考虑楼板影响的结构竖向加速度响应

Vertical acceleration response of structure considering the influence of floor slab

摘要:

除了水平地震作用,竖向地震动亦显著影响吊顶等非结构构件的破坏状态,而当前有关结构在竖向地震动作用下的竖向加速度响应研究还不充分。为此,以某包含不同尺寸楼板的实际框架结构为例,进行结构竖向振型分析,开展4类共80条地震动作用下的时程分析,研究结构竖向加速度响应及其影响因素,并拟合了可供非结构构件抗震分析的标准化竖向设计反应谱。结果表明:楼层竖向加速度放大系数范围主要在1.21~8.16,远大于各国规范对水平向放大系数的规定；结构的竖向加速度响应与楼板自振频率、竖向地震动卓越频率、楼层高度以及楼层中楼板上位置有关,结构竖向响应可能存在由结构竖向柔性导致的明显放大现象,其对非结构构件存在不利影响；得到了结构竖向加速度标准化设计谱曲线和数学表达方式,可更好地用于非结构构件的抗震分析。

Abstract:

In addition to horizontal seismic actions, vertical ground motion also significantly affects the damage state of non-structural components such as suspended ceilings. However, there is currently insufficient research on the vertical acceleration response of structures under vertical ground motion. To address this gap, a case study is conducted using a real frame structure with different-sized floor slabs. This study performs vertical mode analysis of the structure and conducts time history analyses under four categories of seismic motions, totaling 80 records. The vertical acceleration response of the structure and its influencing factors are studied, and a standardized vertical design response spectrum for seismic analysis of non-structural components is fitted. The results show that the vertical peak floor acceleration amplification factor for the floors range from 1.21 to 8.16, which is much higher than the horizontal amplification factors specified in various national standards. The vertical acceleration response of the structure is influenced by the self-vibration frequency of slabs, the dominant frequency of vertical ground motions, the height of the floors and the position of slabs within the floors. The vertical response of the structure may be amplified significantly due to the vertical flexibility of the structure, which have obvious adverse effects on non-structural components. Additionally, a standardized design spectrum and mathematical expression for vertical acceleration of the structure are obtained, which can be better used for the seismic analysis of non-structural components.