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Title: Deflection at Incipient Failure as Warning-of-Failure Metric

Author(s): Marcie van Weerdhuizen and F. Michael Bartlett

Publication: Structural Journal

Volume: 117

Issue: 4

Appears on pages(s): 233-241

Keywords: existing structure assessment; flexural ductility; plastic hinge length; reinforced concrete; reinforcement ratio; reliability index; structural safety; Warning Factor

Date: 7/1/2020

The target reliability index for the assessment of an existing flexural element depends on the warning of failure provided and therefore on the total deflection at incipient failure. Sensitivity analyses accounting for both the linear-elastic-cracked and plastic responses indicate that the warning of failure depends on the ductility of critical cross sections (and therefore on the flexural reinforcement ratio) and the length of the plastic hinge regions (and therefore on the applied load configuration). Structural redundancy typically reduces the total deflection at incipient member failure and therefore is an inconsistent indicator of warning of failure. The deflections at incipient failure can be normalized as fractions of the span length to quantify the Warning Factor, W, as a function of the reinforcement ratio, span length, and effective beam depth. This continuous variable can replace existing discretized values of the Warning Factor based on somewhat subjective classifications of ductility and redundancy.


Electronic Structural Journal


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