Seismic Restraint of Services Lab
Work out the seismic design force on pipes, ducts, cable trays and equipment at any floor, then the brace spacing, the number of transverse and longitudinal braces for a run and the anchor loads. Three methods side by side: ASCE 7 Chapter 13 (used with the Dubai Building Code and across the Gulf), NZS 1170.5 with NZS 4219, and an AS 1170.4 style check.
How to use: pick the method and region, the service and its size, the floor it hangs from and the brace you plan to use. Tap i for help.
1. Inputs
2. Restraint layout
Plan of the run with braces, a 3D view of the brace at the floor and how the shaking grows up the building.
3. Checks
4. Force breakdown
5. Same service on every level
Force and brace spacing up the building.
6. How it works
Why services need restraint
In an earthquake the floors accelerate and anything hung from them swings. Unbraced pipes, ducts and trays break, fall or hit sprinkler heads. NZS 4219 (with NZS 1170.5) in New Zealand, AS 1170.4 Section 8 in Australia and ASCE 7 Chapter 13 (used with the Dubai Building Code and widely in the Gulf) set the design force.
Floor amplification
Higher floors move more. All three methods amplify the ground acceleration with height: up to 3 times at the roof in ASCE 7 (1 + 2z/h) and NZS 1170.5 (CHi). That is why braces get closer together on upper floors.
Part factors
ASCE 7 uses an amplification factor ap and a response modification factor Rp for each component: welded steel pipe tolerates more movement (Rp 12) than plastic or cast iron (Rp 3.5 to 6). NZS 1170.5 uses the part ductility (Cph) and a part risk factor Rp, capped at 3.6 times the weight.
Braces
Transverse braces stop sideways swing, longitudinal braces stop movement along the run. Typical maximum spacings are about 12 m transverse and 24 m longitudinal for pipes, closer if the force is high. Each brace and its anchor must carry the horizontal force, and at 45° the anchor also sees an uplift equal to that force.
Teaching and checking tool. Seismic restraint design is specific engineering work: use the current standard, the project seismic parameters, and certified bracing products with tested capacities. TS 1170.5 will update the NZ part provisions.