Robustness of structures in re
In structural design, prevention of disproportionate collapse under accidental loading or malicious actions is an increasingly important design requirement. Progressive collapse is the ultimate form of disproportionate collapse, and its occurrence in the World Trade Center buildings on September 11, 2001, brought home, in the most tragic way, the devastating consequences of re-induced progressive structural collapse. The prevention of disproportionate or progressive structural collapse is provided by structural robustness, which equates to the ability of a structure, or structural system, to accept a certain amount of damage without the structural failing to any great extent (Institution of Structural Engineers [ISE] 2010); it implies insensitivity to local failure. In Eurocode EN 1991-1-7 (Committee of European Normalization [CEN] 1991-2006), the formal de nition of robustness is “the ability of a structure to withstand events like re, explosions, impact or the consequences of human error without being damaged to an extent disproportionate to the original cause”. This chapter is concerned with robustness of structures in re. This is an active research topic, and there is still no de nitive methodology of providing means of achieving adequate robustness for structures in re. So, what this chapter intends is to de ne the context within which structural robustness in re is considered, to identify a number of scenarios that may initiate re-induced disproportionate collapse, and to provide a framework under which methods for achieving robust structural design for re may be developed. Joint (connection) behaviour in re is a critical issue affecting structural robustness in re. Chapter 8 provided a detailed commentary on joint behaviour in re. This chapter explains the implications of joint behaviour on structural robustness in re.