Cumulative damage‐based inelastic cyclic demand spectrum

Abstract

SUMMARYThe estimation of cyclic deformation demand resulting from earthquake loads is crucial to the core objective of performance-based design if the damage and residual capacity of the system following a seismic event needs to be evaluated. A simpliÿed procedure to develop the cyclic demand spectrum for use in preliminary seismic evaluation and design is proposed in this paper. The methodology is based on estimating the number of equivalent cycles at a speciÿed ductility. The cyclic demand spectrum is then determined using well-established relationships between seismic input energy and dissipated hysteretic energy. An interesting feature of the proposed procedure is the incorporation of a design spectrum into the proposed procedure. It is demonstrated that the force-deformation characteristics of the system, the ductility-based force-reduction factor R , and the ground motion characteristics play a signiÿcant role in the cyclic demand imposed on a structure during severe earthquakes. Current design philosophy which is primarily based on peak response amplitude considers cyclic degradation only in an implicit manner through detailing requirements based on observed experimental testing. Findings from this study indicate that cumulative e ects are important for certain structures, classiÿed in this study by the initial fundamental period, and should be incorporated into the design process.

Damage-Based Seismic Performance Evaluation of Reinforced Concrete Frames

“…In experiments carried out by Brown and Kunnath (2004), the fatigue life of reinforcing bars is computed using an effective length that includes the buckling zone. Additional details to estimate (2N f ) j can be also found in Kunnath and Chai (2004).…”

Direct damage controlled seismic design of plane steel degrading frames

“…Among the works dealing with damage-based seismic design methods one can mention the following representative ones: i) those of Park et al (1987) with an explicit tolerable level of damage and of Panyakapo (2008) based on a damage-based capacity-demand method ii) those of Aschheim (2002) and Safar and Ghobarah (2008) based on yield displacement spectra where damage is considered indirectly iii) those of Kawashima and Aizawa (1986), Ballio and Castiglioni (1994), Tiwari and Gupta (2000), Kunnath and Chai (2004), Lu and Wei (2008) and Teran-Gilmore and BahemaArredondo (2008) based on inelastic spectra obtained with the aid of a damage dependent behavior or strength reduction factor iv) those of Malhotra (2002), Bozorgnia and Bertero (2004), Panyakapo (2004) and Ghobarah and Safar (2010) employing damage or cyclic demand spectra. In this paper, the Direct Damage Controlled Design (DDCD) method, a new design method for steel moment resisting framed structures under earthquake excitation, is proposed.…”

“…In Hatzigeorgiou and Beskos (2007) damage was an internal variable in the stress-strain relation for concrete and computed as a function of deformation, while in Kamaris et al (2009) damage was expressed in the form of a damage index defined for simple elastoplastic behavior without cyclic deterioration in stiffness and strength as it is presently the case. Furthermore, the present method does not require directly or indirectly special damage-based design spectra and associated damage dependent behavior or strength reduction factors as it is the case with Kawashima and Aizawa (1986), Ballio and Castiglioni (1994), Tiwari and Gupta (2000), Kunnath and Chai (2004), Lu and Wei (2008), Teran-Gilmore and Bahema-Arredondo (2008), Malhotra (2002), Bozorgnia and Bertero (2004), Panyakapo (2004) and Ghobarah and Safar (2010), works in the framework of three damage levels obtained herein through extensive parametric studies, which is not the case with the abovementioned authors and provides all the three aforementioned design options instead of just the first and/or the second design option as it is the case with Kawashima and Aizawa (1986), Ballio and Castiglioni (1994), Tiwari and Gupta (2000), Kunnath and Chai (2004), Lu and Wei (2008), Teran-Gilmore and Bahema-Arredondo (2008), Malhotra (2002), Bozorgnia and Bertero (2004), Panyakapo (2004) and Ghobarah and Safar (2010). To be sure, Abbas and Takewaki (2010) and Abbas (2011) have also considered the aforementioned third design option (determine the seismic load for a desired damage level) separately by employing a completely different approach.…”

Influence of Low-Cycle Fatigue and Corrosion Phenomena on the Ductile Behaviour of Steel Reinforcing Bars

“…Many works were presented in the current literature dealing with the evaluation of the effective seismic demand on different kinds of structures and sub-structures [4,6,7,8,9,10,11,12] but in general, no information were provided about the effective ductility demand on steel reinforcing bars, in terms of both strain level and energy dissipation. In their work, Barrera et al [13] presented the results of experimental tests executed on r.c.…”