ABSTRACT
Many tall buildings, deep underground railway tunnels and large halls are built in high-density cities (Chow, 2003a, 2005a, 2007; Tsujimoto, 2008). Structural elements are either concrete with steel reinforcement or steel framework with fire protection. There are new architectural features of green or sustainable buildings. Although combustible natural materials such as timber are not allowed as building materials in some cities such as Hong Kong, internal partitions used to be made of timber products (Buildings Department, 1995, 1996a, 1996b; Fire Services Department, 1998). Such timber partitions would cause fire problems as demonstrated before by fires in Karaoke venues (Chow et al 2008a). There are also many new materials made from plastic composites with fire-retardant systems (Wang and Chow, 2005). Such materials passing the fire tests specified in codes such as ease of ignition (British Standards, 1979) might not necessarily be safe in real fires under high radiation heat fluxes in post-flashover fires (Chow et al, 2003a). Radiative heat flux up to 440kWm–2 was measured in high-rack storage spaces (Wu, 2005). Several double-decker bus fires burning up all combustibles within 15 minutes, which occurred in Hong Kong (Chow, 2003b) and Shanghai (Beijing Times, 2005), are good examples that envelope materials with good thermal insulation are not safe in a fire. Buildings with thermal insulation might give new fire safety problems on having shorter time to flashover (Chow, in preparation). Large accidental fires have occurred in old high-rise buildings such as the big Garley Building fire (Chow, 1998), cross-harbour tunnels and buses in Hong Kong, and in many old high-rise buildings and new shopping malls in China (Chow, 2001, 2003b). Non-accidental fires reported over the world included the terrorist attack fires in the World Trade Centre on 11 September 2001 (WTC-911) in the US (Federal Emergency Management Agency, 2006); arson fires in universities in Beijing; and underground railway arson fires in South Korea and Russia. Several arson fires were reported in Hong Kong in a bank (Chow, 1995), a karaoke venue (Chow and Lui, 2001) and an underground train vehicle (Chow, 2004c). Fire safety is therefore a concern for buildings in high-density cities.
