Seismic bracing design for building services, suspended equipment, suspended ceilings and tall floor-standing equipment, from sprinkler piping to electrical panels and data cabinets. Calculations, layout drawings and installation details to the applicable code.
Four scopes
Most projects need more than one, and we design them as one package. The principle does not change from one to the other: seismic restraint is a load path, not hardware. A brace is only as good as the route its force takes into the structure.
Non-structural components need seismic protection of their own, separate from the structural design of the building. Every bracing design we produce works to two objectives:
Controlled movement plus a clear load path is what separates seismic restraint from hardware that is simply bolted on and hoped for the best.
Not every component needs bracing. Services on short hangers, smaller pipe and duct sizes, and some trapeze-mounted items often fall within the exemptions of the applicable code. We check this before we design anything, so you do not pay for hardware, drawings and installation labour your project does not need.
Under seismic load a braced run or unit pulls on some hanger rods and pushes on others. A rod in compression can buckle, so we check the critical rods and specify rod stiffeners where the length and load require them.
Where the geometry allows it, cable bracing is often the more efficient choice: cables work in tension only and restrain movement without the stiffness, and the cost, of rigid braces. Rigid braces carry compression too, so they must be checked for buckling, which adds calculation, hardware and installation work. Cable bracing is our standard; where tight geometry or a short run calls for rigid bracing, we design that instead.
Sprinkler and standpipe piping carries its own seismic bracing requirements under NFPA 13. We handle that scope inside the same design package, not as a separate job. For fire protection work beyond bracing, see our fire safety engineering service.
Equipment hung from the slab — fan coil units, air handling units, fans, tanks — behaves differently from a pipe run. Its mass is concentrated, so the seismic force is concentrated too, and it has to be restrained in every horizontal direction, not only across a run.
Equipment on spring hangers is resiliently mounted yet seismically restrained. The bracing must not short-circuit the isolation. Cable restraints are installed with a small, controlled slack, set to the design detail: in normal operation the unit floats on its springs, and in an earthquake the cables take up the movement before it becomes damaging.
A suspended ceiling carries more than its tiles. Light fittings, diffusers and grilles sit in the grid, and services pass through it. In an earthquake an unbraced grid swings as one mass, pounds against the walls, and drops tiles and fittings onto the escape routes below.
The grid is braced at intervals with splay wires in four directions, and a compression post at each bracing point stops the grid lifting as the wires pull. ASCE 7 refers suspended ceilings to ASTM E580; we apply it, or the equivalent rule of the code your project follows.
At the perimeter the grid is fixed on two adjacent sides and left free, with clearance, on the other two, so it can move without tearing apart. Light fittings and diffusers get their own support, and sprinkler heads pass through the ceiling with enough clearance that the moving grid cannot shear them off.
Electrical panels, switchgear, data cabinets and vertical tanks stand on the floor, but their height works against them: the taller and narrower the unit, the larger the overturning moment its base anchors must take. Beyond a point, base anchorage alone becomes impractical, and on a raised floor or a thin slab it may not be possible at all. The top of the unit has to be braced.
We brace the unit to the wall or the slab above, and design the brace and the base anchorage to share the load. The brace is only as good as what it lands on: a lightweight partition often cannot take the force, so we check the structure at both ends.
Rows of panels or cabinets are braced as a line-up, tied together and to the structure, rather than unit by unit. Where a unit can be held by its base anchorage alone, the job is an overturning calculation: see Seismic Calculations for Equipment. For data halls, see Data Centre Safety.
Drawings, equipment schedule and project location in; what needs bracing, and what is exempt, out.
Seismic forces, brace spacing, connection and anchor checks to the applicable code.
Restraint locations across the full services and equipment scope.
Brace, hanger and anchor details for the site team.
Inspection of the installed bracing against the design. Part of the package when the project needs it; the design stands on its own without it.
Bracing keeps a component in place and carries the seismic loads it generates into the structure. It does not, by itself, prove the component’s internal integrity, or that it still works after the event. Those questions are answered by analysis or testing, for suspended and floor-mounted equipment alike.
Related serviceSeismic Calculations for Equipment Floor-mounted equipment anchored at its base: overturning calculations, equipment seismic analysis and shake table test consultancy.Sample report
Sample report · ACR-SAMPLE-SB-01
Cable bracing layout, brace spacing, rod stiffener check and anchorage for a chilled water main, under ASCE/SEI 7-22.
Summary edition · 6 pages · PDF 1.2 MB
Every page carries a QR code you can check at acrefine.com/verify. The project and figures are fictional; see our Terms of Use. Fuller editions are available on request.
Questions
No. Depending on the code and the seismic category of the building, short hangers and smaller sizes are often exempt. Checking the exemptions is the first step of every design we do.
Cable bracing is our standard: lighter and quicker to install. Where tight geometry, a short run or the available structure calls for it, we design rigid bracing instead.
Yes, on request. Site verification checks the installed bracing against the design and can be part of the package. The design stands on its own without it. It does not replace the inspections your project’s specification requires.
Yes. Every calculation is signed by the Acrefine engineer responsible for it. Where your jurisdiction requires the signature of a locally registered engineer, the report is prepared for their review; on US-code projects that need a PE stamp, we arrange it through our licensed US partner.
Standard bracing components are available through our online store Fixing Smith. Project-specific and heavy-duty items come directly from us.
Yes, where the manufacturer publishes certified ratings for its bracing. Expect a significantly higher fee, though: the ratings and installation details of our own products are already built into our designs, while another manufacturer’s have to be obtained, checked and worked into the design from scratch for your project.
Often, yes. Send us what you have and where the building is; we will tell you whether it falls within our scope.
Our products
Seismic RestraintThe braces and hangers our designs specify — standard ranges through our online store Fixing Smith, project-specific units directly from us.
Describe the components and where the building is.
We will tell you what needs bracing — and what does not.
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