Seismic Analysis of Equipment
There are three possible ways that are widely accepted in the industry for MEP / HVAC equipment to be used where seismic protection is required. These are:
- Overturning Calculations
- Equipment Seismic Analysis
- Shake Table Testing
Overturning Calculations
As per international and local building codes and standards, the minimum requirement is to perform seismic calculations to make sure non-structural components are properly installed. The starting assumption is that the equipment is built sturdily and would not collapse under seismic forces. Hence the primary concern is to secure the equipment to the structure and minimize movement during a seismic event that may cause damage. This is also widely referred to as anchorage calculation since the aim is to transfer the seismic loads trough fixing components (such as anchors and bolts) to the load bearing structural element like a slab floor or ceiling.
First the magnitude of the seismic force is determined and then applied in the worst direction possible. It is then assumed that this force acts on the center of gravity of the equipment causing overturning that generates moment forces at the restraint points. Based on the restraint type and their ratings, these forces create tension and shear forces at the anchors. Selecting the correct type and number of restraints and anchors to transfer the seismic forces without failure completes the restraint design. Depending on each project requirement our engineers also produce detailed installation drawings that promote correct installation.
Analysis
FEA (Finite Element Analysis) or other analysis methods can be used to investigate the structural integrity of the equipment to make sure it will not disintegrate under the seismic forces. The primary concern is to satisfy the mechanical strength criteria with the aim to prove that components or sections of the equipment will not dismantle or fail, and the equipment will remain as single piece.
To perform an equipment seismic analysis, having a 3D model of the equipment is the starting point. Without it, no analysis can be performed. The 3D model of the equipment is used as the input data, along with project specific seismic parameters, which are essential to determine the seismic forces acting on the equipment. Special analysis software is used to perform the analysis, once all necessary input data are in place. Acrefine can help you qualify your equipment via analysis method. All you have to do is to supply the 3D model of your equipment, along with your job specification.
It is important to point out that the aim of equipment seismic analysis is not to prove that the equipment will be in fully functional state after the seismic event. For this aim, shake table testing is the only method.
Testing
In some projects, the equipment is expected to be fully functional after a seismic event. These are typically mission-critical facilities like nuclear plants, datacenters, and military bases. As such, qualifying equipment based on calculations and analysis is not adequate or acceptable and practical means are employed like a full-scale shake table testing. These tests can be single axis or multi-axes and will simulate various past earthquakes or acceleration criteria set by building codes or project specifications.
There are only a handful of testing facilities around the world, where you can have your equipment tested. The challenges are the high costs and extremely long waiting times. Having said that, if you decide to have your equipment tested, Acrefine here can help you. We offer consultancy services for shake table testing. Being a member of SECED (The UK’s Society for Earthquake and Civil Engineering Dynamics) and SPONSE (The International Association for the Seismic Performance Of Non-Structural Elements) we have close relations with testing facilities in Europe.
Contact us to find out what method suits you best, and to get a quotation.