Two Way Slabs

All the concepts of Two Way Slabs

1. PREPARED BY: Asst. Prof. GAURANG PRAJAPATI CIVIL DEPARTMENT TWO WAY SLABS Mahatma Gandhi Institute Of Technical Education & Research Centre, Navsari (396450) ELEMENTARY STRUCTURAL DESIGN 6 TH SEMESTER CIVIL ENGINEERING

2. INTRODUCTION ESD 2160607 2 TWO WAY SLABS TWO WAY SLAB If the slab is supported on all four edges and if < 2, → Two way slab. The tendency of slab is to bend in both directions. Such slabs are called Two way slabs .  

3. INTRODUCTION ESD 2160607 3 TWO WAY SLABS In two way slabs, Main reinforcement is provided along (Short span) as well as (long span ). In case of two way slabs, Deflection and bending is less as compared to one way slabs. Therefore, B.M. is also reduced  

4. TYPES OF SLABS BASED ON SUPPORT CONDITIONS: ESD 2160607 4 TWO WAY SLABS According to support conditions, there are two types of two way slabs : Simply supported slab Restrained slab

5. TWO WAY SIMPLY SUPPORTED SLAB: (CORNERS ARE NOT HELD DOWN) ESD 2160607 5 TWO WAY SLABS In simply supported two way slab, when slab is loaded, corners are lifted up. At corners, as torsion is not produced. Therefore, torsion reinforcement is not provided . For the design, 1 m wide strip of slab is considered in both the directions. This strip is designed as a beam. M x = M y = IS 456 Clause No.: D - 2 Page No.: 90 IS 456 Clause No.: D - 2 Page No.: 90

6. RESTRAINED TWO WAY SLAB: (CORNERS ARE HELD DOWN) ESD 2160607 6 TWO WAY SLABS In case of Restrained Two way slabs, the edges of slab are restrained to the beams. When such slabs are loaded, corners are not lifted up, producing torsion at each corner. Thus torsion reinforcement is provided at each corner.

7. TYPES OF SLABS BASED ON SUPPORT CONDITIONS: ESD 2160607 7 TWO WAY SLABS No. Simply supported slab Restrained slab 1 Corners are not held down. Corners are held down. 2 When slab is loaded, corners are lifted up. When slab is loaded, corners are not lifting up. 3 At corners, torsion is not produced. Therefore, torsion reinforcement is not required. At corners, torsion Is produced. Therefore, torsion reinforcement is provided at each corners. 4 Edge strips are not provided. Edge strips are provided. 5 Design the slab as per IS ; 456, Clause No. D-2, Page No. 90. Design the slab as per IS ; 456, Clause No. D-1, Page No. 90.

8. CONTINUOUS SLAB (OVER ALL FOUR EDGES): ESD 2160607 8 TWO WAY SLABS When slab is continuous over all four sides, Reinforcement is provided along middle strip and over continuous edges. Torsion reinforcement is not provided in this kind of slab at corners.

9. REINFORCEMENT OF TWO WAY SLABS: ESD 2160607 9 TWO WAY SLABS