IOP Conference Series: Materials Science and Engineering > 2017 > 245 > 1-10
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Civil Engineering
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Disaster of an industrial hall caused by an explosion of wood dust and fire
This article scrutinises a disaster affecting an industrial hall built of prefabricated reinforced concrete. As a result of an explosion of technological equipment used in the woodworking process, the entire pretensioned prestressed concrete girder structure, as well as the roof slabs, was badly damaged. Additional damage was caused by the high temperature generated by the resultant fire, as well as rapid cooling due to fire-fighting activities. Increased air pressure and the ensuing shock wave caused extensive damage to the brick walls in the neighbouring technology rooms. The explosion caused deformations of a brick chimney located more than 100 m from the blast zone. Subsequent investigations showed that a lack of adhesion of the tension members in the contact zone with an incoherent concrete structure could have led to a complete destruction of the covering structure. In the degraded girders located directly above the explosion area, a gradual loss of the prestressing force was observed. To prevent spreading of the disaster, ad hoc operations to protect both the structure of the building and the remaining technological equipment were developed. The girders located directly in the explosion zone were temporarily propped up and prepared for immediate removal. The article also presents an account of the reconstruction of the damaged building. In place of the removed prestressed girders, a light cover supported on truss steel girders was designed. The investigations that followed confirmed that an immediate cause of the hall’s damage was destructive processes triggered by the self-ignition of a mixture of wood dust in the improperly ventilated wood processing machinery. The resultant flame brought about a secondary explosion of the dust accumulated in the hall. The lack of proper human supervision of the industry control systems additionally increased the extent of the damage and financial losses. -
Local buckling behavior of welded stub columns with normal and high strength steels
High strength steels (HSSs) are increasingly applied in structural engineering due to their benefits in terms of mechanical performance and economy. Compared with normal strength steel (NSS) axial compression members, HSS members possess more critical local buckling behavior since its component plates may be designed as being more slender, and different mechanical properties of HSS, in terms of increased yield strength and reduced ductility, may result in different local buckling behaviors. In this paper, finite element (FE) analysis is performed to investigate the local buckling behavior of welded box section and I-section stub columns under axial compression with both NSS and HSS being incorporated, where initial geometric imperfections and welding-induced residual stresses are accurately simulated. Through this work, variation rules of post-buckling ultimate stress and local buckling stress of the axial compression members with steel yield strength and width-to-thickness ratio are clarified. By comparing the FE analysis results and existing test results with the corresponding design methods in ANSI/AISC 360-10, Eurocode 3 and GB 50017-2003, it is confirmed that the design methods for the local buckling behavior of welded box section and I-section stub columns under axial compression need to be modified. New design formulas are proposed to take the influence of the steel strength into consideration. -
C. Couto, P. Vila Real, N. Lopes, B. Zhao, Numerical investigation of the lateral torsional buckling of beams with slender cross sections for the case of fire, Eng. Struc. 106 (2016) 410-421.