Fatigue strength of welded connections made of very high strength cast and rolled steels

Fatigue strength of welded connections made of very high strength cast and rolled steels

Pijpers, R.J.M.

Bijlaard, F.S.K. (promotor)

Civil Engineering and Geosciences

Bouw

2011-10-18

Although Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years, the use of these steels in the civil engineering industry is still uncommon. The main objective of the research is the determination of the fatigue strength of welded connections made of VHSS. The research comprised of a literature study, an experimental study and an analysis of the results. An effective application of VHSS is expected in truss-like structures, typically made of hollow sections. Truss structures enable full exploitation of the high material strength of VHSS, because in such stiff structures the deflection is not the governing the design criterion. Improved design of VHSS truss structures should incorporate the application of very high strength cast joints, as an appropriate design of cast joints limits the stress concentrations in the joint. The fatigue strength of cast joints will therefore be relatively high compared to that of regular steel welded joints, as the stress concentration of the connection is limited and welds are shifted out of critical zones. Three types of specimens were fatigue tested in the study: specimens of base material, of welded plates and of trusses made of circular hollow sections (CHS) and cast joints. Plate test specimens were derived from base material of rolled steel and welded cast and rolled plates. The main conclusion of the research is that higher yield strength increases crack initiation life of base material and welded connections in case of low notch stress concentration and small initial imperfections. Crack propagation life is independent of yield strength.

Very High Strength Steel
Cast Steel
High Cycle Fatigue
Welded Connections

http://resolver.tudelft.nl/uuid:deddef38-0f69-4e27-be4e-c7f6850efd51

9789077172797

Institutional Repository

doctoral thesis

(c) 2011 Pijpers, R.J.M.