PROKON GEEK SLAB DETAILING 101
GETTING PRIVY WITH SLAB DETAILING IN SHORT AND CONCISE LESSONS
PART ONE GETTING STARTED
WHAT IS A SLAB?
GENERAL NOTES CONTINUED
SHAPE CODES USED (SANS & BS)
01. SPACING OF REBARS (SOLID SLABS)
STRUCTURAL MEMBERS CONSTRUCTED TO PROVIDE
01. BENDING MOMENT OCCURRING AT MID SPAN
BAR SPACING
FLAT HORIZONTALPLANES IN
SANS 10144 IS MORE STRAIGHT FORWARD
BUILDING FLOORS, ROOFS, BRIDGES E.T.C
SHAPE CODE 20
MINIMUM ALLOWABLE PITCH IS 75mm
TYPES OF SLABS
AND 100mm FOR LAPS (where two bars join)
4000
6Y12-A-75 B1
4000
4000
4000
BUT AS A RULE OF THUMB
Ly
PROKON GEEK SAYS MAKE IT 100mm
10000
Supported on Walls or A System of Beams and Columns
MIN BAR SPACING IS 75 BUT
MAKE IT 100
WHY? VIBRATORS/POKERS
Simply Supported and Restrained
CODE 20
950
4000
01. CONVENTIONAL SLAB
Supports on the two opposite sides OR
Longer Side is => 2 the length of the Shorter Side
MAXIMUM SPACING IS A DIFFERENT BALL GAME ALTOGETHER
Lx
2500
a) One-Way Slab
600
800
600
800
950
CODE 20
Bending Occurs in One Direction
IT DEPENDS ON THE DEPTH OF THE SLAB
b) Two-Way Slab
ONE WAY SLAB
Longer Side is < 2 the length of the Shorter Side
FOR SLABS 200mm OR LESS
Bending Occurs in Two Directions
CODE 37
FOR EXAMPLE
x
4000
Ly
4000
Supports on all 4 edges OR
350mm MAX
CODE 37
800
800
CODE 20 SPLICE IF NECESSARY
400
400
CODE 20
02. FLAT SLABS
10mm Bars
bar diameter
600
spacing (x) = (2d)+(Bar Diameter)
IF YOU THINK I AM LYING CALCULATE :)
No Beams, Suitable were you need plain ceilings
1200
Minimum 200mm
1200
Plane Slab without drop and column without column head
FOR SLABS MORE THAN 200mm
With drop and column without column head.
CODE 43
1200
1200
600
ASSUMING NO LACERS
4000
spacing (x) = (2d)+(Bar Diameter)
TWO WAY SLAB
Supported directly by concrete columns
CODE 20
170
But could even go thicker
200
d
But 200mm to 400mm for Larger Loads
D
2500
Lx
Minimum or Average 100mm Thick or 4 Inches
600
600
600
CODE 20
600
LACERS
1200 600
1200
600
1200
1200
1200
600
600
1200
CODE 20
Without drop and column with column head.
well there is a table, just stick to it
03. HOLLOW RIBBED SLABS
600
4000
With drop and column with column head.
TABLE 14 - Maximum spacing of bars (450 MPa)
Slabs with Voids or Cores
and Save a lot of material
in slabs of thickness exceeding 200 mm
FLAT SLAB
Usually come precast then laid out
1
and jointed on site
2
3
4
5
6
7
02. CRACK CONTROL AND SHEAR CONTROL AT BOTTOM EDGES
mm
Position of
Slabs with Suare Grids visible from underneath
Reinforcement
Link in the description
CODE 38
CODE 42
(this is from SANS 10144)
Maximum spacing
04. WAFFLE SLAB
800
SHAPE CODE 37
Amount of tension reinforcement
%, gross
Up to 0.5
0.6
0.7
0.8
0.9
1.0
Span
350
300
250
250
200
175
Support
300
250
200
200
175
150
03. HOGGING MOMMENT AT TOP OF SUPPORTS
SHAPE CODE 20 OR SHAPE CODE 43
GENERAL NOTES
04. HOGGING MOMENT AND TORSION AND SHEAR CONTROL AT EXTERNAL SUPPORTS
THIS IS DIFFICULT TO GIVE AN ILLUSTRATED EXAMPLE ON
SOME IMPORTANT NOTES TO CONSIDER BEFORE WE GET STARTED
WITHOUT A REAL PROJECT
01.CONCRETE GRADE
Most peg it a grade 25 concrete i.e M25
COVER ILLUSTRATION
25
AND REMEMBER THIS IS FOR MAIN STEEL
25
25
But Should Normally Grade 35 or C 28/35
SHAPE CODE 38 OR SHAPE CODE 42
150
What does C28/35 Mean?
click on the link in the video description
ALSO IMPORTANT IS TO NOTE SPACING INCREMENTS
02.COVER
25
25
25
(BS 8110, Cl. 3.3, Cl. 4.12.3; BS8500, Tables A6, A10-14)
25 mm FOR INTERNAL SLABS
UP TO 200
75
100
125
150
175
200
AFTER 200
250
300
350
400
450
500
40 mm FOR external SLABS
CURTAILMENT OF STEEL
THIS IS JUST AVERAGE CHECK YOUR CODE FOR ACTUAL COVER
DEPENDS ON THE ACTUAL EXPOSURE CONDITIONS
WHY ITS IMPORTANT
1000
03.MIN AND MAX REINFORCEMENT
02. DIAMETER OF BARS USED IN A SLAB
OBVIOUSLY THE DESIGN WILL TELL YOU WHAT BARS YOU NEED TO USE BUT
565 mm2/m
This also applies where nominal reinforcement is placed.
