By
Fawale, Babatunde Lawale
Ajayi, Johnson Oluwafemi
Oyedemi, Peter Oluwatosin

ABSTRACT
This project is an evaluation of the effectiveness of strawbale in building construction. It introduced the use of straw, which when baled could be used as a resource, that is, as a walling material, more economically than other conventional walling materials.

This study shows the edges that strawbale has over other conventional walling materials (sandcrete block), thermal insulating property, availability ease of construction, economical amongst others. The minimum plaster thickness (coating) which when applied to the strawbale wall that can give the optimum strength was found to be 15mm this is obtained from compressive strength test.

It also displays the graphical representation of the thermal insulation tests carried out on the two prototype buildings (strawbale and sandcrete block), in which strawbale building retained more heat than the sandcrete block building.
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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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Those flat roof which face a problem of water accumulation require stability analysis under ponding conditions. For checking the stability we need to see the following equations, if both of these are fulfilled

C_p+0.9C_s<= 0.25
I_d>=25S⁴/10⁶
Where
C _p= 32 L_s L⁴_p/10⁷I_p
C_s=32L_s⁴/10⁷I_s
L_p= Length of primarymember or girder in ft (m)
L_s= Length of secondary member or purlin ft (m)
S= Spacing of secondary members ft (m)
I_p= Moment of inertia of primary member in in⁴ mm⁴
I_s= Moment of inertia of secondary member in in⁴ mm⁴
I _d= Moment of inertia of steel deck supported on secondary members, in⁴/ft (mm⁴/m)

It should be noted that I_s should be decreased by 15% for trusses and other open-web members. Also the value of the total bending stress due to ponding , dead loads and live loads should not exceed 0.80F_y(the minimum specified yield stress for the steel)

We take the smaller value out of these two conditions to calculate the total horizontal shear which is to be to be resisted by the shear connectors in building construction
V_h= 0.85f^‘_cA_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 inch²(mm²)
A_s = Area of steel beam in inch²(mm²)

In continuous composite construction, the total horizontal shear, kip (kN), between an interior support and each adjacent point of contraflexure should calculated by

V_h = A_srF_yr/2

where
A_sr= Area of longitudinal reinforcement at support within effective area in ich²(mm² );
F_yr= Specified minimum yield stress of longitudinal reinforcement, ksi (MPa).

Total number of connectors required to resist V_h is given by V_h/q
where q is the allowable shear for one connector, kip (kN) and its value is given in structural design guides.

Some keypoints should be considered
1. Required number of shear connectors should be placed uniformly in the section having zero to maximum moment.
2. Shear Connectors should have a minimum of 25.4mm (1inch) of concrete cover in all the directions.
3) Stud diameter should not exceed 2.5 times the beam-flange thickness. ( May increase only if studs are located directly over the web)

In case of heavy concentrated loads, uniform spacing may not sufficient, so number of shear connectors are calculated as
N₂={N₁[MB/M_max-1]}/ (B-1)
where
M= Moment at concentrated load, ft-kip(kN-m)
M_max= Maximum moment in span ft-kip(kN-m)
N₁= Number of shear connectors required between M_maxand zero moment
B= S_tr/S_s or S_eff/S_s depending on condition.
S_eff= Effective section modulus for partial composite action in inch³(mm³)