Cutting Length for Diamond Stirrups:
- Considered the Column size 400mm x 400mm.
- Adopting Dia of Bar used for stirrups is d = 8mm.
- Deducting the concrete cover 25mm from all sides. x = 400-20-20 = 360mm.
- The total length of stirrup = 4 x H =4 x 254 = 1016mm.
- Total Length of the hook:
- Total length of Bends:
Effective span of slab shall be lesser of the two. L = clear span + d (effective depth) L = Center to center distance between the support.
The term stirrups is usually applied to lateral reinforcement in flexural members and the term ties to lateral reinforcement in vertical compression members. U-shaped stirrups are placed in the tension side of concrete beams in which shear cracks would occur.
The 'U' or 'box' shaped reinforcement which is perpendicular to the main reinforcement in a beam is termed as STIRRUP. The reinforcement which is perpendicular to the main reinforcement in a column is termed as TIE. The purpose of ties and stirrups is different. Stirrups may be open at one end, usually the top.
Details Obtained from the Drawing
- Length of Footing = X = 2m.
- Breadth of Footing = Y = 1.6m.
- Height of the footing (Thickness) = h =0.3m.
- Diameter of the Main reinforcement bars = dm= 12mm.
- Diameter of Distribution Reinforcement Bars = dd =12mm.
- Spacing of Main reinforcement bars = sm = 150mm c/c.
For high rise buildings beyond 15 mtrs, the distance should not be less than the 1/3rd of the height of the building. For e.g.: if the height of building is 18 mtrs, then the distance shall be not less than 6 mtrs. If the hr is 24 mtrs, the distance shall be not less than 8 mtrs and so on.
There is no limit for distance between columns. If distance is more beam depth will be greater. Generally for residential building 4.5 metre to 6 metre is economical.
HOW TO CALCULATE RCC COLUMN SIZE
- Factored load on the column.
- The grade of steel, and.
- The grade of concrete. After which you can put the value of parameters in the factored load formula. This formula is used for calculating the size of the square, rectangular and circular column. The minimum size of the column should not be less than 230 mm x 230 mm.
Basics of Reinforced Concrete
Slab Design. 1. Effective
Span of
Slab.
2. Thickness of Slab.
| Type of slab | Ratio of span to depth |
|---|
| Simply supported and spanning in one direction | 30 |
| Continuous and spanning in one direction | 35 |
| Simply supported and spanning in two directions | 35 |
| Continuous and spanning in two directions | 40 |
1. Distance Between Main Buildings. A minimum distance of ten (10) feet shall be required between all main residential buildings established on the same lot or parcel of land. 2.
Longitudinal steels
- Compute total length of longitudinal bars which equal to the column height plus laps for footing multiply number of longitudinal bars.
- Convert that length into kilograms or Tons. This can be done by multiplying cross section area of steel by its total length by density of steel which 7850 kg/m3
It depends on span of your house slab. And without pillars means no open column , it has to be hide in wall. Generally 6–8 M span you can but more than that you have to make strong structure and spacial structure if you want. So,yes you can do without pillars show inside.
2.Beam Load Calculation:
- 230 mm x 450 mm excluding slab.
- Volume of Concrete = 0.23 x 0.60 x 1 =0.138m³
- Weight of Concrete = 0.138 x 2400 = 333 kg.
- Weight of Steel (2%) in Concrete = = 0.138 x 0.02 x 8000 = 22 kg.
- Total Weight of Column = 333 + 22 = 355 kg/m = 3.5 KN/m.
No, you do not need rebar for a 4-inch slab of concrete on grade. A 4-inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. Rebar is recommended on concrete measuring 5 – 6 inches thick.
Slab thickness requires a minimum clear distance of one-twelfth the distance between the ribs and not less than 2 inches.
Also, what size rebar would be used on a 4 slab? For driveways and patios a #3 rebar which is 3/8 inch in diameter should be sufficient for the purpose. If you are constructing walls, piers or columns I recommend the use of #4 (1/2 inch) rebar. For building footings I would use a #5 (5/8 inch) rebar.
Steel rods placed horizontally in concrete slabs for prevention of cracks due to temperature changes or drying; placed parallel to the reinforcing rods. The steel rods are placed at right angles to the main reinforcing bars.
- Suppose your calculated areaof steel is 6.54sqcm per meter and a spacing of 10mm rod at 120mm then if you want to change to 12mm rods,then spacing will be 170 mm.
- Procedure.
- You know the area of steel tobeprovidedsay Ainsqcm.
- You select the dia of rods and find out its area in sqcm say 'a' sqcm.
- Spacing =.
- EgA=6.54 sqcm.
Rebar should be placed evenly throughout the project. For a flat slab, such as a driveway, consider placing the rebar in an 18 inch grid spacing, keeping the edge rebar at the same distance from each side. For a patio you can use a grid spacing of 24 inches.
(1) Steel requirement for an R.C.C Foundation = 56 to 89kg for one Cum of Concrete . (2) Steel requirement for an R.C.C Pillar/ Column = 115kg to 144kg for one Cum of Concrete . Cross section area of steel in an R.C.C Pillar should be within 0.8% to 6% of the Cross Section area of a Pillar .
Slabs in the building are constructed using steel bars having a diameter of 8mm, 10mm, 12mm. In the same way Beams and columns of the building are constructed using 12mm to 25mm diameter of steel bars.
One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. The ratio of longer span (l) to shorter span (b) is equal or greater than 2, considered as One way slab because this slab will bend in one direction i.e in the direction along its shorter span.
In order to have properly anchored reinforcement, it is mandatory for rebars to be surrounded by concrete. The minimum spacing between two reinforcement bars should be at least equal to the maximum aggregate grain dimension with a margin of 5 mm.
Clear Cover for Slabs:The minimum cover thickness for slab reinforcement generally between 20 and 30 mm depending on the ecological circumstances present during the building's service life. The essential cover is maintained only with the help of a particular structure known as spacers.
The spacing of lateral ties should be 100 mm c/c through out the length of lapping. of vertical stirrups should be 8 mm diameter. The spacing should be 100 mm c/c at 1/3 span of beam at supports and 150 mm c/c at remaining mid span of beam.
Spacing. The distance between individual members or shingles in building construction.
Cutting Length of Stirrups
- Hook Length = 10d or 75 mm.
- 45° Bend = 1d.
- 90° Bend = 2d.
- 135° Bend = 3d.
The main purpose of stirrup is to hold the primary reinforcement bars. They also prevent columns and beams from buckling. The stirrups get placed diagonally when there is tension and compression caused by vertical and transverse tension.
One way of retrofitting the columns is by concrete jacketing. Concrete jacketing involves placing an additional layer of concrete covering the existing column, together with additional longitudinal bars and ties to enhance the flexural and/or shear capacities.
