SLAB DESIGN - ONE WAY
Pre-stressed Concrete Lab Sessional
Md. Abu Raihan
Munshi Galib Muktadir
Department Of Civil Engineering
Ahsanullah University of Science & Technology
Definition Of Slab
Definition Of One-Way Slab
Minimum Thickness Of One-Way Slab
Load Assigned To Slabs
Temperature And Shrinkage Reinforcement
Temperature And Shrinkage Reinforcement Ratio
DEFINITION OF SLAB
Layer of reinforce-concrete with uniform/variable
thickness supported by restraints
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
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.
MINIMUM THICKNESS OF SLAB
To control deflection, ACI Code 22.214.171.124 specifies
minimum thickness values for one-way solid slabs,
shown in Table.
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)
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″
TEMPERATURE AND SHRINKAGE
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
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.