Towards the Design of Durable and High-Performance Tubular Structures

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Infrastructure is central to every aspect of life in Canada. Premature deterioration of infrastructure and repair of damage are multi-billion dollar problems. The proposed research program is motivated by an increasing number of reports on poor in-service performance and even hazardous collapse of galvanized steel structures across North America. Solutions will be developed to improve the structural performance and extend the service life of bridges, highway and parking structures, industrial plants and transmission towers composed of galvanized Hollow Structural Section (HSS) members and connections. The long-term goal is to facilitate design, fabrication, construction and maintenance of durable and high-performance infrastructure in Canada.*** The research will first address the contemporary issue of cracking of HSS components during hot-dip galvanizing, followed by a series of experimental and numerical investigations on the behaviour of galvanized HSS connections under static and fatigue loadings. The combined effects of cold-forming, welding, galvanizing, strain ageing, liquid metal embrittlement and vent holes on the joint capacities will be investigated. Supplemental rules to HSS manufacturing specifications and crack control guidelines will be generated to: (1) help Canadian steel manufacturers, fabricators and galvanizers optimize their production processes; and (2) help Canadian engineers specify appropriate levels of counter-measures to minimize the risk of cracking in HSS components during hot-dip galvanizing. The research will also provide a better understanding of the characteristics and structural performance of galvanized HSS connections. Design guidelines and recommendations for robust, cost-effective and long-lasting tubular structures will be established.*** Structures composed of high-performance steel have obvious advantages in economical, environment protection and energy-saving aspects. However, the design rules in the current Canadian steel design specification, which are intended for conventional steel, are limiting engineers from fully utilizing the structural and architectural advantages of the “new-generation” very-high-strength cold-formed HSS with inherent low levels of residual stress. The research will generate supplemental rules to the existing design specification to facilitate the application of the new technology. Validation of design guidelines and recommendations will be achieved by laboratory experiments and computer modelling.