排练厅大跨度楼盖结构振动舒适度设计

Vibration Comfort Design for Structure of Large-Span Floor System in Rehearsal Room

随着社会经济的发展和人民生活水平的提高,大跨度楼盖建筑得到发展。楼盖结构的竖向自振频率越来越接近人员活动的激励荷载频率,导致结构产生影响舒适度的动力响应,因此建筑楼盖中的振动舒适性问题开始引起人们的重视。舒适度问题需要在结构设计阶段考虑,如果在工程竣工后才发现楼盖结构的振动舒适度问题,则后期加固难度大、代价高。以排练厅大跨度楼盖结构为工程背景,由于大跨度楼盖结构的第1阶整体竖向振型的频率较低,与排练厅使用人员产生的振动荷载频率接近,楼盖容易产生影响舒适性的动力响应。故按照国家现行标准JGJ/T 441—2019《建筑楼盖结构振动舒适度技术标准》在结构设计阶段对排练厅大跨度楼盖结构进行振动舒适度控制。首先,通过模态分析确定楼盖的动力特性、最不利振动点的位置以及激励荷载的时程曲线。然后,通过动力响应分析对各个振动荷载工况进行舒适度评价,并确定了排练厅楼盖振动舒适度的控制工况。当不采取减振措施时,在人群跳舞激励的控制工况下,楼盖最不利振动点处的稳态振动峰值加速度高达1.047 m/s~2,跳舞人群会明显感觉到不舒适。最后,采用调谐质量阻尼器对楼盖进行减振设计,确定质量、阻尼比和频率比对减振率的影响规律,并成功将舒适度控制工况下楼盖最不利振动点处的稳态振动峰值加速度降低至0.483 7 m/s~2(在规范限值之内),减振率为53.8%,满足了跳舞人群对楼盖振动舒适度的要求。

With the development of social economy and the improvement of people’s living standard,the building with large-span floor has gradually developed.The vertical natural vibration frequency of floor structures is getting closer to the load frequency of human activities,which may generate dynamic response affecting comfort.Therefore,the vibration comfort problem in the building floor has begun to attract people’s attention.The comfort problem needs to be considered in the structural design stage.If the vibration comfort problem of the floor structure is found after the completion of the project,it is difficult and costly to strengthen.In this paper,the structure of large-span floor system in rehearsal room was taken as the engineering background,The frequency of the first order overall vertical mode of the large-span floor structure is low,which is close to the vibration load frequency generated by the users of the rehearsal hall,and the floor is prone to produce dynamic responses that affect comfort.Therefore,the vibration comfort control was conducted in the structural design stage for the large-span floor structure of the rehearsal hall,according to the current national standard JGJ/T 441-2019 Technical Standard for Human Comfort of the Floor Vibration.Firstly,through modal analysis,the dynamic characteristics of the floor system,the location of the maximum vibration point and the time history curves of the excitation loads were determined.Secondly,through dynamic response analysis,the comfort of various vibration load conditions was evaluated,and the controlling vibration load condition for the comfort of the floor system in rehearsal room was determined.When no vibration reduction measures are taken,under the control condition of crowd dancing excitation,the steady-state peak acceleration of the most unfavorable vibration point of the floor is as high as 1.047 m/s 2,and the dancers will obviously feel uncomfortable.Lastly,the vibration reduction design for the floor system was conducted by means of tuned mass damper(TMD).The influence of TMD’s mass,damping ratio and frequency ratio on the vibration reduction ratio was studied.The peak acceleration of the maximum vibration point of the floor system during the steady-state vibration stage was successfully controlled to 0.4837 m/s 2(within the limit of standard),and the vibration reduction rate is 53.8%,which meets the requirements of the dancing crowd for comfort.