下部隔墙对木楼盖竖向振动性能的影响

Effects of stud partitions on the vertical vibration performances of metal plate connected timber floors

楼盖是水平方向分隔上下楼层空间的承重构件,是木结构建筑中不可缺少的一部分。但大跨度楼板阻尼小、柔性大、自振频率低,容易在人类活动与其他外界动力载荷作用下产生竖向振动,引起人们的不适;所以研究木楼盖的振动行为,找出提高振动舒适度的办法对大跨度木楼盖的推广和应用有重要作用。为了解大跨度木楼盖的振动性能,首先以12 m跨度齿板连接木桁架搁栅楼盖为研究对象,在其下部安置隔墙,比较不同支撑方式对楼盖振动模态、静载挠度、步行荷载响应与自由落体冲击响应的影响,并探讨隔墙位置和数量对木楼盖振动性能的影响规律。结果表明:下部隔墙对木楼盖振动性能的影响取决于连跨后的最大跨度。安装隔墙后,楼盖的基本自振频率提高25%以上,1 kN集中静态挠度减小40%以上;隔墙能有效降低最大跨度中央楼盖的步行振动响应,安装隔墙后楼盖步行均方根加速度减小30%以上;楼盖的振动传递主要发生在纵向,相同传递距离下纵向峰值加速度是横向和斜向的1.5倍以上。

Floor is a load-bearing component that separates the upper and lower floors in the horizontal direction and is an indispensable part of the wood structure building.Due to the small damping,large flexibility,and low natural frequency of the large-span floor,the timber floor is easy to induce vertical vibration under the human activities and other dynamic loads such as walking,running,and jumping compared to the conventional concrete floor,which causes the concern for the timber floor design in many cases.Therefore,the vibration behavior of timber floors play an important role in the promotion and application of long-span timber floors and it is desired to find a method to ease the annoying human-induced vibration.A field test of timber floors was carried out because it is difficult to predict the response due to loading for timber floors by existing theoretical formula or finite element models.A 12-m span metal plate connected timber truss joist floor was built and designed four different reinforcing methods with stud partitions in order to understand the vibration performance of the large-span wooden floor.The vibration response of floor was analyzed by the modal test,1-kN static deflection test,pedestrian load test and free fall impact load test.Effects of different stud partition installation schemes on the vibration performance of timber floor was discussed.It was observed that the effect of stud partition on the timber floor vibration performance depends on the maximum span in continuous span structure,that is,the maximum length between the walls perpendicular to the truss.After setting stud partition perpendicular to the joist,the first order natural vibration frequency was increased by more than 25%,and the 1-kN concentrated static deflection was reduced by more than 40%.The walking vibration response of the center of the maximum span reduced effectively by the stud partition.After setting the stud partition,the root mean square(RMS) acceleration was reduced by more than 30%.The vibration transmission of the floor cover mainly occurs in the longitudinal direction,and the longitudinal peak acceleration under the same transmission distance is 1.5 times more than that of the lateral and oblique directions.