STEEL STRUCTURES : STEEL STRUCTURES BY
B.ARCH-11/05 STEEL : STEEL Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight (C:110–10Fe), depending on grade.
Melting point-2750 degree F.
Durability, flexibility and strength, lend itself to many varied
uses, one of which is in construction.
The choice of structural steelwork system as an alternative to reinforced concrete structures has many advantages.
Steel can be easily formed and joined and its strength to weight ratio is the highest among common building materials.
Steel can also be recycled and is a good alternative
building material that contributes to sustainable construction. BUILDINGS WITH ACCURATE TOLERANCES : BUILDINGS WITH ACCURATE TOLERANCES Steel buildings can be built with better tolerances and quality and are longer lasting ARCHITECTURAL AESTHETICS : ARCHITECTURAL AESTHETICS The use of steel structures permits designers to experiment with many architectural forms and artistic expressions which are more difficult to build in conventional concrete framed structures.
With steel, more challenging and creative designs can now be considered leading to buildings that are aesthetically distinctive and of high build quality STEEL BUILDING : STEEL BUILDING A steel building is a metal structure with steel for the exterior cladding and internal support. Such buildings are used for a variety of purposes including storage, office space and living space.
Low maintenance costs
Components can be re-used
Components are functional
Strong, durable and stable
Enables good design and safety
Sustainable to temperature effects
Rigid and dimensionally stable
Construction is fast compared to other materials
Resistant to termites and other destructive insects
Cheaper than any other construction methods
Offers fast construction DISADVANTAGES : DISADVANTAGES Heat conductivity
Corrosion--Faulty design leads to the corrosion of iron and steel in buildings. STRUCTURAL STEEL : Structural steel is steel construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and strength.
Structural steel shape, size, composition, strength, storage, etc, is regulated in most industrialized countries.
Structural steel members, such as I-beams, have high second moments of area, which allow them to be very stiff in respect to their cross-sectional area. STRUCTURAL STEEL Common structural shapes : Common structural shapes In most developed countries, the shapes available are set out in published standards, although a number of specialist and proprietary cross sections are also available in India
HSS-Shape (Hollow structural section) also known as SHS (structural hollow section) and including square, rectangular, circular(pipe) and elliptical cross sections)
Angle (L-shaped cross-section)
Channel (C-shaped cross-section)
Tee (T-shaped cross-section)
Rail profile (asymmetrical I-beam)
Plate, sheet metal thicker than 6 mm or 1/4 in.
Open web steel joist
While many sections are made by hot or cold rolling, others are made by welding together flat or bent plates. : FASTENERS : FASTENERS Basic types of fasteners are typically used in construction, bolts ,rivets and welds.
Both are used in the fabricating shop and on the job site in connections joining individual members.
Welds are also used to fasten together components of built-up members.
Bolts, however, are more commonly used for field connections, and welds, for shop work. FLOOR-FRAMING DESIGN CONSIDERATIONS : FLOOR-FRAMING DESIGN CONSIDERATIONS Selection of a suitable and economical floor system for a steel-frame building involves many considerations: load-carrying capacity, durability, fire resistance, dead weight, overall depth, facility for installing power, light, and telephones, facility for installing aid conditioning, sound transmission, appearance, maintenance, and construction time.
Durability becomes a major consideration
Resistance to lateral forces should not be disregarded.
The most common types of flooring are (a) concrete fill on metal deck,(b) pre-cast concrete plank, and (c) cast-in-place concrete floors with integral joist. LONG-SPAN FRAMING : LONG-SPAN FRAMING When the clear distance is greater than can be spanned with rolled beams, several alternatives are available.
These may be classified as girders, simple trusses, arches, rigid frames, cantilever-suspension spans, and various types of space frames, such as folded plates, curvilinear grids, thin-shell domes, two-way trusses, and cable networks. ROOF FRAMING SYSTEMS : ROOF FRAMING SYSTEMS In fact, for flat-top tier buildings, the roof may be just another floor. However, when roof loads are smaller than floor loads, as is usually the case, it may be economical to lighten the roof construction.
For example, steel joists may be spaced farther apart. Where roof decking is used, the spacing of the joists is determined by the load-carrying ability of the applied decking and of the joists.
Most of the considerations discussed for floors in also are applicable to roof systems.
