PRE-ENGINEERED,
PRE-FABRICATED LIGHT
GAUGE STEEL ROOF
& FLOOR TRUSSES
PART 1: GENERAL
1.01
SUMMARY
A.
Section
includes pre-engineered, pre-fabricated light gauge cold-formed steel framing
elements.
Work includes:
B.
Related
Work
1.02
REFERENCES
A.
Reference
standards:
a.
ASTM
A653/A653M-94 "Sheet Steel, Zinc-Coated (galvanized) or Zinc-Iron
Alloy-Coated (Galvanized) by the Hot-Dip
Process."
b.
ASTM
A780-93a "Repair of Damaged and Uncoated Areas of Hot-Dip
Galvanized Coatings."
a.
AWS
D1.1 "Structural Welding Code - Steel."
b.
AWS
D1.3 "Structural Welding Code - Sheet Steel."
1.03
PERFORMANCE
REQUIREMENTS
A.
AISI
"Specifications". Calculate
structural characteristics of cold-formed steel truss
members according to AISI's "Specification for
the Design of Cold-Formed Steel Structural Members, 1986 (1990)."
B.
Structural
Performance: Design, engineer,
fabricate, and erect cold-formed steel
trusses to withstand specified design loads within
limits and under conditions required.
a.
Floor
Trusses: Vertical deflection less than
or equal to 1/360 of the span
b.
Roof
Trusses: Vertical deflection less than
or equal to 1/240 of the span
damage or overstressing, sheathing failure,
connection failure, undue strain on fasteners and anchors, or other detrimental
effects when subject to a maximum ambient temperature change (range) of 120° F (67°C).
4.
Design the structural support between trusses needed to support the roof
decking / sheathing at
the eave edge, valley, hip and
ridge
5.
Design the shear transfer framing required to collect the roof deck
shear diaphragm and transfer
the shear to the building structure
1.04
SUBMITTALS
A.
Submit
manufacturer's product data and installation instructions for each type of
cold-
formed steel framing and accessory required.
B.
Submit
shop drawings showing member, type, location, spacing, size and gauge of
member, method of attachment to supporting members
and all necessary details. Indicate
supplemental bracing, strapping, splices, bridging, accessories and details
required for proper installation
C.
Submit
detailed floor truss and roof truss layouts.
D.
Submit
truss drawings, sealed and signed by a qualified registered Professional
Engineer, verifying truss' ability to meet local code and design
requirements. Include:
1.05
QUALITY
ASSURANCE
A.
Fabricator
Qualifications: Fabrication shall be
performed by a cold-formed steel
truss fabricator with experience in designing and
fabricating cold-formed steel truss systems equal in material, design, and
extent to the systems required for this Project.
1.
Cold-formed
steel truss system installation shall be performed by an experienced
installer approved by the steel truss system
fabricator.
B.
Welding
Standards: Comply with applicable
provisions of AWS D1.1 "Structural
Welding Code-Steel." And AWS D1.3
"Structural Welding Code-Sheet Steel."
1.
Quality
welding processes and welding operators in accordance with AWS
"Standard Qualification Procedure."
2. Welding
of any nature to these trusses is specifically prohibited unless permission is
received
from the manufacturer.
1.06 DELIVERY, STORAGE AND HANDLING
A.
Deliver
materials in manufacturer's unopened containers or bundles, fully identified by
name brand, type and grade. Exercise
care to avoid damage during unloading, storing and erection.
B.
Store
trusses on blocking pallets, platforms or other supports off the ground and in
an upright position sufficiently braced to avoid
damage from excessive bending.
C.
Protect
trusses and accessories from corrosion, deformation, damage and deterioration
when stored at job site. Keep trusses
free of dirt and other foreign matter.
1.07 PROJECT CONDITIONS
A.
During
construction, adequately distribute all loads applied to trusses so as not to
exceed the carrying capacity of any one joist, truss
or other component
2.01
MANUFACTURERS
1.
MiTek Industries, Inc. "Ultra-Span" truss component
system. Design,
engineering, fabrication and installation by:
Superior Truss & Panel, Inc.
2204 West 159th Street
Contact: Bill Welty
2.
Dale
Industries, Inc. “Versa-Truss” truss component system, Dearborn, MI Phone 313-846-9400 Fax 313-846-7128 Contact
Jeff Klaiman
3.
