Proper interpretation of sectional analysis results

Abstract

Displacement control algorithms commonly used to evaluate axial force-bending moment (PM) diagrams may lead to incorrect interpretations of the strength envelopes for asymmetric sections. This paper aims to offer valuable insights by comparing existing displacement control algorithms with a newly proposed force control algorithm. The main focus is on the PM diagrams of three example sections that exhibit varying degrees of asymmetry. The comparative study indicates that conventional displacement control algorithms inevitably introduce non-zero out-of-plane bending moments. The reported PM diagram in such cases erroneously neglects the out-of-plane moment and fails to represent the strength envelope accurately. This oversight results in significant and unconservative errors when verifying the strength of asymmetric sections.