Question

Which of the following is not an assumption of first order elastic analysis of rigid jointed frame?

(a) materials behave linearly

(b) yielding effects can be ignored

(c) member instability effects cannot be ignored

(d) frame instability effects can be ignored

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Question is taken from Methods and Assumptions of Analysis topic in section Structural Analysis, Loading and Load Combinations of Design of Steel Structures

Answer 1

Right answer is (c) member instability effects cannot be ignored

Easiest explanation: The following are the assumptions of first order elastic analysis of rigid jointed frame : (i) materials behave linearly, (ii) yielding effects can be ignored, (iii) member instability effects such as those caused by axial compression can ignored, (iv) frame behaves linearly frame instability effects such as those caused by moments due to horizontal frame deflection, etc can be ignored.