American
Studco, Inc. “Amkey” truss component system, Phoenix, AZ
Phone 602-272-6606
Fax 602-269-1324 Contact
Michael Meek
2.02 COMPONENTS
A.
System
components: MiTek Industries, Inc.
ULTRA-SPANâ (or equal)
Light gauge steel floor trusses and roof truss
components.
B.
Provide
manufacturer's standard steel truss members, bracing, bridging, blocking,
reinforcements , fasteners and accessories with each
type of steel framing required, as recommended by the manufacturer for the
applications indicated and as needed to
provide a complete light gauge cold-formed steel truss system.
2.03 MATERIALS
A.
Materials:
1.
All
component gauges: Fabricate components
of structural quality steel sheet
per ASTM A653 with a minimum yield strength of
40,000 psi.
2.
Bracing,
bridging and blocking members:
Fabricate components of commercial
quality steel sheet per ASTM A653 with a minimum
yield strength of 33,000 psi.
B.
Ultra-Span
steel truss components: Provide sizes,
shapes and gauges indicated.
1.
Design
Uncoated-Steel Thickness: 20 gauge,
0.0360 inch (0.91 mm).
2.
Design
Uncoated-Steel Thickness: 18 gauge,
0.0470 inch (1.20 mm).
3.
Design
Uncoated-Steel Thickness: 16 gauge, 0.0580
inch (1.52 mm).
4.
Design
Uncoated-Steel Thickness: 14 gauge,
0.0750 inch (1.90 mm).
C.
Finish: Provide components with protective zinc
coating complying with ASTM
A653, minimum G60 coating.
D.
Fastenings:
1.
Manufacturer
recommended self-drilling, self-tapping screws with corrosion-
resistant plated finish. Fasteners shall be of sufficient size and number to ensure the
strength of the connection.
2.
Welding
of any nature to these trusses is specifically prohibited unless permission is
received
from the truss manufacturer.
3.
Other
fasteners as accepted by truss engineer.
2.04 FABRICATION
A.
Factory
fabricate cold-formed steel trusses plumb, square, true to line and with
connections securely fastened, according to
manufacturer's recommendations and the requirements of this Section.
a.
Comply
with AWS requirements and procedures for welding, appearance and
quality of welds, and methods used in correcting
welding work.
b.
Locate
mechanical fasteners and install according to cold-formed steel truss
component manufacturer's instructions with screw
penetrating joined members by not less than 3 exposed screw threads.
B.
Care
shall be taken during handling, delivery and erection. Brace, block or reinforce
truss as necessary to minimize member and connection
stresses.
C.
Fabrication
Tolerances: Fabricate trusses to a
maximum allowable tolerance variation from plumb,
Level, and true to line of 1/8 inch in 10 feet
(1:960) and as follows:
1.
Spacing: Space individual trusses no more than plus or minus 1/8 inch (3mm)
From plan location.
Cumulative error shall not exceed minimum fastening
Requirements of sheathing or other finishing
materials.
2.
Sequences: Fabricate each cold formed steel truss to a
maximum out-of-square
Tolerance of 1/8 inch (3mm).
3.01 EXAMINATION
A.
Examine
structure, substrates and installation conditions. Do not proceed with cold-formed
Steel truss installation until unsatisfactory
conditions have been corrected.
B.
Installation
constitutes acceptance of existing conditions and responsibility for
satisfactory
Performance.
3.02 INSTALLATION, GENERAL
A.
General:
1.
Erection
of trusses, including proper handling, safety precautions, temporary bracing
and other safeguards or procedures are the responsibility of the General
Contractor and the Installation Contractor
2.
Exercise
care and provide erection bracing required to prevent toppling or dominoeing of
trusses during erection as identified in the Light Gauge Steel Engineers
Association (LGSEA) publication “Field Installation Guide For Cold-Formed Steel
Roof Trusses”.
B.
Erect
trusses with plane of truss webs vertical and parallel to each other,
accurately located at design spacing indicated.
C.
Provide
proper lifting equipment suited to sizes and types of trusses required, applied
at lift points recommended by truss fabricator and use spreader bars for larger
span trusses. Exercise care to avoid
damage to truss members during erection and to keep horizontal bending of the
trusses to a minimum.
D.
Provide
framing anchors as indicated or accepted on the engineering design drawing or
erection drawings. Anchor trusses
securely at bearing points.
