1 / 26

Umm Al-Qura University Department of Civil & Structural Engineering

Design of reinforced concrete II Design of Flat Slab Floors Lecture (3). Umm Al-Qura University Department of Civil & Structural Engineering. Flat Slab Floors. A Flat slab floor is supported directly by columns without the use of beams.

casey-chase
Télécharger la présentation

Umm Al-Qura University Department of Civil & Structural Engineering

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Design of reinforced concrete II Design of Flat Slab Floors Lecture (3) Umm Al-Qura University Department of Civil & Structural Engineering

  2. Flat Slab Floors • A Flat slab floor is supported directly by columns • without the use of beams. • The slab may be with constant thickness or in the • area of the column it may thickened as a drop panel. • The column may also be constant section or it may • be flared to form a column head or capital, see • Fig 8.10 • The drop panels are effective in: • Reducing the shear stresses. • Provide an increased moment resistance.

  3. The flat slab advantages: • 1. Simplified formwork. • 2. Reduced storey heights make it more economical. • 3. Windows can extent up to the underside of the slab. • 4. No beams to obstruct light and air circulations. • 5. Absence of sharp corners gives greater fire resistance. • Deflection requirements will generally govern slab thickness • which should not be less than 180 mm for fire resistance.

  4. Interior panels of the flat slab should be divided as • shown in figure 8.11 into: Column strip Middle strip • Drop panels should be ignored if their smaller • dimension is less than one third of the smaller panel • dimension lx. • Moments are distributed between the strips as • shown in table 8.7.

  5. If the column strip is narrower because of drops, the • moment resisted by the column and middle strips should • be adjusted proportionally as illustrated in example 8.7.

  6. The reinforcement should be arranged according to • the rules illustrated in figure 8.2. • At least two bottom bars in each orthogonal direction • should pass through the internal columns to • enhance robustness. • EC2 requires that the design shear force be increased • above the calculated value as follows: • V eff = 1.15 VEd for internal columns with approximately • equal spans • = 1.4 V Ed for edge columns • = 1.5 VEdfor corner columns

  7. Punching Shear Reinforcement for Flat Slabs • The shear stress should be checked first with respect • to the maximum permissible shear force, VRd, max Where u = punching shear perimeter d = effective depth of tension reinforcement. VRd,max = Design value of maximum punching shear resistance.

  8. The reinforcement should be provided in at least two • perimeters of links. • The spacing of link perimeters (see the figure 5.10) • should not exceed 0.75d. • The spacing of link legs around a perimeter should • not exceed 1.5d within the basic control perimeter • (2d from the column face) . • And should not exceed 2d for perimeters outside • the basic control perimeter where that part of the • perimeter is assumed to contribute to the shear • capacity (see Figure 5.10).

More Related