Hot-dip galvanized hollow structural sections - crack prevention and mechanical behaviour

热浸镀锌空心结构型材 - 裂纹预防和机械性能

• 批准号: 500838-2016
• 负责人: Sun, Min
• 金额: $ 1.46万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=618087
• 关键词: Hot; dip; galvanized; hollow; structural

The application of hot-dip galvanized cold-formed Hollow Structural Sections (HSS) in exposed steelstructures (e.g. bridges, transmission towers and sign supporting structures) is extremely popular due to theirsuperior strength-to-weight ratio, low initial cost, sustainability and aesthetics. Both HSS manufacturing andhot-dip galvanizing techniques have evolved over the years. However, the use of newly developed zinc bathmixtures together with thick-walled HSS resulting in significant damage in the latter in the form of crackingduring the galvanizing process, especially at comer regions of Rectangular Hollow Sections (RHS), has beenreported to be a widespread problem lately. In an even worse case, if such cracks do not cause visible damage to the section and remain undetected before the final product leaves the galvanizing shop, they can result in serious consequences on the performance of the structure. This research aims to investigate: (1) the prerequisites of cracking; (2) if hot-dip galvanizing-induced embrittlement is a concern for RHS with different cross-sectional dimensions and produced to different specifications; (3) the thresholds of wall thickness above which different levels of pre-galvanizing countermeasures for brittle cracking are needed; and (4) the detrimental/beneficial effects of hot-dip galvanizing on the mechanical behaviours of RHS.The long-term goals of this project are to: (1) provide guidelines to engineers, fabricators and galvanizers to minimize the risk of cracking in RHS during hot-dip galvanizing; (2) generate supplemental rules to HSS manufacturing specifications and crack control guidelines; and (3) provide a better understanding of the characteristics and structural performance of hot-dip galvanized RHS to facilitate its application.

热镀锌冷弯空心结构型材（HSS）由于其优越的强度重量比、低初始成本、可持续性和美观性，在外露钢结构（例如桥梁、输电塔和标志支撑结构）中的应用非常普遍。高速钢制造和热浸镀锌技术都经过多年的发展。然而，使用新开发的锌浴混合物与厚壁高速钢一起导致后者在镀锌过程中以裂纹的形式出现显著损伤，特别是在矩形空心型材（RHS）的角部区域，最近已被报道为一个普遍的问题。在更糟糕的情况下，如果这种裂纹不会对型材造成可见的损坏，并且在最终产品离开镀锌车间之前仍未被发现，则它们可能会对结构的性能造成严重后果。本研究旨在探讨：（1）开裂的先决条件;（2）对于不同截面尺寸和不同规格的RHS，热浸镀锌引起的脆化是否值得关注;（3）壁厚的阈值，在该阈值以上，需要不同程度的预镀锌对策来防止脆化开裂;以及（4）热浸镀锌对RHS机械性能的不利/有利影响。本项目的长期目标是：（1）为工程师、制造商和镀锌者提供指导，以最大限度地减少RHS在热浸镀锌过程中开裂的风险;（2）为高速钢制造规范和裂纹控制指南制定补充规则;以及（3）更好地了解热镀锌RHS的特性和结构性能，以促进其应用。