How Vibrations Affect Structures and People

Defining Vibrations

Vibrations are motions that can affect structures and people. There are different types of vibrations. Periodic vibrations are defined as oscillatory motion with a repetitive motion. Random vibrations are instantaneous and occur at different times that are not predictable. Vibrations can occur anywhere from a multitude of sources. Construction is a common example of activities that can result in vibration frequencies. The use of generators, jackhammers, and drills can cause waves of vibrations. Transportation services, specifically train activity, can induce higher vibration levels. High vibration levels can impact structures and potentially cause damage. To avoid hazards and damage from occurring, vibration monitoring can be an effective way to ensure the safety of people and structures.

How Vibrations Can Affect Structures

In 1940, the Tacoma Narrows bridge in Washington collapsed as a result of vibration. The suspension bridge was designed without thought of how wind can cause high torsional oscillations. The wind reached up to 40 mph when it collapsed. The vibrations that caused the collapse have been heavily studied. When structures are being built, many contractors are now required to have a third party complete construction vibration monitoring to reduce the risk of potential structural damage from their activities to the neighbouring properties. Long term unattended vibration monitoring can also bring awareness of imbalances and misalignments. If vibration monitoring was around during the Tacoma Narrow suspension bridge construction, a warning of impending failure might have been predicted.

Vibrations known as resonance are defined as when a product or person experiences an externally forced vibration. Resonance vibrations can cause damage and harm by forcing and swaying structures. Structures that can experience resonance vibrations include bridges, buildings, trains, and airplanes. The impact of this movement is that it can potentially loosen bolts, cause cracks, or in extreme cases, even result in failure. When the issue is monitored and proactively reviewed, vibration mitigation can be implemented to reduce or potentially prevent the potential impact. For example, car manufacturers can assist in reducing levels of resonance vibrations by using vibration monitoring tools to determine the frequencies of concern so that a targeted vibration mitigation plan can be implemented to extend the life of the equipment.

Construction and Vibration Monitoring

When construction occurs, elevated vibration levels can occur. Noise and vibration monitoring is becoming a necessary tool when it comes to construction sites. Recording the levels of vibration can help determine if there is an issue within the structure that needs to be immediately addressed. Addressing construction vibration levels upfront can help avoid future surprises. Monitoring noise can help protect the workers on site and can potentially reduce nuisance to the surrounding neighbours. Monitoring noise and vibration can result in prioritizing health and safety.