This document presents information on the design of one-way slabs. It defines one-way slabs as having a ratio of longer to shorter side of at least 2.0 and experiencing load distribution in the direction perpendicular to supports. The minimum thickness is specified in the ACI code based on span length and support conditions. Loads assigned include dead and live loads. Temperature and shrinkage reinforcement is also required perpendicular to main reinforcement to control cracking. The design procedure involves calculating minimum thickness, factored loads, moments, steel ratios, required depth and detailing of reinforcement.

1. SLAB DESIGN - ONE WAY
CE- 416
Pre-stressed Concrete Lab Sessional
Presented By:
Md. Abu Raihan
Id No:10.01.03.049
Course teachers:
Munshi Galib Muktadir
Sabreena Nasrin
Department Of Civil Engineering
Ahsanullah University of Science & Technology
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2. PRESENTATION OUTLINE
 Definition Of Slab
 Definition Of One-Way Slab
 Deflection
 Design Concept
 Minimum Thickness Of One-Way Slab
 Load Assigned To Slabs
 Temperature And Shrinkage Reinforcement
 Temperature And Shrinkage Reinforcement Ratio
 Design Procedure
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3. DEFINITION OF SLAB
Layer of reinforce-concrete with uniform/variable
thickness supported by restraints
 Figure:
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4. DEFINITION OF ONE WAY SLAB
 The ratio of the longer to the shorter side (L/B) of the slab
is at least equal to 2.0
 Support conditions is an important impact.
 Deflection is another important factor
 Load is distributed to the direction perpendicular of the
supporting restraints.
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5. PICTURE OF ONE WAY SLAB

6. PICTURE OF ONE WAY SLAB
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7. PICTURE OF ONE WAY SLAB
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8. DEFLECTION
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9. DEFLECTION
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10. DESIGN CONCEPT
 For the purpose of analysis and design, a unit strip of a
slab is cut out at right to the supported beams.
 The method here is used for rectangular beams.
 Figure
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11. MINIMUM THICKNESS OF SLAB
 To control deflection, ACI Code 9.5.2.1 specifies
minimum thickness values for one-way solid slabs,
shown in Table.
Element
Simply
Supported
One-End
Continuous
Both-End
Continuous
Cantilever
One-way
Slab
L/20
L/24
L/28
L/10
L is the span length direction of bending.
If Wc ≈ 90 – 120 psf factor will be applied by ( 1.65-0.005Wc)
If Fy ≠ 60 ksi factor will be ( 0.4 + Fy/100000)
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12. LOAD ASSIGNED OF SLAB
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13. LOAD ASSIGNED OF SLAB
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14. LOAD ASSIGNED OF SLAB
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15. TEMPERATURE AND
SHRINKAGE REINFORCEMENT
 Concrete gets shrinks and results cracking
 Cracks known as Hairline cracks.
 provide special reinforcement for shrinkage and
temperature contraction in the direction perpendicular to
the main reinforcement.
 Maximum lateral spacing 5h or 8″
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16. TEMPERATURE AND SHRINKAGE
REINFORCEMENT RATIO
Based on the Gross Concrete Area
Slabs with 40 or 50 grade reinforcement-0.002
Slabs with 60 grade reinforcement-0.0018
 Slabs where reinforcement with yield stress exceeding 60 KSI
at 35% yield-(0.0018*60000)/Fy
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17. DESIGN PROCEDURE
Step-1: From given panel find out the Tmin.
Step-2: Find out the Factored Load.(Wu = 1.2*DL + 1.6*LL)
Step-3: Find out Moments of the panel.
(M = Moment Coefficients*Wu*L²)
Step-4: Find out maximum steel ratio
(ρmax = 0.85*β1*(f´c/fy)*(εu/ εu + 0.004)
Step-5: Find dreq. (
)
Step-6: As and a. (
)
Step-7: Temperature and shrinkage reinforcement
Step-7: Reinforcement Detailing.
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18. REINFORCEMENT DETAILING
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19. REINFORCEMENT DETAILING
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20. THANK YOU
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