Alerting when the vibration standard is exceeded: how does it work?
Vibration monitoring is important to determine whether the vibration levels released by construction activities or an infrastructure project remain within acceptable values. These values relate to either the risk of damage to buildings or the potential nuisance for people living or working in buildings.
It is important that you are quickly informed of any exceedances of the vibration standard. This can be quite a challenge, especially since modern equipment makes it easy to measure from a remote location. You may not be physically present at the construction site. Fortunately, the brains responsible for the technology have found a solution: automatic alarm notifications whenever the vibration standard has been exceeded. In this blog article you can read how this works and what the possibilities are.
Vibration standards: how to determine them?
There are several factors that combine to determine the vibration standard for a given project. We briefly list them here for you.
The condition and function of a building
The condition and function of a building are important factors in establishing a maximum and/or acceptable vibration standard. It is obvious that an aged monumental building that has already been scarred by the ravages of time, can handle a lesser vibration load than a recently built state-of-the-art concrete building. Determining the condition and state of the building is needed in order to choose which vibration standard is acceptable.
The particular use of a building also plays an important factor. What are the people who are occupying that building doing throughout the day? For example, it is extremely important, and even life saving, that a surgeon operates in a room without the disturbance of vibrations. In contrast, a factory worker who works in a noisy environment, and feels higher level vibrations will most likely still be able to perform their job well. The use of a particular building is important to determine when establishing an acceptable vibration standard.
The time of day is also an important factor. It can be assumed that the more irritated a person is, the more sensitive they are to experiencing nuisance. When you go to bed tired but satisfied after a long day of work, you are more sensitive to vibrations than when you are busy during the day doing some simple house chores. A lying position also increases our sensitivity to vibrations.
Duration and intensity of vibrations
The duration and intensity of vibration also help determine the vibration standard. There are a number of values that are important in this regard.
- The top value (expressed with the symbol Vtop) of the vibration velocity and the corresponding dominant frequency. This data will show you the maximum vibration load created during the measurement.
- The duration of the vibration is also a standardizing factor. If a construction project lasts only a few days, the vibration standard is less stringent than if a pile driver is in the same spot for weeks.
Peaks and Averages
The nature of the vibrations also plays a role. Is there an average and consistent level of vibrations or are there sharp and sudden spikes in vibration intensity?
Limit- or target values?
The type of value you use as a starting point for a measurement also helps determine the vibration standard. Do you measure limit- or target values? A limit value is a hard upper limit usually expressed as a probability in percent, while the target value is a standard that takes into account desirable and acceptable averages.
To translate this to vibration monitoring: when a limit value is exceeded, the risk of damage to buildings becomes unacceptably high, whereas a target value indicates a vibration level that is not bothersome to most building users in a given situation. The target value thus averages, as it were, the varying tolerance levels of people.
Alarms when vibration standards are exceeded
To reiterate, you must always perform a measurement based on certain guidelines that have been established using the variables mentioned above. Does a vibration continuously exceed the norm? Then it is important to correct it in time or to stop or slow down the work. With an alarm notification you know that you’ll never be too late to take action.
You can receive such an alarm in several ways. For example, with Omnidots you can choose to be alerted by email, SMS or notification on the Honeycomb web platform. In Honeycomb, a user can set three alarms for a measurement point. For each alarm, you can choose a percentage relative to the guideline.
For example, does the chosen guideline dictate that vibrations from 2mm/s onwards are overruns? If you then have your alarm set to 80 percent, you will receive a signal when a vibration of 1.6mm/s or higher occurs. In addition, you can give each alarm a name and set a custom text message.
Certain measurement systems also allow you to set alarm frequencies in the form of a minimum number of exceedances. A single outlier over a few days, for example, does not automatically mean that you have to shut down a project, especially in the case of an SBR-B measurement. In such a case, for example, do you set a 3? Then you only get a warning if a certain vibration level is measured 3 times within a minute.
You can also set a minimum interval time between emails and text messages (rate limiting) to prevent alerts from coming too quickly and incessantly. In addition, you can determine which people should be notified when a vibration standard is exceeded. These contacts are usually added per measurement project. Is an employee on vacation or have a day off per week as standard? Then you can simply set up the alarm so that he or she does not receive any notifications on those days absent. Has a project ended? Then you can archive it and it disappears from the list of active projects.
Want to know more?
Setting alarms is the best way to consistently stay within a project's vibration standards. You get quick notifications of exceedances, which also allows you to respond more appropriately. Moreover, with an advanced measurement solution like Omnidots, you have a lot of flexibility in choosing the way you want to receive alerts. Curious about the possibilities? Feel free to take a look at our website, read our FAQ section or contact us for more information.