A Damage Model for Practical Seismic Design that Accounts for Low Cycle Fatigue

Abstract

The structural properties of a structure deteriorate when deformations reach the range of inelastic behavior. A possible consequence of deterioration of the hysteretic behavior of a structure is failure of critical elements at deformation levels that are significantly smaller than its ultimate deformation capacity. Seismic design methodologies that account for low cycle fatigue can be formulated using the concept of target ductility. The practical use of one such methodology requires the consideration of simple low cycle fatigue models that consider the severity of repeated loading through a normalized plastic energy parameter. The inconsistencies inherent to the use of such indices can be corrected through simple empirical rules derived from an understanding of the effect of the history of energy dissipation in the assessment of the level of structural damage.

Structural reliability evaluation considering capacity degradation over time

“…A consequence of this is the failure of critical elements at deformation levels that are significantly smaller than their ultimate deformation capacities under unidirectional loading. This failure mode is commonly called low-cycle fatigue [8][9][10][11]. (iii) Fatigue is one of the most common damage types that may occur when structures are subjected to repetitive or cyclic load patterns.…”

Consideración Explícita Del Daño Acumulado en El Diseño Sismico De Estructuras a Través De Factores De Reducción De Resistencia Por Ductilidad

“…La hipótesis de Miner considera que el daño inducido por cada excursión plástica es independiente del daño producido por cualquier otra incursión, de tal manera que se requiere de una convención clara para definir y delimitar cada excursión (Powell y Allahabadi 1987, Terán y Jirsa 2005. Cosenza y Manfredi (1996) han formulado la hipótesis de Miner conforme a lo siguiente:…”

Reliability-based evaluation of steel structures using energy concepts

“…Although there is no agreement on how energy demands should be accounted for during seismic design, the experimental and analytical evidence gathered so far indicates that structures can be protected from the effect of cumulative plastic demands by limiting their maximum deformation demand during an earthquake ground motion within a threshold that is significantly smaller than their ultimate deformation capacity under unidirectional loading [14,[16][17][18]. In cases like these, seismic design should be updated to explicitly account for the effect of the cumulative plastic deformation demands, and thus, indirectly, for the effect of strong motion duration on structural performance [12,14,16,17,19,20].…”

“…The superposition of the conclusions derived from the analytical and experimental research with the field evidence gathered after the 1985 Mexican Earthquakes consistently shows that structures subjected to the narrow-banded motions generated in the Lake Zone of Mexico City are likely to undergo severe plastic demands that if not accounted for during design can lead to unreliable performance [9][10][11][12][13]. Teran and Jirsa [14] observe that dissipated hysteretic energy demanded by narrowbanded motions can be three to four times larger than those corresponding to firm soil. As a consequence, they offer the following conclusion: "displacement-control seismic design methodologies seem to provide adequate level of safety for the design of structures with stable hysteretic behavior and subjected to "typical" firm soil motions.…”