Significantly reduces vertical vibrations during concerts.
~Just like a trampoline!? What is a vertical vibration isolation frame?~
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In large-scale multi-purpose facilities and live music venues, the vertical swaying of the audience can cause significant shaking in surrounding buildings. When such vibrations occur, facility operators are required to take measures such as prohibiting events by artists whose performances are expected to involve vertical swaying, or limiting the type of music performed, which poses a major challenge for the concert industry. Therefore, Nikken Sekkei has devised a "vertical swaying vibration isolation frame (Patent No. 7088664)" to reduce the vibrations caused by vertical swaying.
We aim to contribute to urban development by creating facilities where people can enjoy a wide range of entertainment.
The effect of "vertical vibration isolation frame"
The "Vertical Vibration Isolation Frame" reduces vibrations by 80-90% by designing the beams installed beneath the floor of concert venues, such as the audience seating area. For example, a concert with 5,000 attendees can reduce the vibrations transmitted to the ground to the same level as a concert with 500-1,000 attendees. This makes it easier to host music concerts even in multi-purpose facilities primarily intended for uses other than concerts, leading to increased profits for operators.
Why do surrounding buildings shake when people move?
~The cause is resonance~
Vertical vibrations can cause specific buildings hundreds of meters away to shake violently through the ground. The reason why specific buildings shake so violently is due to a phenomenon called "resonance." Resonance is a phenomenon in which vibrations within a building are amplified by tens of times when the period of ground shaking caused by an earthquake or other event matches the natural period (natural frequency) of each building. In buildings with the same natural frequency as the vibrations caused by vertical vibrations, resonance occurs, resulting in shaking so strong that it disrupts people's lives.
Buildings that resonate due to vertical vibrations and buildings that do not resonate
Simulation results of ground vibration propagation during longitudinal vibration in a certain type of ground.
(Horizontal displacement diagram of the ground cross-section)
The mechanism of the "vertical vibration isolation frame"
~Reducing vertical vibrations with "soft, heavy" beams~
Normally, beams supporting the floor are designed to be "hard and light" to ensure performance, but in this structure, beams are deliberately made "soft and heavy" to significantly reduce vertical vibrations. The principle is the same as how vibrations are less transmitted to the floor when you jump on a soft trampoline. However, simply making it soft would make the person jumping vertically feel floaty and nauseous, so weights and vibration damping dampers are added to the beams. This suppresses the magnitude and duration of floor sway, ensuring the performance of the hall.
To achieve the above performance, the beams are made of H-SA700, an ultra-high-strength steel material with about twice the strength of commonly used steel frames, and the weights are made of electric furnace oxidized slag aggregate, which has a higher specific gravity than ordinary sand or aggregate and is cheaper than concrete.
To achieve the above performance, the beams are made of H-SA700, an ultra-high-strength steel material with about twice the strength of commonly used steel frames, and the weights are made of electric furnace oxidized slag aggregate, which has a higher specific gravity than ordinary sand or aggregate and is cheaper than concrete.
Differences between a typical hall and a vertical vibration isolation frame
Vibration reduction effect of vertical vibration isolation frame
Demonstration experiment
To verify the above theory, structural experiments were conducted from November 30 to December 23, 2022, and it was confirmed that a "soft, heavy" beam reduces vibrations caused by vertical loads.
Test specimen
Experimental scene
Vibration reduction effect
Development history and future prospects
It was in the 1990s that problems caused by vertical vibrations began to be recognized in society. At the same time, it became clear that there were no effective countermeasures against vibrations that propagated to surrounding buildings with the technology available at the time, and since then, the perception has persisted that vertical vibrations are difficult to counter. In 2015, we received a strong request from a client who said, "We want to install a hall that can host any kind of live performance. We absolutely need you to come up with a solution for vertical vibrations." We re-examined in detail the problems and principles caused by vertical vibrations and explored various possible countermeasures. In the process, we concluded that the most important thing in solving the vibration problem is how to suppress the vibration as close to the vibration source as possible, and proceeded to develop vibration reduction technology that can be implemented directly beneath the floor of the hall. Subsequently, we collaborated with a university to build the theory behind this technology and proceeded to conduct demonstration experiments.
This technology features a simple structure using a common building element, the beam, and is characterized by its high reliability as a vibration isolation system. Moving forward, we will leverage the knowledge gained from experiments to develop a vertical vibration isolation frame with even greater vibration reduction effectiveness, and propose it for various building applications both domestically and internationally.
* Research related to this technology
1. Research on controlling vertical vibrations occurring in facilities that attract crowds and evaluating discomfort considering the dynamic response of the human body (Abstracts of the Architectural Institute of Japan Annual Meeting, September 2020, Ozawa, Asahi, Fukuwa, Komazawa)
2. Vibration characteristics of a large-mass, low-rigidity vibration-isolating frame to reduce excitation force caused by human movement (Abstracts of the Architectural Institute of Japan Annual Meeting, September 2021, Ozawa, Asahi, Fukuwa)
This technology features a simple structure using a common building element, the beam, and is characterized by its high reliability as a vibration isolation system. Moving forward, we will leverage the knowledge gained from experiments to develop a vertical vibration isolation frame with even greater vibration reduction effectiveness, and propose it for various building applications both domestically and internationally.
* Research related to this technology
1. Research on controlling vertical vibrations occurring in facilities that attract crowds and evaluating discomfort considering the dynamic response of the human body (Abstracts of the Architectural Institute of Japan Annual Meeting, September 2020, Ozawa, Asahi, Fukuwa, Komazawa)
2. Vibration characteristics of a large-mass, low-rigidity vibration-isolating frame to reduce excitation force caused by human movement (Abstracts of the Architectural Institute of Japan Annual Meeting, September 2021, Ozawa, Asahi, Fukuwa)
