Ultiaate behavior strength which obtained from the bending : the relationships between and l/a*l/YR,where the material. could be approximated linear function of the products l/a*l/YR. the failure of bending test specimens. failed by local buckling of the flanges fractured from ductile cracks, which had in the welded joint at the corner of the section is considered that cracks occured in the first, rapidly through the wall thickness. Since three of the four fractured specimens locally buckled and broken after attaining the peak of curves, they sufficient ductility. at toes observed

doi:10.1201/9781482271355-90

Chapter

Ultiaate behavior strength which obtained from the bending

Chapter

the relationships between and l/a*l/YR,where the material. could be approximated linear function of the products l/a*l/YR. the failure of bending test specimens. failed by local buckling of the flanges fractured from ductile cracks, which had in the welded joint at the corner of the section is considered that cracks occured in the first, rapidly through the wall thickness. Since three of the four fractured specimens locally buckled and broken after attaining the peak of curves, they sufficient ductility. at toes observed

ABSTRACT

3.3 Ultiaate behavior The maximum strength Mmax which was obtained from the bending tests exceeded Mp of the specimen as shown in Table 3. Figure 5 shows the relationships between Mmax/Mp and l/a*l/YR,where YR is yield ratio of the material. Mmax could be approximated by a linear function of the products l/a*l/YR. Table 4 shows the failure mode of bending test specimens. Thirteen specimens failed by local buckling of the flanges and 4 specimens were fractured from ductile cracks, which had occured in the welded joint at the corner of the section and propagated through column flanges. Cracks occured at the toe of the joint welds for specimen No.7 and No.lS. For specimen No.8 and No.17, it is considered that cracks occured in the weld metal at first, then propagated rapidly through the wall thickness. Since three of the four fractured specimens (except No.8) were locally buckled and broken after attaining the peak of M-8 curves, they showed sufficient ductility. Ductile cracks which had occured at weld toes were observed on 7 specimens containing 3 welded RHSs and 4 press formed RHSs. Cracks did not propagate in welded RHSs, while 2 types of phenomenon were observed in press formed RHSSi one was the same as welded column and for the other the crack continued to grow. It is suggested that several differences in mechanical properties of joints, profile of weld toe and strain concentration to the corner of the section produced these different phenomena. At first, it must be emphasized that weld heat input was much different between welded RHS specimens and press formed RHS specimens. When heat input increases, grain size in both weld metal and HAZ also grows, which results in the decrease of mechanical properties for both strength and toughness,Gooch, T.G.(1989).