GENERAL
This
specification covers the requirements for metal decking as formwork for
cast-in-place concrete floors and roofs.
Metal decking work shall include Contractor's designing detailing,
fabricating, furnishing, installing and inspecting of the Work and shall
conform to the requirements of this specification.
Accessories
for metal decking shall include but not limited to the following:
All fasteners.
Closures, including the following:
- End closures
- Side closures
- Column closures
Reinforcements under metal decking at columns and framed openings,
including miscellaneous structural steel as required for the support of the
metal deck at sleeves and unframed openings shall be cut through the deck prior
to placing of the concrete.
Other accessories as required
CODES AND STANDARDS
The
Contractor shall comply with the requirements of Book II refers to “Codes and
Standards”.
The
codes and standards of the following organizations extracted from Book II
refers to “Codes and Standards” are specifically applicable to the design,
manufacture and testing of the work included in this Specification:
AISI...................... American Iron and
Steel Institute
ANSI..................... American National
Standards Institute
ASTM................... American Society for
Testing and Materials
SDI....................... Steel Deck
Institute. U.S.A
QUALITY ASSURANCE / QUALITY CONTROL (QA/QC)
Contractor shall fully comply with the Project Quality Assurance/Quality
Control Requirements. For submitting Quality Assurance/Quality Control
Procedures and Documentation the Provision of clause “Submittals” of these
specifications shall apply.
DESIGN
DECK
TYPES
Deck type and size shall be designed and
detailed by the Contractor and shall be used only for formwork for
cast-in-place concrete. The deck shall
be suitable for the span and the construction loads.
The
Contractor is allowed to consider the deck as part of reinforcing steel for the
concrete slab.
WELDS, FASTENERS AND OTHER ACCESSORIES
Welds, fasteners and other accessories shall be designed and detailed by
Contractor in accordance with the applicable requirements of AISI Specification
for the Design of Cold-Formed Steel Structural Members and SDI Design Manual
for Composite Decks, Form Decks and Roof Decks, and the requirements of the
Specification for Welding in Steel Construction, unless otherwise indicated on
the Contractor's design drawings.
CONSTRUCTION LOADS
Decks acting as formwork for cast-in-place concrete shall be designed by
the Contractor for the wet weight of concrete plus a minimum 100 kg/m² construction
live loads. Book IIIA Subsection 4.4.3
indicates the responsibility for temporary supports required for any additional
construction loads.
The Contractor shall be fully responsible to any failure of the decking
work because of miss conduct by the Contractor.
SUBMITTALS
After the contract signed, the contractor shall furnish complete and
comprehensive data on material specification regarding all component and
accessories of his propose system for the Owner’s approval.
Test data and
report and the quality control procedures and documentation shall be submitted
to the owner for review.
STORAGE
All
metal decking material, component, fasteners and other accessories shall be
stored dry, off the ground and under cover, in a satisfactory manner.
Contractor
shall responsible for storing these materials in such a manner as to preclude
damages, deterioration, etc. All cost for such protection shall be included in
the contract price.
MATERIAL
SHEET MATERIAL
ASTM A446, Grade A (minimum yield strength 2320 kg per sq. cm) or 320
MPa.
FINISH
Hot-dip galvanized, ASTM A525, Coating Designation G90 (minimum).
FABRICATION AND
INSTALLATION
GENERAL PROVISIONS
Metal decking, including fasteners and all other accessories, shall be
fabricated and installed in accordance with the requirements of this Clause 5,
applicable AISI and SDI Specifications and Standards, and in strict accordance
with manufacturer's printed instructions unless otherwise indicated.
DECK POSITION
For cast-in-place concrete slabs, metal decks shall be installed in
inverted position unless otherwise indicated.
OPENING
No opening through deck shall be cut prior to concrete is placed and
hardened.
Where the span of metal deck for cast-in-place
concrete slabs is parallel to and directly supported by steel beams, provisions
shall be made for full bearing of the rib bottom on steel beams, or the deck
shall be cut and side closures provided. If side closures are provided to form
a rib bottom, the area of the rib profile so formed shall be at least equal to
the area of the deck rib profile.
ALIGNMENT
Metal decking for cast-in-place concrete slabs shall
be installed so that the ribs line up to permit continuity of bottom
reinforcing bars.
CLOSURES
Metal decking formwork for cast-in-place concrete
roofs or floors shall be provided with specific closures, with provisions for
reinforcing bars to pass through, and to prevent leakage of concrete during
placement at the following locations:
Penetrations through metal decking by structural steel
or other members.
Ends or discontinuities of metal decking.
Perimeters of openings and cants in metal decking.
All others as indicated on the Contractor's design
drawings.
VENTILATION
For metal decking formwork for cast-in-place concrete
roofs only, ventilating clips or suitable openings shall be provided for
release of moisture between the concrete and the metal decking.
FIELD CUTTING FOR OPENINGS
Shall be performed by sawing or nipping; the use of
flame cutting, welding electrodes or chiselling will not be permitted.
FASTENING
All metal decks shall be fastened to every supporting
structural steel member. Where the ribs
of the deck are perpendicular to the supporting steel beams and if the rib
spacing of the deck is less than 300 mm, metal deck shall be fastened at the
bottom of every other rib. If the rib
spacing is 300 mm or more, metal deck shall be fastened at the bottom of every
rib.
All ends or
butt ends of metal decking shall be fastened to the supporting structural
members.
The side laps of metal decking shall be fastened at
not more than 915 mm on centers.
When fusion welds are used for fastening, they shall
have diameters of not less than 19 mm and shall be free of sharp points or
edges.
Where the ribs of metal deck are parallel to and
directly supported by steel beams, the bottom of ribs or side closures shall be
fastened to steel beams with 19 mm diameter fusion welds at a maximum of 915 mm
on centers.
Fasteners and welding shall be confirmed to the
requirements of Book IIIA, section “Welding in Steel
Structures”.
TEMPORARY SUPPORTS
The Contractor shall be responsible for designing,
furnishing, installing and removing any temporary supports required to support
the additional construction loads resulting from his work, with reference to
Book IIIA, Section 4.4.3.
FIELD TOUCH-UP PAINTING
Field cut
edges, scratches etc. in metal decks shall be field touch-up painted with one
coat of zinc-rich paint comparable with shop galvanizing.