摘要
人行天桥的结构设计中影响行人舒适度的动力特性指标主要有自振频率和受激励时的振动加速度,但实测数据较少。以北京21座正在使用中的人行桥为调查对象,对人行桥进行加速度时程测量的同时,随机对通行行人进行关于通行舒适度的问卷调查,共获得1 053份调查问卷。还在无行人干扰的情况下,对各人行桥进行了多种行人工况下的动力反应实测。通过对实测数据的分析,研究了行人激励下最大加速度与均方根加速度的相关关系、单人行走激励反应与人群行走激励反应的关系、人行桥自振频率与跨度的关系。结合问卷调查结果,定义了行人有感系数和舒适度系数,分别研究了这两个定量化的振动舒适度指标与自振频率的相关关系和与峰值加速度的相关关系。研究发现,这两个指标与人行桥一阶竖向自振频率相关性并不强,而与峰值加速度间有较明确对应关系,并拟合得到了有感系数-峰值加速度相关曲线和舒适度系数-峰值加速度相关曲线。从而可对人行天桥的振动舒适程度进行定量表达,并与结构的加速度反应建立了对应关系。以上结果为人行桥的振动舒适性的基于性能设计提供了基础。
Although natural frequency and acceleration response are recognized as two main indices in footbridge design with respect to pedestrian＇s comfort level,supporting in-situ measurement data are actually limited.In view of this,twenty one inservice footbridges in Beijing are investigated in this study.The vibration acceleration time history of each bridge was recorded;meanwhile,randomly selected pedestrians were surveyed regarding their comfort feeling via questionnaire.A total of 1 053 valid questionnaire were collected.The dynamic responses of each footbridge were also measured under different pedestrian loading cases.The analyses of in-situ measurement data reveal the correlation between maximal acceleration and RMS acceleration,the correlation between dynamic response produced by single pedestrian and that by crowds,as well as the correlation between footbridge span length and natural vibration frequency.Combined with the information from questionnaire survey,two pedestrian＇s comfort level indices,termed felt fraction and comfortable fraction,are quantitatively defined,and their relations to natural frequency and maximal acceleration of footbridges are examined.It is demonstrated that the two factors have weak correlation to the first modal frequency in vertical direction,but have strong correlation to the maximal acceleration.The regression analyses of the felt fraction-maximal acceleration curve and the comfortable fraction-maximal acceleration curve provide a quantitative expression for pedestrians comfort level on footbridges and a mapping between pedestrian＇s comfort level and acceleration.These will be the basis of performance-based design for footbridge vibration in future.
出处
《振动工程学报》
EI
CSCD
北大核心
2013年第4期545-553,共9页
Journal of Vibration Engineering
基金
科技部国际合作项目(2010DFR50400)
973计划项目(2012CB026200)资助
关键词
人行天桥
自振频率
舒适度系数
峰值加速度
有感系数
foot bridge
natural frequency
comfort level index
maximal acceleration
felt fraction
