SCOPE
OF WORK
The scope of work shall be in accordance with BOOK II
Subsection "Summary Scope of Work" and Book
III A refers to "General
Civil and Architectural Design Requirements".
Design and fabrication of structural steel, as defined in
the AISC Code of Standard Practice, shall conform to the requirements of this
Section, and all applicable requirements of the AISC Manual of Steel
Construction, latest edition unless otherwise indicated. The Work shall include
the following:
§
Designing,
furnishing, fabricating and delivering structural steel and crane rails
including floor loading signs.
§
Designing,
furnishing, fabricating and delivering gallery and auxiliary steel.
§
Designing and furnishing shop and field
connections included in the structural, steel.
§
Verifying
field measurements for fabrication as required.
INTENT OF SPECIFICATION
The work covered by the specification
shall include full provision for the following:
All
structural steel, columns, girders, beams, bracing, base plates, column anchor
bolts, trolley beams and other materials as required for the support of the
buildings, structures, ducts, equipment, piping and other appurtenances above
the foundations at grade.
With respect to drawings included in
the bid of the offer Document, the following terms shall be clearly understood:
Work indicated on those drawings shall
be used only as a guide for the type of steel work which will be required for
the Work; actual sizes, weights, thickness, relative quantities of various
classes etc. shall be based on Contractor's detailed design drawings.
Cost
incurred as a result of changes due to Contractor's design need,
misinterpretation of design intent, miscalculation of connections or other
design, detailing and fabrication errors shall be Contractor responsibility.
CODES
AND STANDARDS
The Contractor shall comply with the requirements of Book
II, Subsection 'Codes and Standards'.
The codes and standards of the following organizations
extracted from Book II, Subsection 'Codes and Standards' are specifically
applicable to the design, manufacture and testing of the work included in this
Specification:
AISC
………. American Institute of
Steel Construction
ANSI
………. American National
Standards Institute
AREA
………. American Railway
Engineering Association
ASTM
……….. American Society for
Testing and Materials
AWS
……….. American Welding society
SSPC
………… Steel Structures Painting Council, USA
UBC
..………. Uniform
Building Code of USA
REPORTS
AND CERTIFICATES
Copies of material certifications, mill test reports, and
other reports required by applicable codes or standards shall be available from
the Contractor. Those reports shall be submitted as requested by the Owner
after completion of the required tests.
MATERIALS
-All materials for the power plant
buildings and other structures shall conform to the requirements of the
Contractor's design drawings, Table 4.4.2.14 ‑1 and 4.4.2.14 ‑2 or approved
equal.
-Hot rolled steel of wide flange shapes
with 600 min or less depth shall be of local origin as long as available.
Table
4.4.2.14‑1 MATERIAL FOR STRUCTURAL STEEL WORK
Item
No.
|
Material
|
ASTM Standards
Codes Unless Noted
|
1.
|
Hot rolled beams, bars, channels,
plates
and angles, bracing, structural tees
|
A36
|
2.
|
Plate girders
|
A36
|
A572 Grade 50
|
||
A588 Grade 50
|
||
A588 Grade 46
|
||
A588 Grade 42
|
||
3.
|
Columns
|
A36 or A572 or A588
|
4.
|
Cover plates
|
A36 or
A572 Grade 50
A588 Grade 50
|
5.
|
Column base plates and splice plates
|
A36
|
6.
|
Connection bolts
|
A325F
|
7.
|
Welding
|
AWS D 1.1
|
8.
|
Column anchor bolt
|
A36 or
A307 or
A193 Grade B7
|
9.
|
Round tubular bracing
|
A53
|
10.
|
Square and rectangular tubing
|
A500, Grade B or A501
|
11.
|
Castings
|
A27, Grade 65-35 or
A148, Grade 80-50
|
12.
|
Forgings
|
A668, Classes C, E and F
|
13
|
Crane rails
|
BS 11 or equivalent
|
Note: For additional requirements for
material see Table 4.4.2.14‑2
Table
4.4.2.14‑2 ADDITIONAL REQUIREMENTS FOR STRUCTURAL STEEL MATERIALS
Material Item
|
Standard
|
Additional Requirements
|
1. Structural
|
ASTM A36
|
Use for- all structural steel other
than steels specifically indicated in this
|
specification
|
||
2. High-Strength
|
a.
