Dynamic performance characteristics of an innovative Cable Supported Beam Structure-Concrete Slab Composite Floor System under human-induced loads

An innovative Cable Supported Beam Structure-Concrete Slab Composite Floor System (CSBS-CSCFS) with a desirable large span capacity was developed in this study to meet the large interior space requirement of public buildings. This new system has excellent merits over conventional floor structures, particularly in terms of span capacity, strength-to-weight ratio, and thin-walled floor. Despite awareness of these advantages, this type of system is not fully utilized because of the potential disadvantage of excessive vibration under human-induced loads. To investigate the dynamic behavior of this system under human-induced loads, field tests were conducted on the floor of the recently built Hebei Normal University Gymnasium, to which the CSBS-CSCFS was applied for the first time. Two types of experimental tests were conducted: free and human-induced vibration tests, in which the vertical acceleration responses of the floor structure were measured under several types of human-induced loads (e.g., stepping, jumping, walking, running, and random activities). Human perception of vibration during the tests was also determined through questionnaires. Results of the free vibration tests showed that the first three natural frequencies of the structure are 2.30 Hz, 2.69 Hz and 3.06 Hz. Moreover, the floor has a damping ratio with a value of 1.54%. This result implies that the structure has relatively low natural frequencies, and its performance may be affected by human activities. Results of human-induced vibration tests indicated that the human-induced vibration of the CSBS-CSCFS is influenced by several factors, namely, dynamic characteristics of the structure, type of human-induced load, stationary people occupying the floor, synchronism of activities, crowd size, and load frequency. The dynamic responses of the structure were compared with International Organization for Standardization (ISO) and American Institute of Steel Construction (AISC) criteria. Meanwhile, human perception of vibration was also summarized. The comparison and summary implied that the vibration of the floor should be attenuated to improve human comfort, although doing so is unnecessary in normal usage. A passive dynamic control system is an efficient method to achieve this goal.