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
a.
Design
and supply a complete light gauge steel roof system stamped by a registered
engineer to include all of the following components:
1.)
Light gauge steel trusses for gravity and
lateral loads with truss sizes, gauges and connections at truss joints.
2.)
Design
and stamp truss to truss connections and truss to bearing connections for
gravity, lateral and uplift loads.
3.)
Design
and stamp the top cord, bottom cord and web permanent bracing locations.
4.)
Design
and stamp the roof deck structural support at eave edge, valley, hip and ridge
transition planes to support corrugated steel or plywood decking.
5.)
Design
the roof deck shear transfer framing required to transfer the roof deck shear
to the building structure. The Engineer-Of-Record or Architect is responsible
to determine the roof diaphragm, to determine the location and magnitude of the
roof shear transfer and to determine location within the building structure
through which this shear will pass.
6.)
Provide
stamped calculations and shop drawings for project submittal requirements.
b.
Truss
manufacturer is to inspect the roof and/or floor trusses after the installation
is complete and issue a written report indicating whether the trusses were
installed per Part 3 ‘Execution’.
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 the truss ability to meet local code and design
requirements. Specifically include the
engineering and design for all of the following:
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 system.
Fabrication and installation by:
Superior Truss & Panel, Inc.
2204 West 159th Street
Contact: Mike Goncher or Bryce
Welty
2.
Request
for substitutions will be considered in accordance with provisions of Section
01600. The Architect or Engineer of Record must approve all permitted equals in
writing. All applications for substitutions must include samples and technical
data.
2.02 COMPONENTS
A.
System
components: MiTek Industries, Inc.
ULTRA-SPANâ light gauge steel roof
trusses and floor 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 package.
2.03 MATERIALS
A.
Materials:
1.
All
component gauges: Fabricate components
of structural quality steel sheet
per ASTM A653/A653M-95 with a minimum yield strength
of 45,000 psi.
2.
Bracing,
bridging and blocking members:
Fabricate components of commercial
quality steel sheet per ASTM A653/A653M-95 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,
0.0350 inch (0.91 mm).
2.
Design
Uncoated-Steel Thickness: 18 gauge,
0.0460 inch (1.20 mm).
3.
Design
Uncoated-Steel Thickness: 16 gauge,
0.0570 inch (1.52 mm).
4.
Design
Uncoated-Steel Thickness: 14 gauge,
0.0730 inch (1.90 mm).
C.
Finish: Provide components with protective zinc
coating complying with ASTM
A653/A653M-95, 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.
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. Use of a crane or lull
with a spreader bar is recommended for trusses longer than 30 foot. 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 installations until unsatisfactory
conditions have been corrected. Verify that the bearing elevations are correct
before trusses are installed.
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 Subcontractor. The use of a crane or lull with
a spreader bar is recommended for trusses over 30 foot.
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” October, 1999.
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 and the anchor must be attached to the correct side
of the truss as shown in the truss drawings and attachment details.
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 manufacturer.
2.
Fasten
cold-formed steel roof framing by mechanical fasteners only per truss
manufacturer’s recommendation. 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 truss 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
temporary 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
1/4 inch in 10 feet (1:480) and as follows:
a.
Space
individual trusses no more than plus or minus 1/4 inch 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)
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
bridging at each end of trusses and at intervals indicated. Fasten bridging at each truss intersection
as follows:
1.
Bridging: Cold-rolled steel channel or cold-formed
steel section, fastened to truss bottom chord.
2.
Bridging: Flat, steel-sheet straps of width and
thickness indicated, fastened to truss bottom chord flange.
3.
Bridging: Cold-formed steel section strongback (6”
minimum), fastened to truss web or other means.
F.
Secure
trusses to load-bearing interior walls to prevent lateral movement of bottom
flange.
G.
Install
miscellaneous truss framing and connections, including closure pieces,
clip
angles, continuous angles, hold-down angles, anchors, and fasteners, to provide
a complete
and
stable truss-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.
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
construction continuous bridging, bracing, cross bracing and diagonal bracing
per Light Gauge Steel Engineers Association (LGSEA) publication “Field
Installation Guide For Cold-Formed Steel Roof Trusses” October 1999.
H.
Attach
trusses to trusses per truss manufacturer’s recommendation.
I.
Attach
trusses to bearing per truss manufacturer’s recommendation.
J.
Attach
permanent truss lateral and diagonal bracing per manufacturer’s recommendation.
K.
Attach
roof deck or sheathing structural support per truss manufacturer’s
recommendation.
L.
Attach
roof deck shear transfer framing per truss manufacturer’s recommendation.
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.
3.06
ISSUE
FINAL INSPECTION REPORT
A.
Truss
manufacturer is to inspect the roof and/or floor trusses after the installation
is complete and issue a written report indicating whether the trusses were
installed per Part 3 ‘Execution’.