ASTM A572
|
Grade, as required.
|
Steel
|
b.
ASTM A588
|
Use yield as required.
|
3. Low-Sulfur
High-Strength Steel (for plates over
12 mm in thickness)
|
ASTM A588 Grade
|
a. The sulfur content of the steel
shall be 0.010% maximum, and the sulfides shall be in globular forms.
|
A or B A572 Grade
|
b.The steel shall have the following
properties in through thickness direction:
|
|
50 with special process (such as
vacuum degassing)
|
b1.
Reduction of area under tensile test shall be 25% minimum.
|
|
b2. The yield and tensile strengths
shall be not less than 75% of specified strengths of original A588 or A572. For
plates thicker than 56 mm, yield tests shall be performed with test specimens
conforming to ASTM A370 Figure 5 for 12 mm dia specimens.
|
||
c. The steel shall be 100%
ultrasonically
|
||
tested, per ASTM A578 Level I for
plate thickness of 19 mm and greater, and level 11 for plate thickness less
than 19 mm, except that a 25 mm dia. Circle shall be used instead of 75 mm
dia. Circle, and scanning shall be continued over 100% of the plate surface.
|
||
d. The steel shall be tested for
Charpy
V- Notch Impact, in accordance with
|
||
ASTM A370 with frequency (P)
indicated in ASTM A637; and shall
meet the following requirement:
|
Direction Charpy Value
(Mils-lateral
expansion)
At 00C
|
||
Longitudinal 70
Transverse 60
Through-Thickness 30
|
||
e. Use: Where indicated, especially
for plates loaded or stressed in through thickness direction.
|
||
4 Stainless Steel Hot rolled, annealed
and pickled (HRAP) finish
|
a. ASTM A240,
b. ASTM A240, conforming to A358, Class
1, Grade 304
|
Plates
Plates for fabrication of welded
plate piping included in structural steelwork.
|
5. Stainless-Clad Steel, with finish,
RMS values of 10 to 30
|
ASTM A240, Type 304 stainless
cladding steel on backing plate of ASTM A36 steel, Conforming to ASTM
|
Thickness of cladding shall be nominal 1.2
mm single clad for backing plates 6 mm or more in thickness.
|
6. Tubular members
6.1Round tubular
Bracing
|
ASTM A53 of the following type and
grade:
a. Type E or S, open hearth or basic
oxygen steel only, with sculpure Content not exceeding 0.05%
b. Grade B only (2,460 kg/cm2
yield)
|
Use standard, extra strong or double
extra strong weight.
|
6.2Rectangular or Square Tubing
|
ASTM A500 Grade B or A501
|
For tubular framing
|
Table
4.4.2.14‑2 ADDITIONAL REQUIREMENTS FOR STRUCTURAL STEEL MATERIALS (CONT’D)
Material Item
|
Standard
|
Additional Requirements
|
7.High-Strength Bolts
|
AISC Specification for Structural
Joints Using ASTM A325
|
a. Bolts and Nuts: Use the
following materials unless otherwise indicated
a.I. For bolts sizes use A325,Type.1
steel.
|
b.
Washer:
|
||
A325 Bolts: One washer under the head or or nut whichever is the element turned in
tightening.
|
||
8 Shoulder bolts for slotted sliding
connection.
|
||
8.1 Bolts
|
ASTM A325, Type 1
|
22 mm diameter shank; grip length of
|
bolt shall equal the thickness of the
mated parts plus two 3 mm thick washers plus 3 mm. Bolt threads shall be 19
mm diameter and the length shall equal the thickness of two nuts plus 6 mm.
|
||
8.3 Washers
|
ASTM F436
|
Two 22 mm diameter washers required.
|
One washer under the bolt head and
one under the nut.
|
||
9.
