1 Abstract This paper describes the non-linear mechanical response of a skylight shell structure, created using a glass envelope and structural steel members, in the event of an explosion. The system, currently under construction, has a geometrical axis of 52.50m (maximum) and 40.00m (minimum), and the span ratio n = 6.75 %. Several pressure wave signals were obtained, according to the American specifications of TM5-1300 [1], and the consequent non-linear time-history response of the system were investigated. Keywords: steel structures, non-linear analysis, blast response. 1 Introduction Following the collapses caused by explosions which have involved both civil and military buildings in recent years, the dimensioning of structures subjected to explosive forces and the verification of the resistance to collapse of one or more structural elements have become of utmost importance during the design phase. In the past, building design aimed at preserving the safety of people following an explosion only applied to buildings used for military purposes or those that were located near sites where explosives were stored or flammable materials were processed. However, in the current socio-political climate, particularly after the attacks on the Twin Towers and the Pentagon, the risk of building collapse is no longer considered remote for those buildings not necessarily used for military or strategic purposes. Attention is currently focused on branches of banks and other financial institutions, centers for political activity, religious sites and large commercial buildings. Therefore, with reference to the structural properties of a system as a general requisite for resistance to explosions, researchers in the last few years have concentrated on robustness, even though an explicit method for the evaluation of Paper 274 The Collapse of a Skylight Shell Structure caused by a Blast A. Angotzi 1 , A. Mussi 1 , E. Trolese 2 , M. Zanchin 2 R. Gori 3 and A. Mastropasqua 3 1 Arup Italy srl, Milan, Italy 2 Mastropasqua-Zanchin & Associates Structural Engineering Treviso-Udine, Italy 3 Department of Civil, Environmental and Architectural Engineering (DCEAE) Padua University, Italy ©Civil-Comp Press, 2012 Proceedings of the Eleventh International Conference on Computational Structures Technology, B.H.V. Topping, (Editor), Civil-Comp Press, Stirlingshire, Scotland