Fig 74- Hour Activation Diagram

Superstructure: Steel Structure Systems

There are two sorts of steel elements: Hot-rolling is used to mould relatively heavy structural steel elements into their final shapes. Wide-flange sections, angles, channels, bars, and plates are all made using this process. Cold-formed light-gauge steel framing members are made from thin sheets or rods. Roof and floor decking, as well as a range of light frame members such as channels, studs, and joists, are examples.

Structural Steel Framing

Traditional hot-rolled structural steel is a versatile material with uses ranging from single-story buildings to the world’s tallest structures. Because of the amount of prefabrication often utilised with structural steel, the method is precise and quick to build.

Structural Steel Hollow Column

The top chart is for hollow steel section columns up to 12 ft (3.7 m) tall between floors. Read in the top open areas for light and medium loads. Read in the lower solid areas for heavy loads. Total tributary area is the summed area of the roof and all floors supported by the column.

Fig 113- Composite Steel Deck Slab Source- The Architect’s Studio Companion- Rules of Thumb for Preliminary Design

Structural Steel Beams and Girders

This chart is for steel wide-flange beams, composite beams, and girders. For average and light loads, read toward the right in the indicated areas. For heavy loads, read toward the left.

Fire- Resistance Ratings for Steel Beams and Girders

Steel beams and girders may be used in both Combustible and Noncombustible Construction. Fire-resistance ratings of as high as 4 hours are achievable with applied fireproofing or an appropriately fireresistive ceiling. Some building codes also allow reduced fire protection or exposed steel for roof structures that are 15 to 25 ft (4.6 to 7.6 m) or more above the floor.

Superstructure: Composite Slab

Whether the beams are downstand or integrated within the slab depth for a shallow floor type of construction, composite slabs, made of lightly reinforced concrete cast on profiled steel decking, are an option. In most cases, the slabs are reinforced with an upper layer of mesh and, in certain cases, extra bars in the troughs (usually for longer periods of fire resistance and heavy loads). Fibre reinforcement is another option. Trapezoidal decking can support spans of up to 4.5 metres (80 mm deep). Deep decking profiles (over 200 mm deep) are also available, which can span 6 m or more without the need for propping during construction.

Once installed, the decking provides additional benefits, such as serving as a working platform and a storage area for products. It can prevent lateral torsional buckling if it is properly oriented and fastened to the steel beams. In their ultimate state, the decking ribs act as void formers in the slab, lowering the weight of the floor structure and providing other benefits. Anchors designed to slot into the decking profile can also be used to suspend services from the soffit of a composite slab.

Fig 114- Composite Steel Deck Slab Source- https://www.steelconstruction.info/Composite_construction#Composite_slabs

Types of Decking

How and why composite construction works?

The two materials must be structurally connected together for the concrete part (within the socalled effective width) of a cross section to carry compression and the steel part to carry tension. For downstand beams, this is accomplished with pointed shear studs affixed to the steel beam’s upper flange. This is usually accomplished through the use of so-called through deck welding. The profiled metal decking that serves as the foundation for the composite slabs is sandwiched between the stud’s base and the top flange, and all three are joined by welding. The presence of galvanising on the decking has no bearing on the quality of the welds.

The advantage of structurally linking the steel and concrete beams is that it increases the resistance of the steel beam alone by around a factor of two. It’s possible that the stiffness will increase by a factor of three. As the span of the steel beam grows larger in comparison to the slab, the relative benefits decrease.

Floor Decking Sizes

The top chart is for corrugated or cellular steel floor decking with concrete slab topping. For light loads, read toward the bottom in the indicated areas. For heavy loads, read toward the top.

The bottom chart is for corrugated steel roof decking. For light loads, read toward the right in the indicated areas. For heavy loads, read toward the left.

Fig 115- Composite Steel Deck Slab Source- The Architect’s Studio Companion- Rules of Thumb for Preliminary Design

Superstructure: Truss

Economical Span Ranges for Trusses

Parallel chord trusses are most economical for spans up to 120 to l40 ft (35 to 45 m) due to the increased difficulty of shipping elements greater than 12 ft (3.7 m) deep. Triangular and bowstring trusses can be shipped at slightly greater depths. Trusses spanning 300 ft (90 m) or more may be shipped in sections and assembled on site.

Fire-Resistance Rating for Steel Trusses

Structural steel trusses may be used in both Combustible and Noncombustible Construction. Fire-resistance ratings of as high as 4 hours are achievable with applied fireproofing or an appropriately fire-resistive ceiling. Some building codes also allow reduced fire protection or exposed steel for roof structures that are 15 to 25 ft (4.6 to 7.6 m) or more above the floor.

Superstructure: Concrete Stands

Water, aggregate (rock, sand, or gravel), and Portland cement are the three main components of concrete. When mixed with water and aggregates, cement, usually in powder form, works as a binding agent. This mixture, or concrete mix, will be poured and solidify into the long-lasting material we’re all familiar with.

Proportioning

The proportioning and mixing of the materials is crucial to generate a strong, concrete. It will be difficult to position a combination that does not have enough paste to fill all of the spaces between the aggregates, resulting in rough surfaces and porous concrete. A mixture with too much cement paste is easy to work with and produces a smooth surface; nevertheless, the resulting concrete is not cost-effective and is more prone to cracking. The character of the concrete is determined by the paste quality. The strength of the paste is determined by the water-to-cement ratio.

Fig 116- Constructing Concrete Slabs Source- https://www.cement.org/cement-concrete-applications/how-concrete-is-made