In addition, however, due thought should be given to weather resistance, heat conductance and insulation, moisture absorption and vapor barriers, and especially to maintenance. SPECIAL STRUCTURES : SPECIAL STRUCTURES Three-Hinged Arches
Stresses in Arch Ribs
Ribbed and Hooped Domes
Simple Suspension Câbles
Cable structural systems
Folded Plates (space frames)
Orthotropic Plates 3-HINGED ARCHES : 3-HINGED ARCHES An arch is a beam curved in the plane of the loads to a radius that is very large relative to the depth of section.
Loads induce both bending and direct compressive stress. Reactions have horizontal components, though all loads are vertical.
Deflections, in general, have horizontal as well as vertical components. At supports, the horizontal components of the reactions must be resisted.
For the purpose, tie rods, abutments, or buttresses may be used. 2-HINGED ARCH : 2-HINGED ARCH A two-hinged arch has hinges only at the supports .Such an arch is statically indeterminate. FIXED ARCHES : FIXED ARCHES In a fixed arch, translation and rotation are prevented at the supports .Such an arch is statically indeterminate. Slide 19: STEEL TRUSS FRAME
IN THE EXTERIOR PLATE DOMES : PLATE DOMES A dome is a three-dimensional structure generated by translation and rotation or only rotation of an arch rib. Thus a dome may be part of a sphere, ellipsoid, paraboloid, or similar curved surface.
Domes may be thin-shell or framed, or a combination. Thin-shell domes are constructed of sheet metal or plate, braced where necessary for stability, and are capable of transmitting loads in more than two directions to supports. : RIBBED DOMES : RIBBED DOMES One type of framed dome consists basically of arch ribs with axes intersecting at a common point at the crown and with skewbacks, or bases, uniformly spaced along a closed horizontal curve. RIBBED AND HOOPED DOMES : RIBBED AND HOOPED DOMES SCHWEDLER DOMES : SCHWEDLER DOMES CABLE SUSPENSION SYSTEMS : CABLE SUSPENSION SYSTEMS PLANE-GRID FRAMEWORKS : PLANE-GRID FRAMEWORKS A plane grid comprises a system of two or more members occurring in a single plane,interconnected at intersections, and carrying loads perpendicular to the plane.
Grids comprised of beams, all occurring in a single plane, are referred to as single-layer grids.
Grids comprised of trusses and those with bending members located in two planes with members maintaining a spacing between the planes are usually referred to as double-layer grids. : FOLDED PLATES : FOLDED PLATES Planar structural members inclined to each other and connected along their longitudinal edges comprise a folded-plate structure SPACE FRAMES : SPACE FRAMES Space frames are three dimensional lattice-type structures that span in more than one direction.
Space frames spanning over large column-free areas are generally supported along the perimeter or at the corners.
The depth of a space frame is generally 4 to 8% of its span.
To effectively utilize the two-way spanning capability of a space frame, the aspect (length-to-width) ratio should generally not exceed 1.5:1.0.
In addition to providing great rigidity and inherent redundancy, space frames can span large areas economically, providing exceptional flexibility of usage within the structure by eliminating interior columns.
Space frames possess a versatility of shape and form. They can utilize a standard module to generate flat grids, barrel vaults, domes, and free-form shapes. : GATEWAY MADE OF SPACE FRAME WELDED JOINT SUPPORTING CABLES EXAMPLE : EXAMPLE GMR INTERNATIONAL AIRPORT,HYDERABAD. INTERNATIONAL AIRPORT,HYD : INTERNATIONAL AIRPORT,HYD The new Rajiv Gandhi International Airport is located at approximately 22km from Hyderabad city, one of the fastest growing cities and the sixth-largest metropolitan area in India.
The new 100,000m² terminal building can accommodate an initial capacity of 12m passengers per year
The Passenger Terminal Building comprises a 5-level reinforced concrete frame supported on pad foundations, covered with a structural steelwork roof with spans up to 45m length.
A lightweight fabric roof structure covers the pick and drop off areas along the frontage access to the airport. The design has provided flexibility to enable future expansion that will ultimately cater for over 40m passengers per annum. Slide 39: TENSILE FABRIC ROOF COATED WITH WEATHER PROOF MATERIAL -COVERING ON SPACE FRAME ROOFING Slide 40: SPACE FRAME Slide 44: PICTURE SHOWING STEEL TRUSS USED IN THE FRONT LOUNGUE Slide 45: NATURAL LIGHTING THROUGH THE SPACE FRAME TRUSSED ROOF Slide 46: INTERIOR ROOFING Slide 47: STEEL TRUSS FRAME
IN THE EXTERIOR