# Homework Help: Neglecting axial deformation is slope deflection method

1. Aug 6, 2012

Hello,

When we use slope deflection method in frames we neglect axial deformation in order to get the same delta when the frame is sway,(that what i understood)

So i have two questions
1. Neglecting axial deformation means ignoring axial force??Or what??
2. How to neglect axial deformation in frame matrix like picture?if we use ,matrix not slope deflection

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2. Aug 7, 2012

### pongo38

A general assumption made in most structural analyses is that there is no significant change of geometry from before loading to after loading. In many situations, if flexural displacements are small, then axial displacements can be regarded as vanishingly small. Exceptions that come to mind include triangulated frames with loads at the nodes only, and cable-supported structures where cable extension can be significant. It could be instructive for you to use your matrix with all the 'AE/L' terms included, and compare the result with when they are all excluded.

3. Aug 7, 2012

Thank you very much brother.
I understand what you said
but regarding to first question. does Neglecting axial deformation means ignoring axial force??Or what??
and you say if i exlcuded EA/L from the above matrix, i should get result as slope deflection for the same problem.right

4. Aug 9, 2012