How We Determine Allowable Loads
Allowable loads in this catalog are determined by calculations and test criteria established by industry, such as ICC-ES Acceptance Criteria, IAPMO UES Evaluation Criteria and ASTM test standards.
Connectors are typically evaluated in accordance with ICC-ES AC13 — Acceptance Criteria for Joist Hangers and Similar Devices. Evaluation is based on a minimum of three static load tests in wood assemblies. The published allowable load is the lower of the tested ultimate with a safety factor of 3, load at 1⁄8" deflection or the NDS fastener calculation limits.
Holdowns and tension ties are tested in accordance with ICC-ES AC155 — Acceptance Criteria for Hold-Downs (Tie-Downs) Attached to Wood Members. Allowable loads are based on the lower of three static load tests with a safety factor, deflection limits or NDS fastener calculation limits. Static load tests include holdown testing on steel jigs and wood assembly tests.
Cast-in-place concrete products are tested in accordance with ICC-ES AC398 — Cast-in-Place, Cold-Formed Steel Connectors in Concrete for Light-Frame Construction or AC399 — Cast-in-Place Proprietary Bolts in Concrete for Light-Frame Construction. Threaded fasteners are evaluated per AC233 — Alternate Dowel-Type Threaded Fasteners.
Where a test standard is unavailable, testing is conducted per sound engineering principles. Some tests include only portions of a product, such as purlin anchor tests, wherein only the embedded hook is tested, not the nailed or bolted section of the strap, which is calculated. Testing to determine allowable loads in this catalog is not done on connection systems in buildings. Testing is conducted under the supervision of an independent laboratory.
For detailed information regarding how Simpson Strong-Tie tests specific products, contact Simpson Strong-Tie.