The Earthquake Engineering Online Archive

Testing and Simulation of Ultra-Low Cycle Fatigue and Fracture in Steel Braces

Fell, Benjamin V.; Myers, A. T.; Deierlein, Gregory G.; Kanvinde, Amit M.

Proceedings of the 8th U.S. National Conference on Earthquake Engineering, San Francisco, Calif., Paper No. 587, 2006, PDF (408 KB)

Preliminary experimental and simulation results are presented for the first phase of testing for a Network of Earthquake Engineering Simulation Research (NEESR) project to investigate Ultra-Low Cycle Fatigue (ULCF) in large-scale steel bracing members. The tested members represent braces in Special Concentrically Braced Frame (SCBF) systems that undergo severe cyclic inelastic deformations accompanied by global and local buckling eventually leading to ULCF-induced fracture. The experimental findings are complemented by detailed continuum-based FEM and line-element-based OpenSEES analyses. The ULCF process itself is simulated through micromechanics-based models that capture the fundamental processes of void growth, collapse, and damage responsible for ULCF. The paper briefly describes existing models for base metals and ongoing efforts to develop models for weld metals. The paper concludes with a commentary on the methodology of utilizing micromechanics based fracture models for large-scale structural components where modeling of phenomena such as local and global buckling may need explicit attention. Future experiments and research directions are discussed.

Available online: http://library.eerc.berkeley.edu/documents/8NCEE/fell-myers-ultra-low-cycle.pdf