Bài 4 của loạt bài về kết cấu của Bảo tàng Edo Tokyo
This document from "Steel Construction Engineering" (March 1994) details the structural engineering design of a vibration control system for a large-span building.
• The system uses air springs to reduce vibration acceleration from the structural floor by approximately 75%. [1, 2]
• It incorporates hydraulic dampers to absorb earthquake energy and linear slides to manage horizontal forces. [1, 2]
• A total of 252 units were installed to protect exhibition items from vertical earthquake movements. [1, 3]
Translation
• Figure 7: Analytical Model Diagram. Shows the model for static and vibration analysis, assuming the first-floor slab is fixed and mass is concentrated at the intersections of main streets on each floor.
• 4. Vibration Control Device: The design aim is to protect exhibits from earthquakes in large-span structures. A vertical vibration control layer was incorporated into a double floor at the tip of a 2800 $m^2$ cantilever section.
• Design Policies:
1. The primary natural frequency of the device is set to 1Hz or less, as the building's primary frequency is approximately 2Hz.
2. Include a level adjustment function for human walking and exhibit movement.
3. Transfer horizontal shear force to the floor directly below.
4. The maximum vertical stroke of the device is 18 cm or more.
• Figure 8: Layout of vibration control devices.
• Figure 9: Vibration control device.
• Device Components:
• Air Springs: Transfer floor loads to the structural floor below and reduce transmitted vibration acceleration to about 1/4 (primary natural frequency of about 0.8 Hz).
• Hydraulic Dampers: Absorb earthquake energy and suppress amplification near the resonance frequency of the control device.
• Shear Receiving Materials: Transfer horizontal forces during an earthquake to the structural floor.
• Linear Slides: Installed via hard rubber to allow the air spring to move smoothly vertically even when horizontal force is applied to the control device.
• Automatic Level Adjustment Device: Automatically supplies and exhausts air in the air springs to keep the floor level constant despite load changes from rearranging exhibits or large movements of visitors. It does not perform air supply/exhaust during rapid floor load fluctuations like earthquakes, ensuring the response reduction effect of the air spring is not compromised.
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