STRUCTURAL ANALYSIS OF A LONG SPAN
ROOF STRUCTURE AFTER A FIRE
Relazione a cura Ing. Mauro Madeddu (*), Ing. Sassi Samuele (*),
Prof. Ing. Setti Paolo (**), Ing. Marco Grigoletto (***)
(*) FSC Engineering S.r.l. - (**) Politecnico di Milano
(***) Maffeis Engineering S.p.A.

Abstract

After a fire took place in construction phase of a new elliptic roof of a shopping centre in Doha (Oasis Skylight - Mall of Qatar), which has a great span dimensions (112 x 68 m), a series of studies and analyses are performed to ensure the structural safety of the roof. The fire proofing previously applied on the roof structure limited the possible damage and the passive fire protection is renewed after the fire. The preliminary fire investigation is useful to understand the dynamics of the fire took place in the roof and the results are utilized to rebuild fluid dynamics models (two zones models by B-Risk software and CFD models by FDS software) in order to obtain thermal effects generated on structure. Assessment of post-fire damages of roof structure became possible by FEM analyses (Straus7 software) once the fluid dynamics models are performed. Welded connections and the highly loaded structural elements, which are critical, are investigated according to obtained results. In the end, the structural analyses are redone (Straus7 software) by taking into account the post fire effects (permanent deformations, etc.) and local reinforcements in order to guarantee structural safety with cost and time optimization.