Castings
|
a. ASTM A27, Grade
|
Use for all castings unless otherwise
|
65-35.
|
indicated.
|
|
b. ASTM A148, Grade
|
Use only where high strength steel
|
|
80-50.
|
castings are required.
|
|
10. Forgings
|
ASTM A688, Classes C, E and F
|
Use for all forgings unless otherwise
indicated.
|
11. Stock Material
|
As specified in Items 1
|
Mill test reports for applicable
material
|
through 10
|
shall ordinarily constitute
sufficient
|
|
record, but separate tests may be
|
||
required on pieces selected from any
|
||
shipment.
|
Table
4.4.2.14 ‑2 ADDITIONAL REQUIREMENTS FOR STRUCTURAL STEEL MATERIALS (CONT’D)
Material Item
|
Standard
|
Additional Requirements
|
12. Crane
Rails-weight 50 Kg/m or more. (Lighter rails shall conform to manufacturer
standards).
|
ASTM A1, No. 1, Rails with carbon content 0.67-0.82% or
manufactures standards meeting the same required
|
a. Product: Shall be control cooled and heat
treated or end hardened, as made by one of the following manufactures or
approved equal in accordance with their standard specification for crane
rails, unless otherwise indicated:
a.1. Bethlehem Steel Corporation, USA
a.2. United States Steel Corporation
b. Length: Standard 12 m, subject tolerance of
ASTM A1.
c. Size: As indicated on the design drawings.
d. End Drilling: Three holes each end, spaced to suit
specified joint bars and as required for tight end joints.
e. Marking: As specified in ASTM A1.
|
13. Crane Rail
Accessories
|
As indicated
|
Accessories shall be as made by, or as furnished by, one
of the rail manufacturers indicated in item 12 in accordance with their
standard specifications for rail accessories, for the specified rails and in
accordance with the requirements of this Item 13.
|
13.1
Joint Bars
13.2
Bolts and Nuts
13.3
Spring Washers
|
ASTM A3
ASTM B325 and
ANSI B18.2
AREA Specification
For spring washers.
|
Low-carbon steel, with 6 holes and
with size and shape of bars and spacing of holes as required for tight end
joints
Heat-treated, with finished hexagon
heads in accordance with ANSI B 18.2
Alloy steel with one washer for each bolt.
|
Table
4.4.2.14 ‑2 ADDITIONAL REQUIREMENT FOR STRUCTURAL STEEL MATERIALS (CONT'D)
Material Item
|
Standard
|
Additional Requirements
|
13.4 Rail Clips
|
ASTM A36 or better
|
Shall be "Tight Fit" type,
made of pressed steel plate with reversible steel fillers and 2 holes each
clip.
|
Also it shall be designed to allow
for the
|
||
resilient pad and lateral adjustment
of the crane rail of ± 5 mm relative to the crane girder, during and after
installation.
|
||
13.5 Resilient Pad
|
The resilient pad under the crane
rails shall be manufactured from
synthetic elastomer and be resistant –o wear, shear, crushing, oil, grease,
oxygen and ultra violet rays and shall be reinforced along its length with a
steel strip.
|
|
DESIGN
GENERAL PROVISIONS
The design of all structural steel required by this Contract
and the design work for all shop and field connections, including angles,
welds, web reinforcement for coped beams, gusset plates and bolts shall be
performed by Contractor. The Owner prior to fabrication shall submit the design
and shop drawings including typical calculations for each connection type for
review. Such review shall in no way be
interpreted as constituting approval of the adequacy of such design for their
intended use and shall not relieve Contractor of correctness and of complete
design responsibility and from fulfilling all obligations under the Contract.
All design calculations and drawings shall be prepared under
the supervision of a qualified Engineer.
DESIGN REQUIREMENTS
The
design of structural steel shall conform to all applicable requirements of the AISC Manual of Steel Construction, latest
edition and also conform to the requirements of the following specifications:
"Structural Descriptions and Criteria" Book IIIA,
Section 4.4.3
"Welding in Steel Structures"
Book IIIA, Section 4.4.2.20
"Erection of Structural
Steel" Book IIIA, Specification 4.4.2.15
The connections shall be designed to
resist ultimate moments, shears and axial forces of connected members.
Prying action shall be considered in
the design of bolted connection‑s in accordance with the AISC Manual of Steel
Construction.
The
following allowable stresses specified in the AISC Specification for Structural
Joints Using ASTM A325 bolts shall be
used in connection bolt
design:
Allowable
stresses for blast‑cleaned surfaces (for shop welded and field bolted
connections).
