大跨度楼盖步行荷载作用的加速度反应谱研究

基于61人次2 204条实测的步行荷载曲线，提出了计算单人步行竖向荷载作用下大跨度楼盖加速度均方根响应的反应谱。以42m跨矩形板为研究对象，首先得到每条实测步行荷载的反应谱，在此基础上建立设计反应谱的分段表达式：对应于步行1阶主频范围的第1平台段（1.5~2.5Hz）、对应于步行2阶主频范围的第2平台段（3~5 Hz），以及对应于步行高阶频率的曲线下降段（5~10 Hz）。给出了2个平台段不同保证率的代表值计算方法和下降段的数学表达式。进一步研究了高阶振型、边界条件、计算跨度等因素对反应谱的影响，并给出了对应的修正方法。给出了建议反应谱的使用步骤，并应用于4个实际楼盖结构。对比分析表明，楼盖的实测响应接近或略大于反应谱75%保证率的计算结果，但均小于95%保证率下的计算结果，所建议的反映谱方法可用于计算单人步行荷载作用下大跨楼盖的加速度响应。

Acceleration response spectrum for predicting floor vibration due to occupant walking

Based on 2 204 experimentally measured footfall traces from 61 test subjects, the design-oriented acceleration response spectrum was studied for calculating a floor’s response due to occupant walking. Taking a rectangular floor with 42m span as the object, the corresponding 10-second peak root-mean-square acceleration response spectrums were generated, on which a piece-wise mathematical model was proposed. The proposed response spectrum model consisted mainly three parts: the first resonant plateau ranging from 1.5 Hz to 2.5 Hz, the second resonant plateau ranging from 3.0 Hz to 5.0 Hz and the descending part ranging from 5.0 Hz to 10.0 Hz. The representing value of each plateau and the descending curve were statistically determined for different confidence levels. Furthermore, the effects of factors such as floor span, occupant’s stride length, higher modes of vibration, boundary conditions and different assessment quantities on the proposed spectrum were investigated. Accordingly, the modification measure for each factor was suggested. Detailed application procedure for the proposed spectrum approach was presented and it was applied to four existing floors to predict the acceleration responses. Comparison shows that the measured acceleration responses of the four floors are generally close to the predicted results with 75% confidence level and are all lower than the predicted results with 95% confidence level. The suggested spectrum-based approach can be used for predicting a floor’s response under single person’s walking.