NIDA is an analysis and design software for nonlinear buckling analysis and design of steel structures, frames, trusses and buildings, light-weighted and slender skeletal structures, pretension structures and so on. It uses the curved stability function element as well as the refined finite element (PEP element) for buckling analysis which is unique among commercial programs. These two kinds of elements have the ability to take the member initial bowing into account at the element level, and hence one element per member is adequate for most practical structures.

In this approach, the sectional capacity and stress, allowing for the first-order and the second-order (P-Δ and P-δ) effects, are computed and directly compared with the design strength under factored loads.

Effective length or K-factor is to account for the P-Δ and P-δ effect which has already been considered automatically in NIDA and therefore the user needs not assume an effective length. 

Global structural geometrical change generates the P-Δ effect which is particularly important for sway frames. NIDA updates geometry, member curvature and initial force continuously and therefore user needs not classify frame type (i.e. sway or non-sway frame) or carry out frame stability check manually.

Copyright© 1996-2009 Professor SL Chan. Do not reproduce without permission.