Design Sterling CLT to the NDS

Sterling (Sterling Structural) manufactures TerraLam cross-laminated timber. In the US it is recognized under ICC-ES ESR-5053, rated to ANSI/APA PRG-320. SPEC Toolbox designs the panels to the NDS, in allowable stress design or LRFD.

The integration covers Sterling TerraLam CLT, at least three planed sawn-lumber laminations glued crosswise and face-bonded with a non-formaldehyde polyurethane structural adhesive.

• Three grades by species: V3+ (No. 2 Southern pine), V4+ (No. 2 SPF-South) and EH-T (No. 2 Eastern hemlock-tamarack).
• Layups TL300S, TL500S and TL700S (three, five and seven plies), 4-1/8 to 9-5/8 in. thick, in panels up to 8 ft wide and 18 ft long.
• Applications in floor, roof, and interior and exterior wall panels.

At a glance, in the US scope the Sterling TerraLam panels support:

• Load-bearing floors, roofs and interior and exterior walls.
• Allowable stress design (ASD) or LRFD.
• Dry service (in-service moisture content below 16 percent).
• Compliance with the Chicago and California building codes, including DSA and OSHPD.

• Three grades across three species. V3+ in Southern pine, V4+ in SPF-South and EH-T in Eastern hemlock-tamarack, each with reference bending, stiffness and shear in the major and minor directions, so the panel can be matched to the demand and the regional supply.
• Designed in ASD or LRFD. The same reference design values serve allowable stress design or, adjusted with the NDS Table 10.3.1 factors, LRFD.
• Non-formaldehyde adhesive. The panels are face-bonded and finger-jointed with a non-formaldehyde one-component polyurethane structural adhesive.
• Broad US code coverage. The panels carry Chicago and California building-code supplements, the latter covering the DSA and OSHPD/HCAI review agencies.

The Sterling TerraLam panels are available across the SPEC Toolbox CLT modules, worked in ASD or LRFD to the NDS:

• CLT floor, CLT wall and CLT shear wall.

and in the connection modules:

• the screw connection module and the panel-to-panel connection details (spline, butt joint and half-lap);
• CLT floor-to-glulam beam, CLT floor-to-floor and CLT wall-to-wall connections.

Panel behaviour is taken from the integrated database with the reference design values of ESR-5053, using the grade specific gravity (Southern pine 0.55, Eastern hemlock-tamarack 0.41, SPF-South 0.36) for fastener design.

Design follows the ANSI/AWC NDS under the IBC and IRC. ICC-ES ESR-5053 publishes ASD reference design values for TerraLam CLT, rated to ANSI/APA PRG-320: effective bending capacity, bending and shear stiffness, and shear, in the major and minor directions, for the V3+, V4+ and EH-T grades. These are adjusted per NDS Table 10.3.1, without the lumber size or flat-use factor, with a creep factor of 2.0 applied to long-term deflection; LRFD strengths are obtained by multiplying by the NDS Table 10.3.1 factors. The laminations are No. 2 Southern pine, SPF-South or Eastern hemlock-tamarack, the basis for connection design per the NDS. The evaluation is for dry service (in-service moisture content below 16 percent); fire resistance is determined by calculation per NDS Chapter 16 or by test to ASTM E119, and shear-wall unit shear follows the AWC SDPWS. The panels also carry Chicago and California (including DSA and OSHPD) building-code supplements.