Date post: | 06-May-2015 |
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WELCOME TO THE PRESENTATION ON FLAT PLATE (SLAB DESIGN)……
YEASIR MASUDID NO: 10.01.03.052
PRESTRESS CONCRETE DESIGN SESSIONAL
(CE-416)
FLATE PLATES:Flat Plates are concrete slabs which are carried directly by columns, without the use of beams or girders..
Uses :Commonly used where spans are not large (20 to 25 ft).
& also loads not particularly heavy (60 to 100 Psf)
What Is FLATE PLATES
DIFFERENCE BETWEEN TWO WAY & FLAT
PLATE TWO WAY SLAB: Slabs are resting on T-Beams.
Slab load transfer to the beams and then in to the columns.
FLAT PLATE SLAB :load is directly transferred to the columns
the shear is very critical at the area of connection of slab with column (called punching shear).
LITTLE CONFUSION REGARDING
FLAT PLATE & FLAT SLAB!!!!!!!!!!!!!
The flat plat is a slab of uniform thickness while in flat slab there is thickened slab region in the vicinity of the column that includes either drop panel or column capitals.
Figure: Drop Panel & Column Head
ENSURE THAT:
Reinforcement bars should be properly detailed between the columns and slabs.
Punching shear checks are critical & vertical shear reinforcement should be detailed accordingly.
Analysis (Moment Determination):
1. A method of frame analysis such as moment distribution, or stiffness method or a Computer.
2. A simplified method using the moment & shear co-efficient Table.
STEPS OF FLAT PLATE SLAB DESIGN STEPS OF FLAT PLATE SLAB DESIGN
DETERMINE THICKNESS
DEAD & LIVE LOAD CALCULATION
MOMENT CALCULATION BY USING TABLS & CO-EFFICIENTS
REINFORCEMENT DESIGN
SHEAR CHECK
Figure: Design Moment & Shears for flat plate floor interior Panel C. (a): Moments(b): Shears
Another Important Aspect regarding flat plate design is punching shear at the columns which require supplementary shear reinforcement, & transfer of unbalanced moments to the column which may require additional flexural bars in the negative bending region of the column strip
ADVANTAGES:
The simplified Formwork. Reducing the Story Height which makes it Economical. There are no beams to obstruct light & circulation of air. Less danger of concrete spalling & exposing reinforcement.
LIMITATIONS:
Loads due to higher thickness of plate elements as required to control deflection
Stiffness & weight consideration in earthquake areas