冷弯薄壁型钢-混凝土组合楼盖基频研究

STUDY ON FUNDAMENTAL FREQUENCY OF COLD-FORMED STEEL CONCRETE COMPOSITE FLOOR

首先对构造不同的4个足尺比例冷弯薄壁型钢-混凝土组合楼盖模型进行了动载试验。在正常使用阶段,研究了压型钢板与冷弯薄壁型钢梁连接的螺钉间距、刚性支撑件、楼盖端部约束构造设置和楼面活荷载对组合楼盖基频的影响;其次采用ANSYS有限元程序对试验模型16种荷载工况的基频进行模拟,验证了有限元分析方法的可行性;接着利用有限元对组合楼盖基频影响因素进行了分析;最后提出了预测楼盖基频的理论公式。研究表明:组合楼盖的基频随楼面活荷载的增加而降低;压型钢板与楼盖梁连接的螺钉间距、楼盖梁间距、跨高比、腹板高厚比的减小和加强楼盖端部约束、增大楼盖梁及混凝土翼板厚度、相邻楼盖梁跨中设置刚性支撑件均能够提高组合楼盖的基频;而改变压型钢板板型和楼盖宽度对基频影响很小;提出的理论公式能够较好地预测组合楼盖基频。

The dynamic tests are carried out for 4 full scale models of cold-formed steel joists composite floors with different patterns of configuration. At a serviceability limit stage, effects to the fundamental frequency were studied, when the space among screws connect the roll-profiled steel sheet and the cold-formed steel joists was changed, or the rigid blocking, end constraints, floor live loads were different. By simulating the fundamental frequency of 16 different load cases using the finite element program based on ANSYS, the feasibility of the finite element method was approved. The factors which affect the fundamental frequency were analyzed through the finite element method, and a theoretical formula forecasting the fundamental frequency is then suggested. The research shows that the fundamental frequency declines with the increase of the live load of the floor, and that it can be improved by shortening the space among screws connecting the roll-profiled steel sheet and joists, by reducing the span depth ratio of floor joists or the width-thickness ratio of web, by setting rigid blockings at mid-span of adjacent joists, by strengthening the floor end constraints, and by increasing the thichness of joist or concrete slabs. The change of roll-profiled steel sheet shapes and the width of the floor bring little effect to the fundamental frequency. And the theoretical formula forecasting the fundamental frequency works well.