E.
Install
roof framing and accessories plumb, square, true to line, and with connections
securely fastened, according to manufacturer's recommendations.
1.
DO
NOT cut truss members without prior approval of truss engineer
2.
Fasten
cold-formed steel roof framing by screw fastening as standard with
fabricator. Wire tying or welding of
roof framing is not permitted.
a.
Welding
of any nature to these trusses is strictly prohibited unless specific
permission is received from the manufacturer.
b.
Locate
mechanical fasteners and install according to cold-formed roof framing
manufacturer's instructions with screw penetrating joined members by not less
than 3 exposed screw threads.
c.
Install
roof framing in one-piece lengths, unless splice connections are indicated.
d.
Provide
bracing per Light Gauge Steel Engineers Association (LGSEA) publication “Field
Installation Guide For Cold-Formed Steel Roof Trusses” and leave in place until
trusses are permanently stabilized.
F.
Erection
Tolerances: Install trusses to a
maximum allowable tolerance variation from plumb, level, and true to line of
1/8 inch in 10 feet (1:960) and as follows:
a.
Space
individual trusses no more than plus or minus 1/8 inch (3mm) from plan
location. Cumulative error shall not
exceed minimum fastening requirements of sheathing or other finishing
materials.
3.03 OPEN-WEB FLOOR TRUSS INSTALLATION
A.
Install
perimeter joist tracks or belly band sized to match trusses. Align and securely anchor or fasten track to
supporting structure at corners, end, and spacing indicated or as recommended
by the manufacturer.
B.
Install
trusses bearing on supporting framing, level, straight, and plumb, adjust to
final position, brace, and reinforce.
1.
Install
trusses over supporting framing with a minimum end bearing of 1-1/2 inches
(38mm)
2.
Reinforce
ends of trusses with web stiffeners, end clips, joist hangers, steel clip
angles, steel-stud sections, or as otherwise recommended by manufacturer.
C.
Space
trusses not more than 2 inches (51mm) from abutting walls and not greater than
24 inches on center or less as indicated on the plans.
D.
Frame
openings with built-up joist headers consisting of joist and joist track,
nesting joists, or another combination of connected joists where indicated.
E.
Install
truss reinforcement at interior supports with single, short length of joist
section located directly over interior support, with lapped joists of equal
length to joist reinforcement, or by other method recommended by joist
manufacturer.
F.
Install
bridging at each end of trusses and at intervals indicated. Fasten bridging at each truss intersection
as follows:
1.
Bridging: Cold-rolled steel channel, fastened to
bottom flange of trusses.
2.
Bridging: Flat, steel-sheet straps of width and
thickness indicated, fastened to bottom flange of trusses.
3.
Bridging: Combination of flat, steel-sheet straps of
width and thickness indicated and joist-track solid blocking of width and
thickness indicated. Fasten flat straps
to bottom flange of trusses and secure solid blocking to joist webs
G.
Secure
trusses to load-bearing interior walls to prevent lateral movement of bottom
flange.
H. Install
miscellaneous truss framing and connections, including web stiffeners, closure
pieces, clip angles, continuous angles, hold-down angles, anchors, and
fasteners, to provide a complete and stable joist-framing assembly.
3.04 ROOF TRUSS INSTALLATION
A.
Install,
bridge, and brace trusses according to manufacture's recommendations and
requirements of this Section.
B.
Space
trusses as shown on the plans and approved shop drawings.
C.
Do
not alter, cut, or remove truss members or connections of trusses.
D.
Erect
trusses with plane of truss webs plumb and parallel to each other, align, and
accurately position at spacing indicated.
E.
Erect
trusses without damaging truss members or connections.
F.
Align
truss bottom chords with load-bearing studs or continuously reinforce track to
transfer loads to structure. Anchor
trusses securely at all bearing points.
G.
Install
continuous bridging and permanent truss bracing, cross bracing and diagonal
bracing per Light Gauge Steel Engineers Association (LGSEA) publication “Field
Installation Guide For Cold-Formed Steel Roof Trusses”.
3.05 REPAIRS AND PROTECTION
A.
Galvanizing
Repairs: Prepare and repair damaged
galvanized coatings on fabricated and installed cold-formed steel framing with
galvanizing repair paint according to ASTM A 780 and the manufacturer's
instructions.