One-way slabs :
The transfer of loads from a slab to beams is controlled by the slab's geometrical dimension and the direction of reinforcements. The load of the slab, including self-weight, live load, and imposed dead load, are distributed over the beams on their sides
It transfers the imposed loads in one direction only. They may be supported on two opposite sides only, in which the structural action is essentially one-way, the loads being carried in a direction perpendicular to
the supporting beams or walls. But rectangular slabs often have such proportions and supports (e.g., relatively deep, stiff monolithic concrete beams) that result in two-way action [Fig. 1.1(b)]. At any point, such slabs are curved in both directions, resulting in biaxial bending moments. It is convenient to think of such slabs as consisting of two sets of parallel strips, in each direction and intersecting each other. So part of the load is carried by one set and the remainder by the other.
Different Load Calculation on Column, Beam, Wall & Slab
Column = Self Weight x Number of floors
Beams = Self Weight per running meter
Wall Load Per Running Meter
Total Load on Slab (Dead Load + Live Load +Wind Load + Self-Weight)
Besides this above loading, the columns are also subjected to bending moments that have to be considered in the final design. These tools are reduced laborious and consuming method of manual calculations for structural design, this is highly recommended nowadays in the field.
The most effective method for designing structure is to use advanced structural design software like STEAD Pro or ETAS. For professional structural design practice, there are some basic assumptions we use for structural loading calculations.
Let us calculate the total load over the beams B1 & B2 as shown below.
Given data:
Span of beam B1= 5500 mm. = 5.5 m.
Span of beam B2 = 2500 mm. = 2.5 m.
Sectional dimension of all the beams = 230 mm. x 450 mm. = 0.23 m. x 0.45 m.
Calculation:
LX /LY = 5500 mm. / 2500 mm.
= 2.2 > 2.
Therefore, it is a one-way slab.
The load distribution of one-way slab over the beams are as shown below.
1. Beam - B1:
Total load over the beam B1
= [Self wt. of the beam + superimposed load from the slab]
Here,
(a) Self wt. Of the beam /m.
= [(area of cross-section) × density of RCC]
= [(0.23 m. x 0.45 m.) × 25 KN/m³]
= 2.588 KN/m.
Total self-wt. Of the beam= [beam wt./m × span of the beam]= [2.588 KN/m × 5.5 m.]= 14.234 KN. Factored self-wt. Of the beam= [1.5 × 14.234]= 21.351 KN.
(b) Load transferred from slab to the beam B1
= [1/2 x (area of slab) x W]
Before proceeding further, Go through the article 👇
Understanding the concept of the load distribution from slab to beam.
Where all the load distribution formula is derived.
= [1/2 x (5.5 x 2.5) x 12.94]
The value of W is taken from the article
How to calculate the total load over the RCC slab?
= 88.96 KN.
Total factored load over the beam B1
= [Factored self wt. Of the beam + factored load from the slab]
= [21.351 + 88.96]
= 110.311 KN.
2. Beam - B2:
Total load over the beam B2
= [Self wt. Of the beam]
Here,
(a) Self wt. of the beam
= [(area of cross-section) × density of RCC]
= [(0.23 m. x 0.45 m.) × 25 KN/m³]
= 2.588 KN/m.
Factored self wt. of the beam
= [1.5 × 2.588 KN/m]
= 3.88 KN/m.
Total factored self-wt. Of the beam
= [factored wt./m × span of the beam]
= [3.88 KN/m × 2.5 m.]
= 9.70 KN.
Total factored load over the beam B2
= 9.70 KN.
Note: Beam-B2 does not carry any load from the slab.
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