If the concrete section has flanges and an excentric load is placed on that flange, hanging reinforcement needs to be calculated in order to avoid the flange shearing off.

The calculation model is defined as a strut-n-tie model according to the picture below.

flange 1.jpgflange 2.jpgflange 3.jpg

The calculation is carried out as an iterative process according to the following schema:

The goal is to find Fs which is the force that should be reinforced for.

Step 1: Make an educated guess for 'x'.

Step 2: Calculate z = h - t1 - t2 - x/2.

Step 3: Calculate Fs = Fc = (Fv * a) / z

Step 4: Calculate new x = Fc / fcc.

Step 5: Go to Step 2 while x has not significantly changed since last iteration, otherwise we have found Fs.

The distribution of the flange reinforcement is determined according to the right side pictures above.

B = 4 * h + b

For point loads the load width (b) is 0, for distributed loads b is equal to the distribution length.

See Viewing the design results for the how the flange reinforcement results are presented.

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PRE-Stress Documentation