Navigation:  Concrete Design > G-05 (Flexural Design of Cantilever Concrete Slab)

Objective

To verify the flexural design of the concrete slab

 

Problem Description

 

The 6 ft cantilever concrete slab shown below has a length of 30 ft and a thickness of 7.5 in.  It is subjected to a uniform load of 350 lb/ft^2.  Design the flexural reinforcement for the slab according to ACI 318-02 code.  The concrete cover (c.c.) is 1.0 inch.  Use fc = 4 ksi, fy = 60 ksi

E = 3644 ksi, v = 0.15

 

 

Finite Element Model

12 x 60 shell elements, each of which has a size of 0.5 x 0.5 ft.

Model type: 2D Plate Bending, Use Kirchhoff thin plate bending

 

Results

The maximum design moment (Wood-Armer moment) in top-X direction Top-Mux  = -6.381 kip-ft/ft.  The program gives the corresponding top-X direction steel Top-Asx = 0.2238 in2/ft, which is consistent with the following hand calculation.

in2/ft

The contour (rotated) of the top steel required in X-direction is shown below.

 

Comments

No minimum top or bottom reinforcement is considered in this example.  The Kirchhoff thin plate (instead of the MITC4 thick plate) formulation is used for analysis.  This is generally recommended for models that contain only rectangular elements of thin or moderately thick plates (shells).

 

Reference

None