Seismic Restraint Design
An earthquake is an unpredictable natural disaster. One cannot prevent it but can prepare for it. In many cases, the building itself is well protected by means of proper structural seismic design. But the non-structural components of the building, including but not limited to, MEP (mechanical, electrical, plumbing) and HVAC (heating, ventilation, air-conditioning) systems are as important as the building’s structure itself. And here comes Acrefine’s expertise. We have decades of experience in this field, and we are ready to help you with your seismic restraint design needs.
Seismic restraint design of non-structural components is primarily concerned with two main aspects: First; limiting movement of components to predefined limits, and second; transferring seismic forces safely to the main structure of the building. Let’s take a closer look to these.
Limiting Movement of Components | Restraining
The fundamental nature of the earthquakes causes large movements which effects buildings. Based on the characteristics of the seismic event, each structure has its own unique response. In simple terms, this can be explained the way high rise building would respond compared to couple of storey high construction. The roof of the skyscraper will have the largest movements reaching couple of meters in each direction. Any mechanical equipment installed on the roof like an AHU (Air Handling Units), chiller or cooling tower must be properly attached to the structure to prevent displacement which may cause catastrophic damage and loss of human life. Hence their movements must be limited. This can be achieved by allowing no displacement at all or max of quarter inch at restraint point.
Transferring Seismic Forces | Anchorage
Earthquakes generate seismic forces that result in high G levels and non-structural components at the minimum should be able to withstand these loads without disintegration or catastrophic failure. As seismic forces can act in any direction with horizontal and vertical components, the worst case is considered to choose the correct restraint type and anchors. Seismic force is applied at the centre of gravity, which results in tension and shear loads at restraint and anchor points. Based on these loads, restraint and anchors are selected that can safely transfer the forces to the building structure.
Expected Outcome from Seismic Restraint Design
☺︎ Component restrained and kept in place ➡ YES
☺︎ Loads transferred to structural elements ➡ YES
☹︎ Integrity of the equipment ➡ NO *
☹︎ Functionality of the equipment ➡ NO *
* For the last two, please refer to Seismic Analysis of Equipment section.
Acrefine’s Seismic Restraint Design Services
Seismic protection of buildings is unique to each project which is influenced by the location, building size and type. Hence each project, regardless of its size, requires its own seismic restraint design. Acrefine here can help you with followings and much more:
✔ Overturning Calculations for Floor Mounted Equipment
✔ Sway Bracing Calculations for Suspended Equipment and Services
✔ Eliminating The Need for Sway Bracing (based on code ✪)
✔ Detailed Drawings for Equipment Installation
✔ Layout and Typical Detailed Drawings for Sway Bracing
These calculations are based on well-established international codes and standards. In vast majority of projects, we follow American standards such as IBC and ASCE. Having said that, Eurocode 8 and many local codes are within our capabilities of seismic restraint design.
✪ Eliminating The Need for Sway Bracing
In the case of trapeze installations where steel sections (rather than threaded rods) are used, additional sway bracing may not be necessary. Calculations are then performed to check if these steel sections can withstand the seismic forces and transfer them to the building structure. In some cases, single runs that are supported by short threaded rods could withstand the seismic forces and do not require any bracing. Acrefine can help you to determine whether sway bracing is needed in your project or not. In other words, we can help you save your money and time.
Contact us today to get a complete engineering solution for your Seismic Restraint Design needs.