Seismic Rated Access Platform
November 9, 2020
Unistrut Midwest specializes in providing walkways and access platform solutions for almost any application. We get many requests for unique platform solutions and the Unistrut system can be customized to meet the project requirements. One common design request Unistrut gets would be for platforms that are rated for seismic zones.
Seismic Zones create unique challenges in the design of platforms or walkways because you must brace the system in multiple directions. A typical Unistrut Access platform would be designed to handle a 40-50psf dead load and 200 pound horizontal force at the handrails. The standard systems would use some lateral bracing for rigidity but the amount of bracing is minimal. The non seismic platforms can get by with anchor points to a mechanical unit or post bases to a concrete slab.
In a seismic zone, all of the standard platform design criteria must be included in the design. However you must also factor in lateral forces in the event of an earthquake. In order to make a Unistrut Access Platform rated for seismic applications, we must add longitudinal and transverse bracing at every support. The bracing in both directions would prevent any movement of the support in the event of an earthquake. For our seismic bracing Unistrut Midwest used P1000 channel with P1546 and P3810 fittings. The seismic braces were installed in alternating directions and on opposite sides of the walkway. This allowed us to use the minimum amount of material while achieving the required lateral support
Seismic bracing is a relatively simple solution using the Unistrut Seismic design guide found here: Unistrut Seismic Bracing. Unistrut is the global leader in seismic bracing. Unistrut has recently acquired an OPM pre-approval from OSHPD which is the preeminent governing body on seismic standards. The OPM for the Unistrut seismic bracing products gives you the confidence you are using a fully engineered, designed, and tested solution for your seismic application.