One way slab ACI Code (Concrete)

Download the design spread sheet here

Glimpse of the design spread sheer below.

Design Example:

Design an eight span floor slab considering 1 m wide strip. The corner beams are 400 mm wide and intermediate beams are 350 mm wide. The concrete strength is 25 MPa and the reinforcement strength is 400 MPa. The live load of slab is 4.7KPa.

Solution:

1.       Estimate the thickness of the floor

Min. h = L/24 for end bays = 4600 – (350/2) /24 = 184 mm

Min. h = L/28 for interior bays = 4600/28 = 164 mm

We provide a 190 mm clear depth, 20mm clear cover and assume 15mm reinforcement bars

2.       Factored loads

WDs = (0.190 x 1000 x 1000)m3 x 2450 kg/m3 x (9.81/1000) KN/kg = 4.57 KN/m2

Using ACI Appendix C (Select ACI section 9.2.1 or 9.3 or Appendix C accordingly)

U = 1.4 D + 1.7 L

 =1.4 x 4.57 + 1.7 x 4.7

= 15.02 KN/m2

---------------------------------- END ------------------------------------------------

Comparison of Bending Moment between Moment co-efficient and Beam Analysis

Below is the exercise where the Bending moment from Moment co-efficient of ACI code and Beam analysis program is compared.

Picture: 1 Continuous beam with Fixed ends

Picture: 2 Continuous beam with Pinned ends