摘要
本文叙述来自世界主要生产商的钢产品及钢材料,可在"同一平台"的基础上得以被使用。香港钢结构规范通过采用由澳大利亚、中国、日本、美国和欧盟(英国版本)等五个地区的认可标准所给予一致的参考标准,得以实现。普通强度钢材的屈服强度在215N.mm-2到460N.mm-2范围内变化。这一范围涵盖了中国最低级别的Q235钢。高强度钢材的屈服强度在460N.mm-2到690N.mm-2范围内变化,这些钢材一般只以板材形式呈现。尽管690N.mm-2是一般常用的钢材屈服强度上限值,世界上一些专业生产商仍可提供多种屈服强度在500到900N.mm-2范围内的钢材,而超高强度钢材的屈服强度则在690N.mm-2以上。在使用一些无合格证书的钢材或屈服强度超过460N.mm-2的钢材时,本规范不建议采用塑性分析设计方法。对于在设计温度下如何选择合适的钢材以提供足够的延性,本规范作出了规定。本规范要求通过保证加工中不出现巨大且具影响的缺陷,并采用质量上具有足够切口韧性的钢材,来避免产生脆性断裂。当钢材最大板厚的计算背离本规范的限值时,需要进行特殊的断裂力学评估,并需用断裂力学计算提供调整方案。
The Code allows the use of steel materials from worldwide suppliers on a ＂level playing field＂ basis.This is achieved by using an approach based on a consistent set of acceptable reference materials standards from the five major international regions which produce structural steels.Normal strength steel is defined as having yield strength ranging from 215N·mm-2（170N·mm-2 for thick plates） to 460N·mm-2.This range includes the lowest grade China steel Q235 up to the highest normally available structural steel strengths（the previously designated grade 55 steel to BS4360）.For normal strength steel without valid mill certificates may be used and is classified as uncertified steel.Various very high strength steels with yield strengths lying in the range from 460 to 900N·mm-2 are available from specialist manufacturers worldwide,even though 690N·mm-2 is a more widely available upper yield strength value.Plastic analysis and design is not permitted for uncertified steel or for steel with yield strength greater than 460N·mm-2.Brittle fracture can occur in welded steel structures subjected to tension stresses at low service temperatures.In certain situations,where fracture-sensitive connection details,inappropriate fabrication conditions or use of low toughness weld materials are used,it can also occur at normal temperatures.The problem is tackled by specifying steels and welded joints with appropriate grade of fracture toughness,usually implemented in practice by specifying sub-grade of notch ductility in the Charpy test.Higher sub-grade is required for thicker steels and joints.The Code gives guidance on avoidance of brittle fracture by specifying the maximum plate thickness,assuming the plate is free from significant surface defect and by using a steel quality with adequate notch toughness as quantified by Charpy impact properties.When the maximum plate thickness is exceeded,fracture mechanics analysis should be employed by experts to assess the notch toughness.
出处
《建筑钢结构进展》
2010年第1期10-17,共8页
Progress in Steel Building Structures