Allowable
stresses for mill scale surfaces (for shop bolted and field bolted
connections).
FABRICATION
GENERAL PROVISIONS
Conformance
Fabrication of structural steel shall
conform to all applicable requirements of codes and standards and other
standard specifications specified this section, and to all requirements.
FABRICATION REQUIREMENTS FOR PLUMBING
UP AND LEVELLING
The structures shall be plumbed and
leveled such that deviations in the completed work do not exceed the
requirements of the AISC Code of Standard Practice.
These requirements shall be fully
considered in fabrication, and Contractor's shop erection drawings shall be
clearly marked with these restrictions.
MISFITS
Attention is specifically directed to
the requirements of the AISC Code of Standard Practice and Quality Criteria and
Inspection Standards, with respect to correction of fabrication errors. Any
errors in shop work which prevent proper field assembly (and fit up will be
reported, as soon as they are discovered to the Owner and to the fabricator by
the Contractor. The Contractor shall then make immediate substitutes or arrange
for correction at no cost to the Owner.
The allowable limits for reaming the
connection bolt holes for fit up in the shop or in the field shall conform to
the requirements of the AISC Quality Criteria and Inspection Standards. If fit
up of bolts during erection in the field cannot be obtained by reaming the fabricated bolt holes within these
limits, it is considered that there are errors in fabrication, and these errors
shall be rectified in accordance with previous paragraph.
CONNECTIONS
All connections shall be welded or high
strength bolted, in the shop or field as follows:
Shop Connections
All members and details shall be
fabricated by welding or high strength bolting, using FRICTION TYPE
connections; and welding may be used in combination with the high strength
bolting completed prior to welding.
The Contractor shall submit with his bid proposal, a
schedule of where he proposes to use each method of fabrication, and in general
the members, connections, etc. Included under each method.
Field Connections
All connections shall be made with high‑strength bolts,
using FRICTION TYPE connections, unless otherwise indicated.
Welding
Conformance
Welding, including stud welding, shall
conform to the requirements of Specification refers to "Welding in Steel
Structures"
Welding Drawing
All welding shall be clearly indicated
on the shop drawings.
Field Welding Preparations
Contractor shall provide all end and
edge preparations for field welding.
High Strength Bolting
Conformance
High strength
bolting shall conform to the applicable requirements of the AISC Specification
for Structural Joints Using ASTM A325 Bolts for friction type connections, and
to the requirements of this Clause. Unless otherwise indicated.
Bolt Types
Shall be as
indicated in Table 4.4.2.14 ‑2.
Bolt Holes
Shall be 1.5 mm
larger than the nominal diameter of the bolt. Larger or slotted holes will not
be permitted unless otherwise indicated.
Long Grips
Additional high‑strength bolts are not
required for long grips.
Installations
a.The turn‑of‑nut tightening or
calibrated wrench tightening methods, as specified in the AISC Specification
for Structural Joints Using ASTM A325 Bolts, shall be used. The use of a direct
tension indicator for tightening will not be permitted.
b.The minimum projection of the
installed bolt beyond the nut shall be 6 mm.
cThe threaded part of the installed
bolt shall not be in the shear plane.
d.Blouse of torque bolts will not be
permitted.
Beam Connections
Connection Types
Shall conform to the AISC
Specification, Part 4.
Connection Angles
a.
Connection
angles shall be minimum 10 mm thick.
b.
Connection
angles for any deep girder shall be continuous from the top flange to the
bottom flange in all cases.
c.
Usual
gauge as presented by AISC shall be used. Bolt staggering shall be used only to
maintain the usual gauge.
Knife Connection
This connection, consisting of
two-connection angles shop assembled to receive the web of a beam in field
erection, shall not be used.
MISCELLANEOUS DETAILS
Welded Cover Plates on Columns and
Girders
Cover plates on each flange of columns
or girders shall be a single plate in each thickness.
Bracing
Vertical diagonal bracing members shall
be wide flange shapes, double angles, double channels or tubular. Horizontal
bracing shall be single angles.
