BAR BENDING SCHEDULE OF ONE WAY SLAB
Additionally of BENDING SCHEDULE OF ONE WAY SLAB ; A one way slab is a type of R CC slap that’s supported by two opposite sites and is designed to primarily resist bending in one direction. One way slab are rectangular in shape with a thickness that varies depending on the load requirements and span of the slab, one way slabs are different from two way slabs because they are supported by two opposite sides, only while two ways slabs are supported on all four sides. This means that one way slabs are designed to resist a bending in one direction. Action while two ways slabs are designed to resist bending in both directions, the aspect ratio that’s the ratio of longer span to the short span shall be greater than or equal to 2 for one way slabs, and if this ratio is less than two, then we can call it a two way slab
Before we prepare the bar bending schedule we must know about the various types of bars used in a one way slab The main bars in a one way slab are placed at the bottom of the slab to resist it to the tensile forces that arise due to bending these bars are placed parallel to the direction of the shorter span since the loads are carried along the short span only and the main bar anchored into the supports at either ends. If we talk about the distribution bars, these bars are provided to take care of the secondary stresses arising in the longer span due to the effect of bending besides this. They also take care of the temperatures stresses, creep stresses and the shrinkage stresses. One of the key functions of these bars is to hold the main bars in position while concreting apart from these bars, we provided top extra bars. In case the main reinforcement is provided as alternative bend up bars to take care of the negative bending moments at both ends too.
Furthermore Now Let’s Understand how to prepare the bar bending schedule of one way slab
Given Data :
Length (Clear Span) = 6 m (6000 mm)
Width (Clear Span) = 3m (3000mm).
Main Bar = 10 mm @260mm c/c.
Distribution Bar = 8 mm @ 290 mm c/c.
Clear cover = 20 mm (Top and Bottom)
Thickness = 140 mm
Development length = 48d
No of Main Bars =Longer span of Slab/Spacing+1
6000\260+1 = 24.07 (say 25 Bars)
Firstly to Calculation for Main Bars:
No of Main Bars = Longer span of Slab (Ly)/Spacing +1
= 6000\260 + 1 = 24.07 (say 25 Bars)
Cutting Length of Main Bar =Lx+2Ld+ (1 x Inclined length) – (45° bend x 2)
= 3000+ (2 x 48 x 10) + (1 x 0.42 x D) – (1d x 2)
(D = Slab thickness – 2 side clear cover – dia of bar 140-40-10 =90 mm)
= 3000+ (2 x 48 x 10) + (0.42 x 90)-(1 x 10 x 2) = 3978 mm or 3.98 m
Total length of main Bars = 3.98 x 25 = 99.45 m
Weight of main Bars = D²/162.2 x L
= 10²/162.2 x 99.45 = 61.31 KG
Secondly Calculation of DISTRIBUTION BARS
No of Distribution Bars = Shorter span of Slab (L) /Spacing +1
= 3000/290 + 1 = 11.3 (say 12 Bars)
Calculation for Distribution Bars:
No of Distribution Bars = Shorter span of Slab (L)/ Spacing +1
= 3000/290 + 1 = 11.3 (say 12 Bars)
Cutting Length of distribution Bar = Ly + 2Ld
= 6000+ (2 x 48 x 8) = 6768 mm or 6.768 m
Total length of distribution Bars = 6.768 x 12
= 81.216m
Weight of distribution Bars = D²/162.2 x L
= 8²/162.2 x 81.216 = 32.05 KG
Thirdly to Calculation for Top Distribution Bars:
Top bars are provided at top of critical length L/4 (Refer drawing)
No of Top Distribution Bars = ((Lx/4)/spacing + 1)x2
= ((3000/4)/290 + 1) x 2 = 7.17 (say 8 Bars)
Cutting Length of Top Distribution Bar = Cutting Length ofBottom Distribution bar = 6.768m
Total length of Top bars = 6.768 x 8 = 54.144 m
Weight of top bars = D²/162.2 XL
= 8²/162.2 x 54.144 = 21.36 KG
Calculation for Top Extra Bars:
No of Top Extra Bars = (ly/Spacing +1)x2
=(6000/520 + 1) x 2 = 25.1 (say 26 Bars)
Cutting Length = (Lx/4) + Ld
= (3000/4) + 48 x 8 = 1134 mm = 1.13m
Total length of Top Extra Bars = 1.13 x 26 = 29.4m
Weight of Top Extra Bars = D²/162.2 × L
= 8²/162.2 x 29.38 = 11.6 KG
Total weight of steel = 61.31+32.05 +21.36 + 11.6 = 126.3 KG
Adding 5% of wastage = 5% of 126.3 = 6.32 KG
Finally Total Weight of steel Required = 126.3 + 6.32 = 133 KG
