Use of HSS and VHSS in steel structures in civil and offshore engineering

Abstract

The use of high-strength steels (HSS, 460 < f y ≤ 700 MPa) and particularly very high-strength steels (VHSS, f y > 700 MPa) is limited in steel structures in civil and offshore engineering. This is due to a lack of experience in structures made of these materials and a lack of understanding of the structural performance of HSS and VHSS. The main questions that are unanswered concern the topics of static strength, fracture toughness, fatigue, material (in) homogeneity and manufacturing. With regard to the static strength, it is unclear as to whether requirements currently stated in the Eurocodes for the yield-to-tensile strength ratio (f y /f u ) as well as the Von Mises yield criterion are applicable to structural designs in HSS and VHSS. With regard to fracture toughness, it is unclear as to whether the crack arrest capability of HSS and VHSS is currently sufficiently covered in Eurocode requirements. Furthermore, Eurocode requirements for maximum plate thickness are quite restrictive if they are extrapolated to HSS and VHSS. Other questions relate to the homogeneity of the material. Are HSS and VHSS sufficiently resistant to lamellar tearing and is material testing in different orientations necessary? This study gives an overview of the relevant questions, outlines the requirements in the current Eurocode system, presents answers to these questions where possible and provides a recommended research focus for the coming years.

Fatigue Behaviour of Offshore T-Weld Connections Repaired by Grinding and Wet Welding

“…authors reported relatively low fatigue life, which resulted from the formation of imperfections during the welding process [2]. However, the fatigue strength behavior of welded joints is independent of the fatigue behavior of parent material in an as-welded state [3]. Therefore, Berg et al [4] performed research work to improve the fatigue strength on welded joints ultra-high strength steels (UHSS) by hammer peening.…”

“…1 GBF: Ferrite with primary grain boundary. 2 FS: Ferrite side plate 3. FSA: Ferrite with second aligned phase, upper bainite.…”

Fatigue strength of normal and high strength steel joints improved by weld profiling

“…While high-strength structural steels are readily available with yield strength even above 1000 MPa and are regulated in standards for steel constructions like Eurocode 3 up to 700 MPa, their use remains limited to day [15]. Although, high-strength steel offers extensive design potential, typical civil and offshore engineering structures are to this day mainly build of S355 steel [16].…”

Bond characteristics between high/ultra-high strength steel and ultra-high modulus CFRP laminates

“…The applications of HSS and UHSS are becoming significantly attractive in variety of engineering sectors such as bridge construction [20], building structures [21], offshore [22] etc. With the increasing interest to use HSS/UHSS, rehabilitation and strengthening of struc tures made of such steel grades especially at the welded area becomes vital.…”