Tubular Bracing
a. Tubular
bracing used for indoor work (not exposed to the elements) shall be open‑ended.
b. Tubular
bracing used for exterior work (exposed to the elements) shall have the top end
capped and the bottom end open. Cap plates shall be 6 mm thick and continuously
welded all around the bracing.
Draw for Single-Angle Cross Bracing
Long single angle cross bracing members
shall be fabricated with a draw or reduction in the actual distance center to
center of end connection bolt holes (as compared to the theoretically correct
distance) as indicated in following Table 4.4.2.14 -3; no draw shall be
provided for double angle, tubular or other shape bracing:
Table 4.4.2.14 -3 DRAW REQUIREMENTS FOR SINGLE ANGLE BRACING
Length
|
Draw
|
0 To 3.5 m
Over 3.5 m to 7 m
Over 7 m to 10 m
Over 10 m
|
-
1.5 mm
3 mm
4.5 mm
|
Double Angle Bracing
All double-angle bracing members have
long legs back-to-back unless otherwise required.
Camber
Built-up girders, trusses and rolled
beams shall be fabricated to provided for camber in accordance with the
requirements of the AISC Manual of Steel Construction.
Column Splice Milled Ends
These ends shall not be out of square
more than 0.75 mm, as specified in ASTM A6 Table 24. However, only milling
techniques shall be used in this fabrication.
Curb Angles and Guard Plates
Connect curb angles and guard plates to
the structural steel in the shop.
Guard plates shall be furnished in as
large lengths as possible, with joints not closer than 90 cm to handrail posts.
Cutouts where required to clear indicate piping, or other equipment, etc.,
shall be provided.
For adjoining guard in continuous runs
or at corners, the ends shall be tack-welded together at the top.
Frames for Removable Concrete Slabs
Angle frames shall be furnished for
removable concrete slabs supported on structural steel framing. Contractor will
provide lifting inserts for these slabs. Angles shall have headed studs for
sound anchorage in concrete.
Hangers
All hangers shall have a minimum of two
high-strength bolts at each end.
Trolley Beam Stops
Each trolley beam stop shall consist of
two 75 mm x 75 mm x 12 mm angles, each of which shall be connected to the beam
with two 18 mm diameter machine bolts. Each bolt shall have hexagon head and
one heavy hexagon nut.
Girts
Extent
Girt shall include horizontal girt,
carrier girt, girt posts, door and window framing attached to girt, parapet
framing, sag rods etc.
Plumb and Level
Girt shall be fabricated to the same
plumb and level requirements as specified in paragraph above.
Frames Around Openings
Girt around doors, windows, and louver
openings shall be fabricated in accordance with the following requirements:
a. All corners of
openings formed by junctions of vertical and horizontal girt members shall be
absolutely square.
b. Vertical and
horizontal dimensions of openings shall each be within an overall tolerance of
± 1,5 mm for doors, ± 6 mm for windows, and + 6 mm, to 0 mm for louvers.
c. The junctions of
vertical and horizontal girt members at the head arid sill of door openings
shall be detailed with end clearances not exceeding 6 mm nor less than 3 mm,
and shall be arranged for field welding closured, of these junctions.
d. Head angles for
windows shall be detailed with end clearances not exceeding 6 mm, nor less than
3 mm; these clearances shall apply for intermediate joints in continuous runs
of head angles, and also for joints of junctions of the head angle and jamb
angle. Also, these joints shall be
detailed for field welding closures.
e. Fill
plates at the junction of jamb angles and sill angles shall be provided, and
shall be detailed for field welding closures of these junctions.
f. Steel
channel doorframes may be shipped knocked-down for field-welded assembly or may
be completely shop-assembled and shipped as a unit.
Connections
Each connection for a girt shall have a
minimum of two 16 mm diameter high-strength bolts unless otherwise indicated.
Sag Rods
All sag rods shall have two heavy
hexagon nuts each end. Holes for sag
rods shall be 1.5 mm larger than the nominal diameter of the sag rods. Larger
holes up to 4,5 mm larger than the road diameter will be permitted only if a
hardened washer is used with each nut on each side of these holes.
