When an unbraced truss chord is assumed to be continuous in the structural analysis, bending moments will exist in all panels.
ANSI/TPI 1-1995 (12) states that the maximum initial deflection allowed in a truss chord is the lesser of L/200 or 2 inches.
Screw each truss chord to the tie plate (Photo 18 inset).
B) through the floor of the loft and into a block positioned between the truss chords. These braces are necessary to add rigidity to the roof.
Type I: steel truss chords keep in elastic stage and the deformation is small; overall bending deformation occurs in diagonal web members, with [[rho].sub.A] [less than or equal to] 0.4 and [[rho].sub.K] < 0.15.
Type II: steel truss chords deform to some extent, diagonal web members buckle locally, it is likely that chord members will enter the plastic stage, but within a limited degree, with 0.4 < [[rho].sub.A] [less than or equal to] 0.65 or 0.15 [less than or equal to] [[rho].sub.K] [less than or equal to] 0.2.
The final result confirms the judgement made during the design, as the faceting of truss chords
and ring beam is visually imperceptible.
The adjacent truss chords
overlap on alternating sections providing zones suitable for splice joints.
To keep the attic cooler, opt for a lighter color roofing material, insist on an externally baffled ridge vent, consider increasing the insulation thickness in the attic or staple a reflective film to the bottom of the top truss chords
Typically, ducts will be placed on the gypsum board or lower truss chords
, and loose-fill insulation will be installed to a particular ceiling assembly R-value.
If the bathroom is situated on the second floor, keep in mind that existing roof truss chords
or ceiling joists may need structural reinforcement.
The contractor, Chesterfield Associates (Westport Island, Maine), and Jan Lewandoski (Greensboro Bend, Vermont), the subcontractor for heavy timber fabrication, chose the option of glulam southern yellow pine timbers for the truss chords
. Heavy southern yellow pine timbers were used for the truss diagonals and lateral bracing.