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