B-1.1 Analysis

For a frame, comprising members of compact section with full lateral restraint, an advanced structural analysis may be carried out, provided the analysis can be shown to accurately model the actual behaviour of that class of frames. The analysis shall take into account the relevant material properties, residual stresses, geometrical imperfections, reduction in stiffness due to axial compression, second-order effects, section strength and ductility, erection procedures and interaction with the foundations.

Advanced structural analysis for earthquake loads shall take into account, as appropriate the response history, torsional response, pounding against adjacent structures, and strain rate effects.

B-1.2 Design

For the strength limit state, it shall be sufficient to satisfy the section capacity requirements of Section 8 for the members subjected to bending, of Section 7 for axial members, of Section 9 for combined forces and of Section 10 for connections. Effect of moment magnification given in Section 9, instability given in Section 7 and lateral buckling given in Section 8 need not be considered while designing the member, since advanced analysis methods directly consider these.

An advanced structural analysis for earthquake loads shall recognize that the design basis earthquake loads calculated in accordance with IS 1893 is assumed to correspond to the load at which the first significant plastic hinge forms in the structure.