Upcoming SlideShare
×

Like this presentation? Why not share!

# Two way slab

## on May 07, 2009

• 29,783 views

### Views

Total Views
29,783
Views on SlideShare
29,537
Embed Views
246

Likes
2
603
3

### 3 Embeds246

 http://www.ustudy.in 218 http://www.slideshare.net 25 http://ustudy.in 3

### Categories

Uploaded via as Microsoft PowerPoint

### Report content

• Comment goes here.
Are you sure you want to
Your message goes here
• thak
Are you sure you want to
Your message goes here
• very interisting
Are you sure you want to
Your message goes here
• thanks
Are you sure you want to
Your message goes here

## Two way slabPresentation Transcript

• Direct Method   Reinforcement in Two-way Slabs  Footing Classification  Footing Design
• The reinforcement is for slabs without beams.
• Look at Example 13-7 Design of a flat plate floor without spandrel beams - Direct Design Method Look at Example 13-9 Design of a Two-way slab with beams in both directions. View slide
• Shear failure occurs when inclined cracks form due to flexural and shearing stresses. Two types of shear failure mechanism in 2-way slabs. (a) One-way shear (b) Two-way shear (Punching shear). View slide
• One-way shear Two-way shear
• Inclined cracking Slab slides down column Top (negative reinforcement pulls out of slab leaving no connection to the column Inclined cracking
• Critical perimeter is located d / 2 from column face, where d = effective depth of slab
• Critical perimeter is located d / 2 from column face, where d = effective depth of slab Slabs with Drop Panels
• Two-way Shear with Negligible Moment Transfer ACI Eqn. 11-1 Vu Vn where, Vu =Factored shear force (tributary area bounded by lines of zero shear) Vn = Nominal shear resistance of slab 0.85
• Two-way Shear with Negligible Moment Transfer Vn Vc Vs where, Vc =Shear resistance of concrete Vs = Shear resistance of steel (in most slabs, Vs = 0)
• (a) Two-way Shear with Negligible Moment Transfer For two-way shear in slabs (& footings) Vc is smallest of 4 ACI 11-35 Vc 2 f c b0 d c where, = long side/short side of c column concentrated load or reaction area b0 = length of critical perimeter around the column
• (b) Two-way Shear with Negligible Moment Transfer d s ACI 11-36 Vc 2 f c b0 d b0 where, = 40 for interior columns s 30 for edge columns 20 for corner columns
• (c) Two-way Shear with Negligible Moment Transfer ACI 11-37 Vc 4 f c b0 d Take smaller of (a), (b) and (c)
• Tributary area for Vu calculations Figure 13-41 MacGregor
• If V Vn can be increased by: , Vc u (1) Increase slab thickness (2) Use drop panel (3) Increase b0 by increasing column size or adding a fillet or capital (4) Add shear reinforcement