10.01.03.049-One Way Slab
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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.
10.01.03.049-One Way Slab
- 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 11/25/2013 1
- 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 11/25/2013 2
- 3. DEFINITION OF SLAB Layer of reinforce-concrete with uniform/variable thickness supported by restraints Figure: 11/25/2013 3
- 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. 11/25/2013 4
- 5. PICTURE OF ONE WAY SLAB
- 6. PICTURE OF ONE WAY SLAB 11/25/2013 6
- 7. PICTURE OF ONE WAY SLAB 11/25/2013 7
- 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 11/25/2013 10
- 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) 11/25/2013 11
- 12. LOAD ASSIGNED OF SLAB 11/25/2013 12
- 13. LOAD ASSIGNED OF SLAB 11/25/2013 13
- 14. LOAD ASSIGNED OF SLAB 14
- 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″ 11/25/2013 15
- 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 11/25/2013 16
- 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. 11/25/2013 17