THE EARTHQUAKE MINUTE
Selecting the appropriate earthquake straps for hospitals is essential to ensure the safety of the building's occupants and the protection of critical equipment and infrastructure. The specific requirements may vary depending on the hospital’s location, local building codes, and structural characteristics. It is essential to consult with a professional structural engineer or seismic expert to assist in designing a seismic restraint system tailored to the hospital's unique needs.
However, here are some general considerations and types of earthquake straps commonly used for securing nonstructural components in hospitals:
1. Flexible Connectors:
Flexible earthquake straps, used in conjunction with engineered and rigid earthquake brackets, allow for movement during an earthquake without causing damage to the connected units. The seismic straps in these systems act like shock absorbers in shake table testing, allowing for the dynamic and often opposite motion of walls and floor common in earthquakes. This method of fastening is crucial for securing most hospital furniture and equipment.
2. Mechanical Connections:
These are typically metal straps or brackets that firmly attach equipment, medical devices, and fixtures to walls, floors, or ceilings. Remember, the vulnerable aspect of these systems is often the point of attachment to the equipment not where the system attaches to the structure. Attaching these connectors to units often requires drilling into them, which can be problematic: damaging items and voiding warranties.
It is vital that the method of attachment to the unit is well thought out and engineered. Shake table testing has shown potentially devastating performance at these connection points, with tech screws and similar mechanical attachments pulling out of the unit in simulated shaking. For this reason, state-of-the-art high-strain rate adhesive-based fasteners (which make use of adhesive tape) are replacing mechanical connections more and more.
3. Seismic Isolators:
In some cases, seismic isolators may be used to separate certain parts of the hospital from the building's main structure. These isolators absorb and dissipate seismic energy, reducing the transmission of shaking to critical components.
4. Vital Considerations:
When choosing the correct earthquake straps to use in a hospital, it is essential to carefully consider the type of fastening system that will be used. It is best to select seismic fasteners that have been thoroughly engineered and tested, preferably by an independent agency such as the International Code Council (ICC). Also, remember that not all adhesive tape is alike, as there are many options. You will want to use only adhesives that demonstrate exceptional performance under high strain rates, or the sharp and sudden pulling common to earthquakes. They should also have sufficient aging, humidity, temperature, and UV exposure limits common to the space where they are being used and bond well to the necessary substrates. Ensure that the earthquake straps and fasteners do not promote mold growth and that the fasteners themselves are multi-directional, meaning that they cannot be removed by pulling either up or in a lateral direction. When it comes to earthquake brackets, make sure that these are sufficiently manufactured with a minimum of thirteen gage steel or, in some cases, like clean rooms and kitchens, adequate 314 stainless steel.
5. Nonstructural Components Evaluation:
Apart from using the right straps and restraints, it is also essential to assess the vulnerability of various nonstructural components in the hospital and then prioritize the fastening of these items. This evaluation helps focus on critical elements that require special attention. In the state of California, for example, the criticality level of any piece of equipment is determined by the hospital itself, not by any regulatory agency. Items deemed essential by the facility are subject to different regulations pertaining to fastening than other, non-critical items.
6. Compliance with Building Codes:
Always ensure that any seismic restraint system used in the hospital meets or exceeds the seismic design requirements specified in the local building codes and regulations. Remember that most building codes are not intended to provide business continuity. They are there to save lives, not keep your facility open.
Given the crucial nature of hospitals and the potential risks during an earthquake, it is vital to involve experienced engineers who specialize in seismic design to ensure the proper selection and installation of earthquake straps and restraints. These professionals will consider the hospital's specific layout, the equipment used, and the local seismic hazards to create a comprehensive and effective seismic restraint plan.