骨料钢管混凝土中长柱火灾后剩余承载力下降幅度与无荷载作用的轻骨料钢管混凝土短柱火灾后剩余承载力下降幅度相差不大。轻骨料钢管混凝土柱火灾后轴压破坏形态与常温下的情况基本一致。根据常温试件和火灾后试件的试验结果，钢纤维的掺量和膨胀剂的掺量对轻骨料钢管混凝土短柱承载力均有一定的影响。随着试件含钢率的增加，钢纤维和膨胀剂的增强效果逐渐减弱。初始自应力和钢纤维掺量对火灾后轻骨料钢管混凝土柱的承载力提高作用效果随火灾温度的升高而降低。根据试验结果，进一步分析了火灾温度对剩余承载力的影响规律，并基于普通钢管混凝土设计规程，提出了考虑自应力影响的轻骨料钢管混凝土短柱承载力计算方法。给出了考虑含钢率影响的钢纤维轻骨料钢管混凝土短柱承载力修正系数，经修正后的公式可用于常温下钢纤维轻骨料钢管混凝土柱承载力计算。
[Abstract]:At present, many researches have been carried out on the fire resistance of ordinary concrete-filled steel tubular columns at home and abroad, but less on the fire behavior of concrete filled steel tubular columns with light aggregate. Especially, the research on fire response and post-fire mechanical properties of steel fiber reinforced lightweight aggregate concrete filled steel tube columns is weaker. In this paper, two kinds of lightweight aggregate concrete filled steel tube columns with different properties were made by adding a certain amount of expansive agent and steel fiber into concrete with shale ceramsite as coarse aggregate. A series of light aggregate concrete filled steel tube columns are studied on the fire resistance of concrete filled steel tube columns. The addition of steel fiber can effectively restrain the development of micro-cracks in core concrete and improve the mechanical properties of lightweight aggregate concrete filled with steel tube, while the addition of expansive agent can improve the stiffness of lightweight aggregate concrete to a certain extent. Therefore, the research on self-stress and mechanical properties of steel fiber reinforced lightweight aggregate concrete filled steel tube has important theoretical significance and engineering application value. In this paper, the expansion behavior of self-stressed lightweight aggregate concrete under steel pipe restraint is studied by using the steel content and the content of expansive agent as the varying parameters. On this basis, the fire response and axial compressive mechanical properties of six medium length columns with self-stressed lightweight concrete-filled steel tube (CFST) under load are studied. The temperature field under fire is simulated by Marc finite element software. In order to compare and analyze, 18 self-stressed lightweight concrete filled steel tube columns and 24 steel fiber reinforced lightweight concrete filled steel tube columns were made, and the mechanical properties of axial compression at room temperature and after fire were studied respectively. The fire conditions include 700 鈩
本文编号：2430126
[Abstract]:At present, many researches have been carried out on the fire resistance of ordinary concrete-filled steel tubular columns at home and abroad, but less on the fire behavior of concrete filled steel tubular columns with light aggregate. Especially, the research on fire response and post-fire mechanical properties of steel fiber reinforced lightweight aggregate concrete filled steel tube columns is weaker. In this paper, two kinds of lightweight aggregate concrete filled steel tube columns with different properties were made by adding a certain amount of expansive agent and steel fiber into concrete with shale ceramsite as coarse aggregate. A series of light aggregate concrete filled steel tube columns are studied on the fire resistance of concrete filled steel tube columns. The addition of steel fiber can effectively restrain the development of micro-cracks in core concrete and improve the mechanical properties of lightweight aggregate concrete filled with steel tube, while the addition of expansive agent can improve the stiffness of lightweight aggregate concrete to a certain extent. Therefore, the research on self-stress and mechanical properties of steel fiber reinforced lightweight aggregate concrete filled steel tube has important theoretical significance and engineering application value. In this paper, the expansion behavior of self-stressed lightweight aggregate concrete under steel pipe restraint is studied by using the steel content and the content of expansive agent as the varying parameters. On this basis, the fire response and axial compressive mechanical properties of six medium length columns with self-stressed lightweight concrete-filled steel tube (CFST) under load are studied. The temperature field under fire is simulated by Marc finite element software. In order to compare and analyze, 18 self-stressed lightweight concrete filled steel tube columns and 24 steel fiber reinforced lightweight concrete filled steel tube columns were made, and the mechanical properties of axial compression at room temperature and after fire were studied respectively. The fire conditions include 700 鈩
本文编号：2430126
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