XGBoost Correction of Codified Flexural Resistance for Hybrid Double-I-Box Cold-Formed Steel Beams

Codified flexural-resistance equations give a clear mechanical estimate for cold-formed steel beams, but they do not represent the combined effect of hybrid steel grades and changing buckling behaviour uniformly. We compile 240 experimental and validated finite-element results for Hybrid Double-I-Box Beams (HDIBBs). This study retains the regime-specific code moment as the mechanical base and trains XGBoost only to predict the measured-to-code resistance ratio. The corrected resistance follows  using the section geometry, material strengths, hybrid ratio, slenderness, elastic critical moment and code resistance as pre-test inputs. The correction reduces the overall mean absolute percentage error from 13.71% for the code estimate to 2.30%. Regime-wise out-of-fold  values reach 0.932, 0.931 and 0.978 for local, distortional and lateral-torsional buckling tracks, respectively. The residual mean equals , which indicates low overall bias. The proposed correction improves resistance screening while retaining the codified calculation as the visible mechanical reference.