Effective Cyclic Energy as a Measure of Seismic Demand

Structural damage during strong ground shaking is associated with both the seismic input energy and the ability of structural components to dissipate energy through viscous damping and inelastic cyclic response. The correlation of the damage potential of ground motions with seismic energy demand is an important element in developing energy-based design methodologies. This article proposes a new measure of the severity of ground motions by introducing the concept of effective cyclic energy (ECE) defined as the peak-to-peak energy demand (sum of hysteretic and damping energies) imposed on a structure over an effective duration that is equivalent to the time between two zero-crossings of the “effective velocity pulse.” The proposed energy measure, which is dependent on the characteristics of the ground motion, is shown to be well correlated with peak seismic demand for a range of system parameters. The development of ECE also provides a basis for defining a non dimensional response index (γ eff ) to quantify the destructive potential of ground motions. The effectiveness of the new index parameter is validated using an extensive set of near-fault accelerograms and also compared to other ground motion severity indices. Finally, ECE demand of a MDOF system is estimated through modal-energy-decomposition of elastic and inelastic SDOF systems, and the concept of ECE spectrum is proposed to estimate the modal target energy demands for performance evaluation of structures.

[1]  Angelo D'Ambrisi,et al.  Nonlinear statistic and dynamic analysis of reinforced concrete subassemlages. Report No. UCB/EERC 92/08, Earthquake Engineering Research Center, University of California at Berkeley, Berkeley, California, U.S.A., 1992 , 1992 .

[2]  Amador Teran-Gilmore,et al.  A Parametric Approach to Performance-Based Numerical Seismic Design , 1998 .

[3]  Sashi K. Kunnath,et al.  EVALUATION OF SEISMIC DEFORMATION DEMANDS USING NON-LINEAR PROCEDURES IN MULTISTORY STEEL AND CONCRETE MOMENT FRAMES , 2004 .

[4]  Sashi K. Kunnath,et al.  Cumulative damage‐based inelastic cyclic demand spectrum , 2004 .

[5]  Enrique Hernández-Montes,et al.  AN ENERGY-BASED FORMULATION FOR FIRST-AND MULTIPLE-MODE NONLINEAR STATIC (PUSHOVER) ANALYSES , 2004 .

[6]  Jaime E. Garcia,et al.  Hysteretic energy spectrum and damage control , 2001 .

[7]  Fabrizio Mollaioli,et al.  An energy-based methodology for the assessment of seismic demand , 2001 .

[8]  Sashi K. Kunnath,et al.  Assessment of current nonlinear static procedures for seismic evaluation of buildings , 2007 .

[9]  Peter Fajfar,et al.  Consistent inelastic design spectra: hysteretic and input energy , 1994 .

[10]  Enrico Spacone,et al.  A BEAM ELEMENT FOR SEISMIC DAMAGE ANALYSIS , 1992 .

[11]  A. Chopra,et al.  Comparing response of SDF systems to near‐fault and far‐fault earthquake motions in the context of spectral regions , 2001 .

[12]  M. Constantinou,et al.  Elastic and Inelastic Seismic Response of Buildings with Damping Systems , 2002 .

[13]  Polat Gülkan,et al.  Site-Dependent Spectra Derived from Ground Motion Records in Turkey , 2004 .

[14]  Mihailo D. Trifunac,et al.  On the correlation of seismic intensity scales with the peaks of recorded strong ground motion , 1975 .

[15]  Peter Fajfar,et al.  Consistent inelastic design spectra: Strength and displacement , 1994 .

[16]  Sashi K. Kunnath,et al.  Adaptive Modal Combination Procedure for Nonlinear Static Analysis of Building Structures , 2006 .

[17]  S. Kunnath,et al.  Relevance of Absolute and Relative Energy Content in Seismic Evaluation of Structures , 2008 .

[18]  Anil K. Chopra,et al.  Evaluation of modal pushover analysis using generic frames , 2003 .

[19]  Sashi K. Kunnath,et al.  Modeling and Response Prediction in Performance-Based Seismic Evaluation: Case Studies of Instrumented Steel Moment-Frame Buildings , 2004 .

[20]  Theodore V. Galambos,et al.  Earthquake Load for Structural Reliability , 1989 .

[21]  D. Boore.  Effect of Baseline Corrections on Displacements and Response Spectra for Several Recordings of the 1999 Chi-Chi, Taiwan, Earthquake , 2004 .

[22]  A. Papageorgiou,et al.  Near‐fault ground motions, and the response of elastic and inelastic single‐degree‐of‐freedom (SDOF) systems , 2004 .

[23]  Sashi K. Kunnath,et al.  Effects of Fling Step and Forward Directivity on Seismic Response of Buildings , 2006 .

[24]  Eduardo Miranda,et al.  Inelastic displacement ratios for evaluation of existing structures , 2003 .

[25]  Peter Fajfar,et al.  Equivalent ductility factors, taking into account low‐cycle fatigue , 1992 .

[26]  Haluk Sucuoǧlu,et al.  Energy‐based hysteresis and damage models for deteriorating systems , 2004 .

[27]  James O. Jirsa,et al.  A Damage Model for Practical Seismic Design that Accounts for Low Cycle Fatigue , 2005 .

[28]  W. B. Joyner,et al.  Equations for Estimating Horizontal Response Spectra and Peak Acceleration from Western North American Earthquakes: A Summary of Recent Work , 1997 .

[29]  F. Manouchehri Dana,et al.  Introduction of the most suitable parameter for selection of critical earthquake , 2005 .

[30]  C. Uang,et al.  Evaluation of seismic energy in structures , 1990 .

[31]  Chia-Ming Uang,et al.  A procedure for evaluating seismic energy demand of framed structures , 2003 .

[32]  Halûk Sucuoğlu,et al.  Statistical evaluation of the damage potential of earthquake ground motions , 1998 .

[33]  J. Bray,et al.  Characterization of forward-directivity ground motions in the near-fault region , 2004 .