What are the two methods specified by the code for the design of two way slabs?
What are the two methods specified by the code for the design of two way slabs?
The one-way slab is deflected in a one-way direction and primary reinforcement is placed in one direction whereas the two-way slab deflects in two directions and primary reinforcement placement is in two directions. ACI 318-11 Code provides two methods for two-way slab design one of which is the direct design method.
How moments are calculated in two way slab?
The moments are calculated using the bending moment coefficients given by IS:456-2000. Based on the edge conditions, the coefficients vary. Once the coefficients are determined, the moments are calculated by the formula below, as per IS:456-2000, Annex D-1.1.
What are the types of two way slab?
There are mainly three types of designs for two-way slab.
- Two-way solid slab (with beams) Two-way Solid Slabs on Beams.
- Two-way Waffle Slab (with Beams) Two-way Waffle Slab (with Beams)
- Two-way Waffle Slab (with Integral Beams) Cast in Situ Two-way Waffle Slab with Integral Beams.
What is the minimum depth of two way slab?
Moreover, the minimum thickness of any two way slab without interior beams should not be less than the following: For slabs without drop panel 125 mm. For slabs with drop panel 100 mm.
How do you calculate reinforced concrete slab?
For the investigated conditions the reinforcement should be placed in the lower section of the slab: in this case the amount of reinforcement per 1 m3 of concrete will be 20 kg. When it is placed in the middle of the section its amount will be 30 kg/m3 of concrete, i.e., 1.5 times more.
What is difference between one way and two way slab?
The one-way slab is supported by a beam on two opposite side only. The two-way slab is supported by the beam on all four sides. In one-way slab, the load is carried in one direction perpendicular to the supporting beam. In two-way slab, the load is carried in both directions.
Where is two way slab used?
In two way slab, the ratio of longer span (l) to shorter span (b) is less than 2. In two way slabs, the load will be carried in both the directions. So, the main reinforcement is provided in both directions for two way slabs. Example: These types of slabs are used in constructing floors of a multi-storeyed building.
How do you identify a two way slab?
How do we calculate a one way or two-way slab? If L/b ratio is greater than or equal 2 or then it is considered a one-way slab. If L/b ratio is less than 2 then it is considered a two-way slab.
What is the minimum depth of slab?
minimum thickness should not be less than 4.75 inches not forgetting factor of safety. Standard concrete floor slab thickness is residential construction is 4 inches, five to six inches is recommended if the concrete will receive occasional heavy load, such as mortar homes or garbage trucks.
How is the coefficient method used in slab design?
Coefficient Method The coefficient method employs tables of moment coefficients for different slab edge conditions. The conditions are based on elastic analysis but inelastic redistribution is accounted for as well.
How to design two way slabs in concrete?
Design methods Simplified Design Methods Grashoff method Marcus method Egyptian Code method Direct Design Method”DDM” Equivalent Frame Method ” EFM ” Design Of Reinforced Concrete Structures ii Two-Way Slabs 3 4. Direct Design Method “D.D.M” Before discussion of this Method, we have to study some concepts: 1. Limitations: 1.
How are exact moments determined in two way slabs?
2 Analysis of Two-way Slabs by Coefficient Method The determination of exact moments in two-way slabs with various support conditions is mathematically formidable and not suited to design practice. Various simplified methods are therefore adopted for determining moments, shears and reactions in such slabs.
What are the limitations of two way slabs?
1. Limitations: 1. Three or more spans in each direction. 2. Variation in successive spans 33% ( 3. LL 2 DL 4. Column offset 10% in each direction. 5. L/B 2. 6. For slabs on beams, for one panel 2. Determination of Two way slab thickness: Case 1: interior and edge beams are exist. Where: