ANSI/TPI Allowable Loads

ANSI/TPI 1-1995 and ANSI/TPI 1-2002 are the National Design Standards for Metal Plate Connected Wood Truss Construction. The ANSI/TPI 1-1995/1997 NDS is referenced in the 2000 IBC and the ANSI/TPI 1-2002/2001 NDS is referenced in the 2003 IBC.

These standards state: any connection which includes a tension perpendicular to grain stress shall be designed to resist cross grain tension forces. Although the ANSI/TPI 1-1995 and ANSI/TPI 1-2002 standards do not affect the carrying capacity of hangers, the cross grain tension of the lumber may be limiting. The controlling factors that affect the calculated value of the hangers are wood species, cross-sectional area of the wood (number of plys), and the location of the upper most fastener in the hanger (H_E). Hangers with carrying capacities over 800 pounds may be affected by these standards.

USP developed spreadsheets listing allowable loads for face mount hangers attached to one and two ply girder trusses with bottom chords of Douglas-Fir Larch, Southern Pine, Spruce-Pine-Fir, and Hem Fir wood. Each table is sorted by supported member size and various specialty hangers like hip/jack and 45° skewed hangers, based on the following criteria:

ANSI/TPI 1-1995/1997 NDS Allowable Loads
ANSI/TPI 1-2002/2001 NDS Allowable Loads

Example of ANSI/TPI 1-2002/2001 NDS Allowable Load chart.
For readability purposes only partial chart is shown, click image for full chart.

ANSI/TPI 1-1995/1997 NDS Technical Bulletins & General Notes

Hangers unaffected by ANSI/TPI 1-1995:

Hangers with supporting capacities 800 pounds or less.
All top flange hangers such as the JPS, JDS, and HDO hangers are not affected.
The MSH adjustable strap hanger is not affected when installed in a top-min or top-max application (flanges are formed over the top or back of the chord).
Bolted hangers are not affected when attached to a vertical web.
Connectors attached to a solid sawn lumber header, composite lumber such as LVL, PSL, or LSL, and glulam beams are not affected.
Miscellaneous connectors such as straps, angles, supplemental bearing plates, twist straps, and hurricane/seismic anchors are not affected.

ANSI/TPI 1-2002/2001 NDS Technical Bulletins & General Notes

NOTE: The ANSI/TPI 1-2002/2001 NDS calculations are based upon the 2001 NDS where shear parallel to grain (Fv) values are equal to 180 psi for Douglas Fir-Larch, 175 psi for Southern Pine, 135 psi for Spruce-Pine-Fir, and 150 psi for Hem Fir. Values shown may differ from the 2004 USP Full Line Catalog or existing code evaluation report values as they are based on 2001 NDS compared to 1997 NDS nail value calculations.

Hangers unaffected by ANSI/TPI 1-2002:

Hangers with supporting capacities 800 pounds or less.
All top flange hangers such as the JPS, JDS, and HDO hangers are not affected.
The MSH adjustable strap hanger is not affected when installed in a top-min or top-max application (flanges are formed over the top or back of the chord).
Bolted hangers are not affected when attached to a vertical web.
Connectors attached to a solid sawn lumber header, composite lumber such as LVL, PSL, or LSL, and glulam beams are not affected.
Miscellaneous connectors such as straps, angles, supplemental bearing plates, twist straps, and hurricane/seismic anchors are not affected.
Any hanger where (H_E) is at least 85% of supporting member depth.
ANSI/TPI 1-2002 also contains plating methods for satisfying this requirement.

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