Direct tensile test. Stability and bifurcation

Zdenek P Bazant*, Luigi Cedolim

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Unnotched specimens of quasibrittle materials that exhibit post-peak strain softening do not deform symmetrically in a direct tension test. The phenomenon (which is similar to the recently discovered behavior of notched tensile fracture specimens) is illustrated using a simple model in which the specimen consists of two bars of unequal length, joined by a strain-softening link. The equilibrium path bifurcates and the thermodynamic criterion of stable path requires the specimen to flex to one side, even if the geometry is perfect and if the straightening effect of the moment of the axial force about the centroid of the deflected cross section is taken into account. The bifurcation behavior is analogous to Shanley's bifurcation in elastoplastic columns. In absence of rotational restraints at the ends, the specimen fails right after the peak load. The lateral flexing can be retarded by providing rotational restraints at the specimen ends.

Original languageEnglish (US)
Title of host publicationProceedings of Engineering Mechanics
PublisherPubl by ASCE
Number of pages4
ISBN (Print)0872628671
StatePublished - Jan 1 1992
EventProceedings of the 9th Conference on Engineering Mechanics - College Station, TX, USA
Duration: May 24 1992May 27 1992


OtherProceedings of the 9th Conference on Engineering Mechanics
CityCollege Station, TX, USA

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Architecture


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