effective section modulus for single angle

[JokaSteel]

Hello,
Does anyone known how calculate the effective section modulus for an angle section ? I am using Eurocode, which is not clear in this matter...

I have an 3"x3"x5/16" Angle and SAP2000 gave me Wel,yy=0.707in^4 and Weff,yy=1.746in^4. Also, A=Aeff, i.e., the effective area it takes as the section area. Since that (normally) effective values are lower than geometric values, I am missing something.

Thanks a lot.

 

[johnbridge231]

Effective cross section properties are calculated according to Eurocodes, as follows:

i. For axial compression:
An effective cross section is formed which consists of some parts that are located near to edge or internal stiffeners and section edges. Aeff=The sum of the areas of these effective parts.

ii. For bending:
The neutral axis location is estimated assuming that the section is class 3!
Given above neutral axis location, one can draw a stress distribution (normal to NA) on the cross section.
The effective section in this case consists of:
a. The whole part under tension
b. The effective parts of the cross section under compression (these are formed in the same way as for axial compression)

Then, the properties of the section are calculated for the above parts i and ii.

Of course, effective cross section are less or equal to the geomtric values. In this case, SAP2000 may report this wrong..

Hope that has helped,

Regards.



Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html