2 x 565 mm2/m = 1130 mm2/m
14Y12-001-200 B2
Dia 32
14Y12-002-200 B2
FOR PRACTICALITY AND FROM EXPERIENCE
3000
3000
(14)
(14)
(14)
(14)
14Y12-001-200 B2
250
250
0.13% of bh i.e the cross-sectional area of the concrete
14Y12-005-200 T2
EXAMPLE
6Y12 @ 200mm C/C SPACING
AREA OF CONCRETE = 1000mm x 250mm =250 000mm2
TRY AND ENSURE IT DOES NOT EXCEED 15% OF YOUR SLAP THICKNESS
THUS PERCENTAGE OF REBAR = 1 135 / 250 000
PREFERRED MINIMUM DIAMTER IS 10mm
THE MAX BAR SIZE YOU SHOULD
USE FOR A 250mm THK SLAB
IS 32 mm
It is good practice to detail top and bottom bars separately
1000
and where any complication occurs, to include sections
<15% OF SLAB THICKNESS
11Y12-01 + 10Y12-01-250 B1 Alt
JUST DO
03
25
03
28Y12-003-200 B1
300
900
03. REBAR LAP LENGTHS
01
01
Y12-02-B2
01
250
01
01
PLEASE REFER TO WHATEVER CODE YOU USE BUT WITH SANS 10144
300
2700
300
2700
300
GO TO TABLE D-1: IT HAS EVERYTHING
SECTION 1-1
BUT AS A RULE OF THUMB
THIS IS HOW NON CURTAILERS WOULD HANDLE DETAILING
1
2
28Y12-006-200 T1
03
MULTIPLY DIAMETER OF SMALLEST BAR AT LAP WITH
1000
BUT PROBLEM IS
04
11Y10-03 + 10Y10-03-250 T1 Alt
04
GRADE OF CONCRETE
25
Y10-03-T1
250
04
04
SLAB DETAIL
SCALE 1:100
DIAMETER OF BAR
02
02
250
02
02
25
1. STEEL IS EXPENSIVE
04
200
NORMALLY
03
1
PEOPLE
03
300
SCALE 1:12.5
2
WHAT
7Y12-02 + 6Y12-02-250 B2 Alt
THIS IS
250
200
7Y10-04 + 6Y10-04-250 T2 Alt
Y10-04-T2
3000
ILLUSTRATIONS
02
10
12
16
20
25
TENSION LAP
MULTIPLY BY 50
COMPRESSION LAP
MULTIPLY BY 40
32
2. SOMETIMES YOU ONLY HAVE SHORT LENGTH BARS
40
3Y12s
ESP IN DEVELOPING COUNTRIES
Y12-01-B1
600
THIS IS WHAT ADVANCED DETAILERS NORMALLY DO
GRADE OF CONCRETE
SCALE 1:12.5
SO YOU WOULD PREFERABLY DO IT AS FOLLOWS
50
SECTION 2-2
30
3Y12s
DIAMETER OF BAR
BUT CODES RECOMMEND YOU DO THIS AS SHOWN BELOW
10
12
TENSION LAP
16
20
25
32
40
600
AND FRUGAL PEOPLE: TO SAVE PAPER
7Y12-00B + 7Y12-00A-200 B2 Alt
MULTIPLY BY 45
7Y12-00B + 7Y12-00A-200 B2 Alt
11Y10-03 + 10Y10-03-250 T1 Alt
COMPRESSION LAP
11R12-01 + 10R12-01-250 B1 Alt
MULTIPLY BY 35
GRADE OF CONCRETE
7Y12-02 + 6Y12-02-250 B2 Alt
14Y12-00D-200 T2
3Y16s
35
7Y10-04 + 6Y10-04-250 T2 Alt
(14)
(14)
(7+7)
(7+7)
(14)
(14)
(14)
(14)
DIAMETER OF BAR
10
12
16
20
25
TENSION LAP
MULTIPLY BY 40
COMPRESSION LAP
MULTIPLY BY 30
32
28Y12-00D-200 T1
40
SLAB REBAR TOP
14Y12-00C + 14Y12-00C-200 B1 Alt
28Y10-00G-200 T1
28Y12-00D-200 T1
SCALE 1:100
SCALE 1:100
03. NOTATIONS
BUT THIS IS WHAT I RECOMMEND WHEN LEARNING
11R12-01 + 10R12-01-250 B1 Alt
11Y10-03 + 10Y10-03-250 T1 Alt
7Y12-02 + 6Y12-02-250 B2 Alt
T1
B2
T2
7Y10-04 + 6Y10-04-250 T2 Alt
7Y12-00E + 7Y12-00E-200 T2 Alt
B1
14Y12-00D-200 T2
COLUMN EXAMPLE
IN THIS CASE YOU MAY NOT EVEN
NEED TO PROVIDE SECTIONS
SLAB REBAR BOTTOM
7Y10-00F + 7Y10-00F-200 T2 Alt
7Y10-03-250 T1
7
Y10
- 03
-
250
T1
NUMBER OF BARS
YOU WILL HAVE 7 BARS IN TOTAL
TYPE OF STEEL
HIGH YIELD STEEL (Y)
BAR MARK
IDENTIFIED AS 03 , LIKE AGENT 47
SPACING OF THE BARS
SPACING OF THE BARS
LAYER OF THE BARS
LAYER OF THE BARS
7Y10-03-250 T1
7Y10-00F + 7Y10-00F-200 T2 Alt
OKAY LETS TRY AND SIMPLIFY IT IN THE NEXT CHAPTER