Vibration serviceability assessment of stadium grandstands
Annoying vibrations in grandstand structures have been getting more attention due to the increasing slenderness of the architectural components and the complexity of the crowd loading for engineers. The vibration serviceability checks under these conditions become a challenge in the design and operation stages. Although durations of excessive vibrations have been considered as one of the most important factors affecting occupants’ comfort, incorporating the vibration duration in the occupant comfort analysis has not been addressed yet. In addition, the currently available approaches using raw acceleration, weighted root mean square (RMS) acceleration, vibration dose values (VDV), etc. may not always be sufficient for serviceability assessment due to the lack of guided procedure for calculating the integration time and implementing the duration of vibration into the process. Therefore, in this current study, a new parameter and framework are proposed for assessing human comfort where the duration of vibration is incorporated with conventional data processing.
Description of the stadium
The stadium was opened to service in 2007. It is supported by steel frames and has the capacity of 45,000 seats. The stadium contains 38 lower-level and 36 upper-level sections.
Description of the stadium
The stadium was opened to service in 2007. It is supported by steel frames and has the capacity of 45,000 seats. The stadium contains 38 lower-level and 36 upper-level sections.
Fig. 1. The stadium and its investigated section
Twelve accelerometers were used, eight of which were installed in the upper section while the remaining accelerometers were used in the lower section (Fig. 2)
Fig. 2. Sensor locations
The proposed Area of RMS (ARMS) method
Available standards and related research provide useful tools; however, their capabilities for evaluating the vibration levels and predicting occupant response are still arguable. In addition, durations of uncontrolled vibrations were not appropriately addressed in these standards and research studies. Based on this, in this current study, a new parameter and a new framework are proposed to comprehensively evaluate the vibration levels and the corresponding levels of human comfort in stadiums by employing the lengths of excessive vibrations and the recommended frequency weighting functions. The proposed value is called the Area of RMS (ARMS) and is calculated by the following equation [1].
Available standards and related research provide useful tools; however, their capabilities for evaluating the vibration levels and predicting occupant response are still arguable. In addition, durations of uncontrolled vibrations were not appropriately addressed in these standards and research studies. Based on this, in this current study, a new parameter and a new framework are proposed to comprehensively evaluate the vibration levels and the corresponding levels of human comfort in stadiums by employing the lengths of excessive vibrations and the recommended frequency weighting functions. The proposed value is called the Area of RMS (ARMS) and is calculated by the following equation [1].
Human comfort levels
After defining the proposed ARMS value for assessing the human comfort, the next critical step is to define the limits for differentiating different comfort levels using the proposed ARMS value.
After defining the proposed ARMS value for assessing the human comfort, the next critical step is to define the limits for differentiating different comfort levels using the proposed ARMS value.
Table 1. ARMS range and corresponding likely reactions [1]
Data Analysis and results
The below acceleration plot (Fig. 3) shows some events due to the audience’s activities, i.e. interception, touchdown and playing the popular song.
The below acceleration plot (Fig. 3) shows some events due to the audience’s activities, i.e. interception, touchdown and playing the popular song.
Fig. 3. Typical vibration data [1]
The ARMS results from this channel are shown in Table 2. Overall, there are five events that caused the most excessive vibrations in the stadium, i.e. touchdown, kickoff, interception, stamping and popular song. The structure vibrated differently during each event with the duration varying from 19 to 50 s. The corresponding human comfort levels are also estimated. Note that “Disturbing” was found only at some distinctly vibrating events with long periods.
Table 2. Analysis of data recorded at Channel 11
Reference
- Do, N. T., Gül, M., Abdeljaber, O., Avci, O. (2018) “Novel Framework for Vibration Serviceability Assessment of Stadium Grandstands Considering Durations of Vibrations,” Journal of Structural Engineering, ASCE, Vol 22, No. 2, 04017214.
