Flexural Strength And Ductility Of Hybrid Girders Fabricated From High Performance Steel

High Performance Steel (HPS) with yield strength of 485 MPa has high strength in addition to good weldability, fracture toughness, and corrosion resistance. As High Performance Steel plates are in use in highway bridges, the steel types and articles in bridge codes must be modified. To make the High Performance Steel paltes popularization and security application in highway bridges, testing study and finite elemet analysis were performed on hybrid I-girders fabricated from High Performance Steel plates in this paper, in addition, its failure mechanism had been studied, and at last, the influence rules and reasonable values of the paramerters were got. In detail, the following aspects were investigated:1. Finite element simulations were performed, as to two pieces of girders fabricated from HPS-690W and tested by professor Sause in Lehigh University, using the commercially general-purpose finite element program ANSYS9.0, to get the accurate finite element model for simulating the mechanical behavior of the specimens. And moreover the failure mechanism of the girders was in study.2. Material tesion test was performed to get the mechanic property of 12mm HPS-485W plates and the whole engineering stess-strain curve that was proceesed to obtain the true stress-nature strain curve, yield shtreng and young's modulus. Three specimens were designed, in which 12mm HPS-485W plates and 8mm Q235 plates were used, and moreover simulated and analyzed by the finite element model wich was checked by test specimens tested by professor Sause to capture the failure modes and buckling location of the specimens. At last, typical measuring points of strain and deflection were determined.3. Three testing specimens by hybride design method were tested in bridge laboratory of Chang an University. The results of testing girders were processed, were compared with the results from finite element anslysis. And more over, the failure mechanism of specimens was studied in-depth. The compared results showed that the web buckling strength had notable effection on the flexural strength of high performance hybride girders.4. Parametric study about the effect of different parameters on the strength and ductility of hybrid I-girders fabricated from HPS-485W plates was performed by the checked finite element model. These parameters are the normalized flange slenderness, the normalized web slenderness,the cross section aspect ratio, geometric imperfections, lateral bracing system, match of the materials about flange and web and so on.In the end, the research contents of this paper were summarized, and the suggestion of the further study were given also.