火灾作用下钢异形柱局部稳定性能的研究

发布时间：2018-07-22 20:55

【摘要】：对钢异形柱而言，兼备了承载能力高、截面小、抗震性能好、建筑美观等优点，但与型钢混凝土异形柱相比，失去混凝土保护的钢材，在火灾作用下其强度、弹性模量等基本力学性能指标急剧下降，加之钢异形柱是截面不规则的开口薄壁杆件，受火面积大，较传统的轧制型钢柱而言，钢异形柱的抗火性能更应值得关注。钢异形柱是该结构体系主要的承重构件，钢异形柱的稳定性能直接决定了建筑的安全性，钢异形柱的失稳方式有整体失稳和局部失稳，要想发挥钢异形柱的最佳力学性能，就要确保钢异形柱在发生整体失稳之前不发生局部屈曲，因此，控制好影响钢异形柱局部稳定的因素，对整个建筑的安全至关重要。针对上述因素，本文通过对9根H型截面钢柱进行火灾试验、数值模拟分析来研究其在火灾下的局部稳定性能。常温下钢材的物理性质及力学性能较为稳定，在进行构件加工前预留出三种不同厚度钢板的“狗骨”试件，进行拉伸试验得到钢材的屈服强度fy、弹性模量E等主要力学性能指标，以便计算得到高温下钢材的主要力学性能指标进行理论计算。焊接残余应力作为主要初始缺陷对H型截面钢柱的影响不可忽略，且其分布规律与板件尺寸有关，因此有必要测试本批次构件焊接残余应力的分布规律，以便使数值模拟分析结果更具真实性，在构件加工过程中，采用相同工艺加工3根H型截面钢柱用于焊接残余应力的测试。对9根H型截面钢柱进行受火试验，试验前对构件施加一定初始荷载，并在整个过程中维持不变。在整个受火过程中时刻观察并记录构件的试验现象，测试板件的变形量、构件的轴向变形及水平火灾炉与板件自身的升温变化规律。Z1~Z3腹板温度升高速度及变形增加速度均大于翼缘板，腹板先于翼缘板屈曲；Z4~Z6翼缘板温度升高速度及变形增加速度均大于腹板，翼缘板先于腹板屈曲；Z7~Z9翼缘板及腹板并未同时发生屈曲且板件屈曲的顺序不确定。利用ANSYS对与试验相同尺寸的9根H型截面钢柱进行有限元模拟，，将所得数据与试验数据进行对比，得到H型截面钢柱在火灾下的局部稳定性能。通过分析数据得到高温下H型截面钢柱发生局部屈曲时，其翼缘板及腹板之间相互嵌固作用系数ξ及受均匀荷载作用下的薄壁板件在高温下的弹性屈曲应力计算公式。
[Abstract]:For steel special-shaped columns, they have the advantages of high bearing capacity, small cross-section, good seismic performance, beautiful buildings, etc. But compared with SRC special-shaped columns, the steel without concrete protection has the strength under fire. The basic mechanical properties such as modulus of elasticity decrease sharply, and the steel special-shaped column is a thin-walled member with irregular section, which has a large area of fire. Compared with the traditional rolled steel column, the fire resistance of the special-shaped steel column should be paid more attention to. The steel special-shaped column is the main load-bearing member of the structure system. The stability performance of the steel special-shaped column directly determines the safety of the building. The instability mode of the steel special-shaped column has the integral instability and the local instability. In order to give full play to the optimum mechanical properties of the steel special-shaped column, It is necessary to ensure that the local buckling of steel special-shaped columns does not occur before the whole instability occurs. Therefore, it is very important for the safety of the whole building to control the factors that affect the local stability of the steel special-shaped columns. In view of the above factors, the local stability of 9 H-section steel columns under fire was studied by numerical simulation and numerical simulation. The physical properties and mechanical properties of steel at room temperature are relatively stable. Three kinds of "dog bone" specimens with different thickness steel plates are reserved before the processing of the components. The main mechanical properties of steel, such as yield strength, elastic modulus E and so on, are obtained by tensile test, so that the main mechanical properties of steel at high temperature can be calculated theoretically. The influence of welding residual stress as the main initial defect on H-section steel column can not be ignored, and its distribution law is related to the size of plate, so it is necessary to test the distribution law of welding residual stress in this batch. In order to make the results of numerical simulation analysis more authentic, three H-section steel columns were processed in the same process to measure the welding residual stress. Nine H-section steel columns were subjected to fire tests, and the initial loads were applied to the members before the test, and remained unchanged during the whole process. Observe and record the experimental phenomena of the components at all times during the whole process of fire, and test the deformation of the plates, The axial deformation of the component and the variation of the temperature of the horizontal fire furnace and the plate. The increasing speed of the temperature and deformation of the web is higher than that of the flange plate, and the web is buckling before the flange plate. The increasing velocity of temperature and deformation of Z4 / Z6 flange plate is higher than that of web plate. The flange plate does not buckle at the same time as the web plate and the flange plate and web plate are not buckled at the same time, and the order of buckling of the flange plate is uncertain. The finite element simulation of 9 H-section steel columns with the same size as the test is carried out by ANSYS. The local stability of H-section steel columns under fire is obtained by comparing the obtained data with the experimental data. By analyzing the data, the formulas for calculating the elastic buckling stress of thin-walled plates subjected to uniform load are obtained when the local buckling of H-section steel columns occurs at high temperature.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU391

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