Stainless-Clad Steel
Edge Preparation and Welding
a. Prior to
fabrication, The Contractor shall consult with the manufacturer to ensure the
best possible fabrication of the material for the intended purpose. All joints
shall be of welded construction unless otherwise indicated and the welding
shall be done on both the stainless-clad and backing sides.
b. Only electrodes
recommended by the manufacturer for stainless clad steel shall be used for all
welding on the stainless clad side of the material. The stainless steel side
shall be back gauged or ground to bright sound metal prior to welding. All
welding operations shall be performed so as to reduce to a minimum, or
completely eliminate, all weld spatters on the stainless-clad side. Also use
anti spatter compound along both edges of welded joints, on the stainless-clad
side, to permit easier removal of any spatter that does occur, hard, brittle
weld is not acceptable.
c. Grinding of welds
will not be required except as necessary to remove sharp edges; however, all
welds shall be made as neatly as possible. Pits, crevices and other
discontinuities shall be corrected by the use of additional weld metal if
required.
Protection
a. The
manufacturers shall ship the material in bundles suitable for handling, with
wood laths separating each plate. Wrap
each group of plates that make up a bundle shall be completely wrapped in heavy
waterproof Kraft paper and steel banded for shipment.
b. Upon
receipt of material, leave the plates packaged until the plates are required
for fabrication.
Special Precautions
a. Any temporary
materials, such as handles of lifting lugs etc. shall not be attached to the
stainless-clad side of material.
b. Any scratches,
gouges or damages to stainless-clad surfaces shall be satisfactorily by the
Contractor at his own expense. Gouges and scratches 0.75 mm deep or less and;
those deeper than 0,75 mm fill with weld metal, as specified for welding of
stainless-clad steel, and shall be ground and hand-buffed smooth. Weld spatter
or other deposits on surfaces shall be carefully removed flush with the
surfaces, and these areas shall be hand-buff these areas smooth.
Inspection
Inspect all stainless-clad material
shall be inspected, after completion of fabrication, by the Contractor, or by a
testing laboratory inspector furnished the by Contractor, for full compliance
with all requirements herein specified.
Any work not conforming to specified requirements shall be
satisfactorily repaired, before the material is shipped.
Crane-Rails
Rail lengths shall
be fabricated so that rail joints on opposite sides of the runway are staggered
with respect to each other. Rail joints shall not coincide with the joints
occurring in the runway support girders.
Rail shall be
milled or grind rails to provide tight joint assembly.
Rail clips shall
be tight fit type rail clips in pairs spaced at 60 cm on centers.
SHOP CLEANING AND PAINTING
Shop cleaning and painting including
surface preparation of structural steel shall conform to all applicable
requirements of specification refers to ''Prime Cost and Shop Painting, and
Field Painting".
All trolley beam
surface shall be painted yellow with one shop prime coat of paint. The design
capacity of each trolley beam shall be stenciled on both sides of the web at
the approximate mid span of each beam, using the notation “CAPACITY TONS”
lettered in 75 mm high block letters, with black paint. The surface
preparation, painting and paint product/manufacturers shall conform to the
applicable requirements of Design and Fabrication of structural steel.
Correction of Painting Work
Painted surfaces of structural steel
will be inspected, as specified in specification refers to “Prime Coat and Shop
Finish Painting” in the field after a reasonable period of weathering. If the
condition of any surface indicates insufficient thickness of paint was used, or
method of application was incorrect, etc. (regardless of prior approval of the
work in the shop), Contractor shall repaint all such surface in the field as
requested.
The foregoing requirement shall not
apply with respect to surfaces abraded in shipping, handling etc. for which
field touchup painting will be performed by the Contractor.
QUALITY
ASSURANCE/QUALITY CONTROL (QA/QC)
The quality control procedures so
specified shall include but not be limited to the following:
- Material certificates
- Welding
- Non distributive testing
- Shop test and inspection procedures
- Cleaning and painting
- Packaging and shipping
The Quality Control documentation as
specified above shall include but not be limited to the following:
- Material certificates
- Welding procedures
- Shop test and inspection reports
INSPECTION
AND TEST AT SHOP
The Contractor shall submit a work
inspection and test program covering all materials and equipment to the
Owner. Agreement is to be established on
the degree of inspection and test to be witnessed by the Owner or his
representative before start and during the course of work.