Towards the Design of Durable and High-Performance Tubular Structures

基础设施是加拿大生活方方面面的核心。基础设施的过早恶化和损害的修复是数十亿美元的问题。拟议的研究计划的动机是越来越多的报告称，北美各地的镀锌钢结构在使用中性能不佳，甚至有危险倒塌。将开发解决方案，以改善桥梁、公路和停车场结构、工业厂房和由镀锌空心结构段(HSS)构件和连接组成的输电塔的结构性能并延长其使用寿命。长期目标是促进加拿大耐用和高性能基础设施的设计、制造、施工和维护。*这项研究将首先解决热镀锌过程中高速钢组件开裂的当代问题，然后对镀锌高速钢连接在静态和疲劳载荷下的行为进行一系列实验和数值研究。将研究冷成形、焊接、镀锌、应变时效、液态金属脆化和通气孔对接头性能的综合影响。将制定高速钢制造规范和裂纹控制指南的补充规则，以：(1)帮助加拿大钢铁制造商、制造商和电镀厂优化其生产工艺；以及(2)帮助加拿大工程师指定适当的应对措施，以最大限度地减少热镀锌过程中高速钢部件开裂的风险。研究还将有助于更好地了解镀锌高速钢结构节点的特点和结构性能。将制定坚固、经济、耐用的钢管结构的设计指南和建议。*由高性能钢组成的结构在经济、环保和节能方面具有明显的优势。然而，现行加拿大钢材设计规范中针对传统钢材的设计规则限制了工程师充分利用“新一代”超高强度冷弯HSS的结构和建筑优势，这种钢结构具有固有的低残余应力水平。这项研究将对现有的设计规范产生补充规则，以促进新技术的应用。将通过实验室实验和计算机模拟来验证设计准则和建议。

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.