New Penn State approach steadies floors too flexible for comfort

September 21, 2001

University Park, Pa. --- A Penn State architectural engineer has developed a less disruptive, more cost-effective, active control approach to steadying floors that move excessively and annoy or frighten people who walk, work, exercise or dance on them.

Dr. Linda M. Hanagan, assistant professor of architectural engineering, says, "People don't think floors should move, and when they do, this motion can be perceived as annoying or even dangerous. This perception of danger can persist, even though no danger is present."

Stiffening or thickening the floors in an existing building to decrease excessive motion is costly and can take months to complete, disrupting the building's occupants, she adds. However, Hanagan's new approach can be more effective than other structural retrofits and often takes less than a week to fix the problem.

Hanagan's approach, for which Penn State recently filed a provisional patent application, uses active control systems installed on the floor or in the ceiling cavity below it to damp the vibrations.

For example, if people are doing the bunny hop, the hop, hop, hop motion can cause a long-span, steel floor to begin to vibrate in response to the up-and-down motion of the dancers. Each time the dancers hop, the regular "beat" can cause the floor's up and down motion to increase. Hanagan says, "This happens because a component of the 'beat' is in resonance with the natural frequency of the floor."

The researcher's solution is to use strategically placed "smart" counterweights that sense the magnitude of the floor's motion and move to apply opposing forces to damp or diminish the vibrations. The active control system detects when the floor is moving up and down and when to react in the opposite direction to counter the movement.

The Penn State architectural engineer notes that her active floor vibration control system is similar in concept to the tuned mass damper (TMD) approach that is sometimes used to correct floor motion. Both Hanagan's approach and TMD rely on a moving mass to dissipate the energy in the floor system. The advantage of the active system, which uses floor velocity measurements to generate the amount of force needed to damp the floor motion, is that it requires less moving mass to get the same degree of control as a TMD system. One study showed that a TMD system would have to weigh 30 times more than the active control system.

"When TMDs have been ruled out as a repair option because the existing structure can't support the additional weight, the active system could be the only viable option," Hanagan adds.

The active system is cost effective too. "As recently as a few years ago, 20 pounds of force cost about $30,000 to generate. Today, thanks to the improved capabilities of commercially available linear motors, we can generate 500 pounds for about $50,000," she notes. The Penn State researcher is currently working on a non-exclusive basis with a commercial partner to apply her approach. She also measures and assesses floors on a consulting basis. In addition, she conducts research to provide design engineers with better tools to predict vibration behavior and prevent vibration problems before a building is constructed.
Hanagan's early work on active control of floor vibration was supported in part by the National Science Foundation. The active control approach has been described in publications including Experimental Implementation of Active Control to Reduce Annoying Floor Vibrations in the Engineering Journal, fourth quarter issue, 1998. Other publications are noted on Hanagan's website at

Penn State

Related Active Control Approach Articles from Brightsurf:

Differences between discs of active and non-active galaxies detected for the first time
A study led by researchers at the Instituto de Astrofísica de Canarias (IAC), making comparison between the discs of several pairs of spiral galaxies, active and non-active, concludes that in the discs of the former the rotational motion of the stars is of greater importance.

Scientists discover volcanoes on Venus are still active
A new study identified 37 recently active volcanic structures on Venus.

Don't Let social isolation keep you from being active
Researchers from the University of Sao Paulo in Brazil recently reported on the dangers of physical inactivity for older adults during the COVID-19 pandemic.

Sun is less active than similar stars
By cosmic standards the sun is extraordinarily monotonous. This is the result of a study presented by researchers from the Max Planck Institute for Solar System Research in the upcoming issue of Science.

New active ingredient against allergic asthma
Our immune system protects us against pathogens. However, an excessive immune reaction can trigger allergies or chronic asthma.

Active droplets
Using a mixture of oil droplets and hydrogel, medical active agents can be not only precisely dosed, but also continuously administered over periods of up to several days.

The regulators active during iron deficiency
Iron deficiency is a critical situation for plants, which respond using specific genetic programmes.

Hints of a volcanically active exomoon
A rocky extrasolar moon (exomoon) with bubbling lava may orbit a planet 550 light-years away from us.

Artificial DNA can control release of active ingredients from drugs
A drug with three active ingredients that are released in sequence at specific times: Thanks to the work of a team at the Technical University of Munich (TUM), what was once a pharmacologist's dream is now much closer to reality.

Keeping active or becoming more active in middle and older age linked to longer life
Keeping physically active or becoming more active during middle and older age is associated with a lower risk of death, regardless of past activity levels or existing health conditions, suggests a large UK study published by The BMJ today.

Read More: Active Control Approach News and Active Control Approach Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to