Ductile Web Fracture Initiation in Steel Shear Links

Tests conducted in the 1980s showed that well-detailed short shear links can exhibit stable and ductile cyclic behavior. Recent tests of prevailing A992 rolled shapes revealed that shear links designed according to current seismic specifications can fail by ductile fracture in the link web, a mode of failure that was not observed in earlier tests. This paper investigates the observed ductile fractures through computational structural simulation. An existing criterion for judging the propensity for ductile fracture initiation in steel is modified based on published tests results for notched bars to better pinpoint the location of ductile fracture initiation. Validated finite- element analyses of previously tested shear links are conducted and the results postprocessed to evaluate the potential for ductile fracture of specimens with several different types of details. Reasons for the occurrence of web fractures in new A992 steel beams as opposed to older links are discussed. An alternative stiffener configuration that mitigates ductile fracture and is at the same time practical to construct is proposed.

[1]  Amit Kanvinde,et al.  Micromechanical simulation of earthquake-induced fracture in steel structures , 2004 .

[2]  A. Gurson.  Continuum Theory of Ductile Rupture by Void Nucleation and Growth: Part I—Yield Criteria and Flow Rules for Porous Ductile Media , 1977 .

[3]  J. Toribio.  of high-strength steel notched bars , 1998 .

[4]  Frieder Seible,et al.  CYCLIC TESTING OF BUILT-UP STEEL SHEAR LINKS FOR THE NEW BAY BRIDGE , 2003 .

[5]  E. P. Popov,et al.  Seismic Behavior of Active Beam Links in Eccentrically Braced Frames , 1983 .

[6]  Claudio Ruggieri,et al.  Micromechanics modelling of ductile fracture in tensile specimens using computational cells , 2003 .

[7]  A. Needleman,et al.  Analysis of the cup-cone fracture in a round tensile bar , 1984 .

[8]  Donald A. Koss,et al.  Ductile failure as a result of a void-sheet instability: experiment and computational modeling , 1998 .

[9]  G. Rousselier,et al.  Ductile fracture models and their potential in local approach of fracture , 1987 .

[10]  A. Pineau,et al.  Coalescence-Controlled Anisotropic Ductile Fracture , 1999 .

[11]  Sherif El-Tawil,et al.  Pushover of Hybrid Coupled Walls. I: Design and Modeling , 2002 .

[12]  T. Okazaki,et al.  RECENT RESEARCH ON LINK PERFORMANCE IN STEEL ECCENTRICALLY BRACED FRAMES , 2002 .

[13]  M. Zaidman,et al.  Constitutive models for porous materials with evolving microstructure , 1994 .

[14]  Sashi K. Kunnath,et al.  Inelastic Behavior and Design of Steel Panel Zones , 2000 .

[15]  J. Hancock,et al.  On the mechanisms of ductile failure in high-strength steels subjected to multi-axial stress-states , 1976 .

[16]  A. C. Mackenzie,et al.  On the influence of state of stress on ductile failure initiation in high strength steels , 1977 .

[17]  J. Lemaître.  A CONTINUOUS DAMAGE MECHANICS MODEL FOR DUCTILE FRACTURE , 1985 .

[18]  Aleksandar Sedmak,et al.  Prediction of ductile fracture initiation using micromechanical analysis , 2004 .

[19]  Egor P. Popov,et al.  Design considerations for shear links in eccentrically braced frames , 1983 .

[20]  V. Tvergaard.  Influence of voids on shear band instabilities under plane strain conditions , 1981 .

[21]  F. A. McClintock,et al.  A Criterion for Ductile Fracture by the Growth of Holes , 1968 .

[22]  D. M. Tracey,et al.  On the ductile enlargement of voids in triaxial stress fields , 1969 .

[23]  Hitoshi Kuwamura,et al.  Ductile Crack as Trigger of Brittle Fracture in Steel , 1997 .