Eliminates anxiety caused by wind sway in long, narrow commercial buildings!
Medium-to-high-rise buildings with long, narrow shapes with large aspect ratios tend to sway in the wind, causing occupants to feel uneasy and uncomfortable. By installing TMDs for horizontal vibration, occupant comfort is ensured without reducing the exclusive area.
issue
Taller buildings are more likely to sway in the wind, but wind sway can be a problem even in mid- to high-rise buildings of up to approximately 15 stories. Buildings that are built on narrow lots in urban areas are often slender and slender in shape, and are just as susceptible to wind as skyscrapers.
A certain commercial building had a very long and narrow shape with an aspect ratio of 5, so there were concerns about the building swaying due to strong winds (Table-1).
To avoid wasting as much exclusive area as possible, we decided to use horizontal TMDs, which are installed on the rooftop to prevent wind sway, instead of increasing the number of columns or making them larger.
Table 1: Building Summary
counter-measure
First, wind velocities were set based on the Building Load Guidelines for a reproduction period of one year, simulations were performed, and a preliminary evaluation was conducted using the Building Society of Japan's "Occupant Performance Evaluation Criteria". In the case of no countermeasures, the result was H-VI "rather uneasy and rather uncomfortable," and it was determined that this could be improved by installing vibration control measures.
A proposal to install a 10-ton TMD on the roof as a vibration control measure was considered, and after simulation, the level was reduced by one rank and improved to a rating of "not very anxious or not very uncomfortable" (Figure-1).
Figure 1: Preliminary simulation results
One of the requirements for a TMD to be effective in the area of environmental vibration caused by wind is that the weight must operate properly (without losing out to friction) even with relatively small shaking of a few gal. For this project, a pendulum-type horizontal TMD with a mass of 10 tons, which is less affected by frictional force, was adopted and installed on the rooftop floor. (Table-2) (Figure-2)
Table 2. equipment summary
Figure 2. horizontal TMD (left: exterior view, right: installation)
result
As a result of the countermeasures, the TMD resulted in a much faster convergence for both X and Y, with a damping ratio of 6.81 TP3T instead of 11 TP3T (Figure-3) (Table-3).
We were able to ensure a level of livability that does not cause anxiety or discomfort without decreasing the area of the building.
Figure 3. free vibration measurement results (left: X-direction, right: Y-direction)
Table 3. additional attenuation due to TMD and assumed additional attenuation
Related Pages
- Wind shakes the building? How to achieve comfortable occupancy?
- AMD vs TMD In-depth Comparison
- Product Information TMD (Tuned Mass Damper)