PRINCIPLES OF STRUCTURES

Principles of Structures



Principles of Structures

Load experienced per square meter by the floor structure

Timber floor boards

40mm sand/cement screed

125mm reinforced concrete slab

timber floor boards = 0.15

screed = 0.6 x 40/25 = 0.96

concrete slab = 0.125 x 24= 3.00

dead load /m2 = 4.11kN/m



Maximum bending moment for a 1m wide strip of floor structure (spanning between beams)

Floor construction = 4.11kN/m2

Perimeter wall construction = 4.77kN/m2

self weight of beams = 0.6 kN/m

safety factors are 1.4 for dead load and 1.6 for live load to find design load

design load kN/m2

floor 1.4 x 4.11 5.75

wall 1.4 x 4.77 6.68

beams 1.4 x 0.6 0.84

imposed 1.6 x 2.5 4.00

total design floor load = 5.75 + 4.00 = 9.75kN/m2

Main reinforcement which is based on the maximum bending moment shall not be less than 0.15 per cent of the gross sectional area. The pitch of the main bars shall not exceed the following:

Three times the effective depth of slab, and

45 cm.

Bending moment due to dead load and live load may be taken as follows (IS: 456 - 2000)

 

At middle of end span

Over support

At middle of interior support

Over interior support

BM due to dead load

Bending moment due to live load

Total load per linear meter on the beam A-B

Beam A (8m span)

supports a total width of 6m

load from floor = 9.75 x 6 = 58.50kN/m

self weight of beam = 0.84 kN/m

design UDL = 59.34 kN/m

symmetry indicates reactions will be equal

reaction = (59.34 x 8) / 2 = 237.4 kN

Beam B

Load from floor = 3 x 9.75 = 29.25 kN/m

load from wall = 6.68kN/m

self weight of beam = 0.86kN/m

total design UDL = 36.79kN/m

symmetry indicates reactions will be equal

reaction = (36.9 x 8) /2 = 147.6kN

Reaction at the support to the beam at A

Load from floor = 3 x 9.75 = 29.25 kN/m

load from wall = 6.68kN/m

self weight of beam = 0.86kN/m

total design ...