## pipe shear stress

## pipe shear stress

(OP)

How is shear calculated on a circular pipe (column or beam)? I have one reference(Design Manual for Structural Tubing -1974) that says to use half the gross section - I am assuming gross area. This is shear across the member,not torsional shear. Why use half the gross section? Is there a shear stress distibution problem. maybe the pipe wall will bend before it pipe shears. Are ther any values for pvc pipe?

## RE: pipe shear stress

Note: applying the same technique to a wide flange beam results in fv= (V)/(area of web)(approximately).

I hope this helps.

## RE: pipe shear stress

In a round shape the effective shear area Av is 60% the gross area (Ag)...... Av=0.6 x Ag This is a geometric property and is independent of material ie steel, aluminum, pvc, etc

This is different then the rolling shear eqaution given by jec67. Effective shear area is also used to calculate shear deformations. The VQ/IT is correct equation for rolling shear and 2V/A is the derivation of VQ/It for rolling shear on a rectangular shape- I don't believe that this is correct for a round hollow section.

Good luck

## RE: pipe shear stress

For a circular section: fv = VQ/It

Q = (2r/pi)*(pi*r*t)

I = pi*r^3*t

t = 2* pipe wall thickness

Substituting these equations into VQ/It results in:

fv = 2V/A, where A = 2*pi*r*t (the xsectional area of the pipe).

For a rectangular section, using the same process:

fv = 1.5*V/A where A is the area of the rectangle

## RE: pipe shear stress

## RE: pipe shear stress

Good luck.

## RE: pipe shear stress

## RE: pipe shear stress

You may want to post a question under one of the mechanical forums, perhaps even the pressure vessel forum. Someone there may be able to give some advice as to what to use for a design value.

I hope this helps.

Please let us know what you come up with for a design value.

Regards

## RE: pipe shear stress