Fire-induced thermal and structural behavior of steel arches: a finite element investigation

Resumo

Arches are efficient structural forms for spanning large distances, yet their nonlinear response becomes highly complex under fire conditions due to temperature-dependent degradation of steel properties. This study investigates the thermal and thermo-mechanical behavior of steel arches subjected to fire through finite element simulations performed in the SAFIR software. The adopted numerical models were validated against published experimental and numerical data. Parametric analyses were conducted to evaluate the influence of boundary conditions, rise-to-span ratio, load level, and fire exposure configuration on structural response. Results revealed that fixed supports significantly reduce mid-span displacements compared with pinned supports under identical fire scenarios. Increasing the rise-to-span ratio leads to larger deformations and lower global stiffness. Full cross-section exposure produced faster and greater displacements than partial (web-only) exposure. Variations in mechanical loading followed expected trends, confirming the consistency of the model. The study highlights the need to incorporate both thermal and geometric nonlinearities in predictive analyses and underscores that support conditions and geometric proportions are key parameters for reliable fire-resistance design of steel arches.