| A conclusion that properties of welded joint of steel 907A can be replaced by welded metal are obtained on the basis of tension experiment and finite element simulation analysis for fracture behavior on welded metal sample of the steel.The boundaries to distinguish fracture characteristic zones between plain strain, elastic-plastic and plastic for structural steel are discussed. The Fracture Characteristic Analysis Map (FCAM) of steel 907A and its welded joint was established, according to the principles that "not only considers preventing fracture but also takes into accounts the cost".The limitations of traditional fracture design criterions are discussed. It is pointed that fracture behavior for steel constructions are influenced by loading rate, thickness, crack toughness, environmental temperature simultaneously.A dynamic fracture control design criterion was proposed on the base of the FCAM of steel 907A. Applying the criterion to design steel 16Mnq satisfactorily conforms to the conclusion of British bridge standard.lnK1d and lnσyd Relation Map of structural steel is built, taking advantage of constitutive equation of material:σyd=σs [1+(ε/r)m][αexp(-βT)]. Applyingthe map to evaluate 24mm plate of steel 907A (K=105MPa(m/s)1/2) has a goodagreement with conclusion that FCAM provides.Ratio Margin Map and Critical Size and Toughness Level Relation Map forstructural steel have been built, taking advantage of the parameter K1c/σys (K1d/σyd)In the second section of this thesis, Design for Hopkinson Pressure Bar is proposed in terms of material and size.
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