Parameter Analysis of Single-Layer Ellipsoid Lattice Shell Isolation Bearing under Multi-dimensional Seismic Wave

摘要

The protection of steel by galvanizing dates back to 1837. It has been used extensively for protecting structural steel over the years and has provided reliable, predictable performance. In recent years, the development of higher strength steels has resulted in the need to reassess the capabilities of galvanizing to ensure that structural integrity is not compromised. This paper addresses three recent developments that structural designers should be aware of; viz. The new international standards relating to the galvanizing process and the design for galvanizing, the require ments for the galvanizing of high strength fasteners and the galvanizing capabilities of new higher strength steels. EN ISO 1461: Hot dip galvanized coatings on fabricated iron and steel articles-Specifications and test methods and EN ISO 14713 Protection against corrosion of iron and steel in structures-Zinc and aluminium coatings-Guidelines were both revised in 2009. ISO 1461 provides new guidelines in terms of zinc melts and sampling for compliance. In spection of galvanized items is an area where more education of suppliers and users would eliminate many misunder standings. ISO 14713 now provides useful corrosion performance data in terms of the corrosivity of environments and allows specifiers to predict the life expectancy of the coating with confidence. This is discussed in detail. The galvanizing of high strength fasteners has often been misunderstood with failures occurring due to either poor process control or incorrect article preparation prior to galvanizing. This has led to the incorrect conclusion in certain structural designing circles that the galvanizing of fasteners is problematic. This paper will cover the issues and pro vide guidelines for specifiers to avoid high strength fastener failures. Finally, in 1975 the British Nonferrous Technology Centre produced a report characterising the galvanizing of struc tural steels and their weldments and concluded that the galvanizing process was not detrimental to the mechanical properties of the articles. This study provided the background to the current use of galvanizing on welded structural steels. The study was recently repeated for S275JR and S355K2 steels to BS EN 10025-2:2004, P460NL1 steel to BS EN10028-3:2003 and ASTM A36,A572 Grade 50 and Grade 65 steels. Any differences in the mechanical prop erties of as received plate and after galvanized will be discussed.