I have a structure with long support spans and in order to keep the vibration generated by the roof mounted equipment from causing problems, a spring with more than 2 inches of deflection is needed. However, when I put equipment on these springs , it rocks excessively in a breeze or when I push against …
When should I use inertia blocks with the vibration isolators? ANSWER: There are three major reasons for including an inertia mass with the isolation. One is that it lowers the center of gravity of the system. For a tall narrow unit, this could make the installation more stable in a seismic event. Secondly, some pieces …
If the vibrating equipment is located outside on the ground, do I still need to use vibration isolators? ANSWER: Even if the equipment is on grade on a separate slab from the building, vibration transmitting to the building structure is still a concern. Also, the addition of isolators will reduce enough vibration that it is …
Why should I use vibration isolators? ANSWER: All mechanical and electrical equipment generates vibration. Even a small amount of vibration energy traveling through the structure can: Create unacceptable noise levels in commercial buildings, schools, auditoriums, etc. For example, government standards now require quieter environments for school children to enhance learning. Affect sensitive equipment such as …
Should both internal and external vibration isolation be used in a single application? ANSWER: It is possible that the internal springs could resonate with the external springs. This could cause damage to the systems. If the application is near a very vibration sensitive area, the internal isolators should remain locked down; as they are when …
I am thinking of replacing an aging air conditioning system. Should I add seismic restraint devices with the installation? ANSWER: In the event of an earthquake of a magnitude large enough to cause your air conditioning equipment and piping to break loose, you could lose the use of the building and have the risk of …
Is it possible that a building could be uninhabitable after an earthquake, even with no structural damage? ANSWER: The heating and air conditioning system equipment are considered to be non-structural components of the building. If the building has little or no structural damage but the water piping or air conditioning systems have torn loose or …
The seismic design forces have greatly increased with the advent of the current code in my area. In addition, there is a lot more information that I need to have to determine what force is appropriate. Why is this? ANSWER: During the 1989 and 1994 earthquakes that occurred in California, considerable information was gathered that …
What is “special inspection” for anchor bolts? ANSWER: The actual installation of the bolt into the concrete is a critical part of the restraint system. If the bolt is not embedded deeply enough or properly set into the concrete, it could fail in an earthquake. Special Inspection requires an independent authority to watch the installation …
Why do I sometimes need to add oversized mounting plates to restraints attached to concrete ANSWER: The seismic restraint manufacturer has probably designed the steel restraint so that it is stronger than the material it is anchored to. A good example is when there is a requirement to anchor to a thin layer of lightweight …
