Low Cost Housing is a new concept which deals with effective budgeting and following of techniques which help in reducing the cost construction through the use of locally available materials along with improved skills and technology without sacrificing the strength, performance and life of the structure.There is huge misconception that low cost housing is suitable for only sub standard works and they are constructed by utilizing cheap building materials of low quality.The fact is that Low cost housing is done by proper management of resources.Economy is also achieved by postponing finishing works or implementing them in phases.

Building Cost
The building construction cost can be divided into two parts namely:
Building material cost : 65 to 70 %
Labour cost : 65 to 70 %
Now in low cost housing, building material cost is less because we make use of the locally available materials and also the labour cost can be reduced by properly making the time schedule of our work. Cost of reduction is achieved by selection of more efficient material or by an improved design.
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Flat roofs on which water may accumulate may require analysis to ensure that they are stable under ponding conditions. A flat roof may be considered stable and an analysis does not need to be made if both of the following two equations are satisfied:

C _p + 0.9 C _s £ 0.25

I _d ³ 25S ⁴ / 10 ⁶

Where C _p = 32 L _s L ⁴ _p / 10 ⁷ I _p

C _s = 32 SL ⁴ _s / 10 ⁷ _s

_{L p = length, ft (m), of primary member or girder}

_{L s = length, ft (m), of secondary member or purlin}

_{S = spacing, ft (m), of secondary members}

_{I p = moment of inertia of primary member, in ⁴}

_{(mm ⁴ )}

_{I s = moment of inertia of secondary member, in ⁴}

_{(mm ⁴ )}

_{I d = moment of inertia of steel deck supported on secondary members, in ⁴ /ft (mm ⁴ /m)}

_{For trusses and other open-web members, I s should be decreased 15 percent. The total bending stress due to dead loads, gravity live loads, and ponding should not exceed 0.80F y , where F y is the minimum specified yield stress for the steel.}

The total number of connectors to resist V _h is computed from V _h / q, where q is the allowable shear for one connector, kip (kN). Values of q for connectors in buildings are given in structural design guides.

The required number of shear connectors may be spaced uniformly between the sections of maximum and zero moment. Shear connectors should have at least 1 in (25.4 mm) of concrete cover in all directions; and unless studs are located directly over the web, stud diameters may not exceed 2.5 times the beam-flange thickness.

With heavy concentrated loads, the uniform spacing of shear connectors may not be sufficient between a concentrated load and the nearest point of zero moment. The number of shear connectors in this region should be at least

N ₂ = N ₁ [ ( M b / M _{m a x} ) - 1] / ( b – 1 )

where M = moment at concentrated load, ft kip (kN-m)

M _max = maximum moment in span, ft kip (kN-m)

N ₁ = number of shear connectors required between M _{m a x} and zero moment

b = S _{t r} / S _s or S _{e f f} / S _s , as applicable

S _{e f f} = effective section modulus for partial composite action, in ³ (mm ³ )

Shear on Connectors

The total horizontal shear to be resisted by the shear connectors in building construction is taken as the smaller of the values given by the following two equations:

V _h = 0.85 f ^‘ _c A _c / 2

V _h = A _s F _y / 2

where V _h = total horizontal shear, kip (kN), between maximum positive moment and each end of steel beams (or between point of maximum positive moment and point of contraflexure in continuous beam)

f ^‘ _c = specified compressive strength of concrete at 28 days, ksi (MPa)

A _c = actual area of effective concrete flange, in ² (mm ² )

A _s = area of steel beam, in ² (mm ² )

In continuous composite construction, longitudinal reinforcing steel may be considered to act compositely with the steel beam in negative-moment regions. In this case, the total horizontal shear, kip (kN), between an interior support and each adjacent point of contraflexure should be taken as

V _h = A _{s r} F _{y r} / 2

where A _{s r} = area of longitudinal reinforcement at support within effective area, in ² (mm ² ); and F _{y r} = specified minimum yield stress of longitudinal reinforcement, ksi (MPa).

In composite construction, steel beams and a concrete slab are connected so that they act together to resist the load on the beam. The slab, in effect, serves as a cover plate. As a result, a lighter steel section may be used.

Construction In Buildings

There are two basic methods of composite construction.

Method 1. The steel beam is entirely encased in the concrete. Composite action in this case depends on the steel-concrete bond alone. Because the beam is completely braced laterally, the allowable stress in the flanges is 0.66F _y , where F _y is the yield strength, ksi (MPa), of the steel. Assuming the steel to carry the full dead load and the composite section to carry the live load, the maximum unit stress, ksi (MPa), in the steel is

F _s = ( M _D / S _S ) + ( M _L / S _{t r} ) ? 0.66F _y

where M _D = dead-load moment, in-kip (kN-mm)

M _L = live-load moment, in-kip (kN-mm)

S _s = section modulus of steel beam, in ³ (mm ³ )

S _{t r} = section modulus of transformed composite section, in ³ (mm ³ )

An alternative, shortcut method is permitted by the AISC specification. It assumes that the steel beam carries both live and dead loads and compensates for this by permitting

a higher stress in the steel:

f _s = M _D + M _L / S _s ? 0.76 F _y

Method 2. The steel beam is connected to the concrete slab by shear connectors. Design is based on ultimate load and is independent of the use of temporary shores to support the steel until the concrete hardens. The maximum stress in the bottom flange is

F _s = M _D + M _L / S _{t r} £ 0.66 F _y

To obtain the transformed composite section, treat the concrete above the neutral axis as an equivalent steel area by dividing the concrete area by n, the ratio of modulus of elasticity of steel to that of the concrete. In determination of the transformed section, only a portion of the concrete slab over the beam may be considered effective in resisting compressive flexural stresses (positive-moment regions). The width of slab on either side of the beam centerline that may be considered effective should not exceed any of the following:

1. One-eighth of the beam span between centers of sup- ports

2. Half the distance to the centerline of the adjacent beam
3. The distance from beam centerline to edge of slab

The AISC specification for allowable stresses for buildings specifies allowable unit tension and shear stresses on the cross-sectional area on the unthreaded body area of bolts and threaded parts. (Generally, rivets should not be used in direct tension.) When wind or seismic load are combined with gravity loads, the allowable stresses may be increased one-third.

Most building construction is done with bearing-type connections. Allowable bearing stresses apply to both bearing-type and slip-critical connections. In buildings, the allowable bearing stress F _p , ksi (MPa), on projected area of fasteners is

F _p = 1.2 F

where F _­u is the tensile strength of the connected part, ksi (MPa). Distance measured in the line of force to the nearest edge of the connected part (end distance) should be at least 1.5d, where d is the fastener diameter. The center-to-center spacing of fasteners should be at least 3d.