EQUIVALENT VISCOUS DAMPING EQUATIONS FOR DIRECT DISPLACEMENT BASED DESIGN

Estimation of equivalent viscous damping is an important step in the methodology of the direct displacement based design. Errors in the estimation of this parameter may lead to consequent errors in the ductility demand of the designed elements. Equivalent viscous damping estimated by Jacobsen's approach for steady-state harmonic response are compared with effective damping factors obtained from an iterative procedure using time — history analyses of single-degree-of-freedom systems. In order to separate the effects of elastic-viscous and hysteretic damping the designs and analyses were carried without elastic viscous damping. Six hysteretic models representing a wide range of hysteretic energy absorption characteristics and six artificial records were used in the analysis. It is found that in general Jacobsen's approach overestimates the values for equivalent viscous damping. Based on the analytical results, modified design equations for equivalent viscous damping are proposed.

[1]  Polat Gülkan,et al.  INELASTIC RESPONSES OF REINFORCED CONCRETE STRUCTURES TO EARTHQUAKE MOTIONS , 1977 .

[2]  G. W. Housner,et al.  Limit Design of Structures to Resist Earthquakes , 1956 .

[3]  R V Nutt,et al.  IMPROVED SEISMIC DESIGN CRITERIA FOR CALIFORNIA BRIDGES: PROVISIONAL RECOMMENDATIONS , 1996 .

[4]  Gian Michele Calvi,et al.  Concepts and procedures for direct displacement-based design and assessment , 2019, Seismic Design Methodologies for the Next Generation of Codes.

[5]  Mete A. Sozen,et al.  SUBSTITUTE-STRUCTURE METHOD FOR SEISMIC DESIGN IN R/C , 1976 .

[6]  Anil K. Chopra,et al.  Dynamics of Structures: Theory and Applications to Earthquake Engineering , 1995 .

[7]  Mjn Priestley,et al.  VISCOUS DAMPING IN SEISMIC DESIGN AND ANALYSIS , 2005 .

[8]  M. J. Nigel Priestley,et al.  Myths and fallacies in earthquake engineering , 1993 .

[9]  Gian Michele Calvi,et al.  A DISPLACEMENT-BASED APPROACH FOR VULNERABILITY EVALUATION OF CLASSES OF BUILDINGS , 1999 .

[10]  Mervyn J. Kowalsky,et al.  THE LIMITATIONS AND PERFORMANCES OF DIFFERENT DISPLACEMENT BASED DESIGN METHODS , 2003 .

[11]  Julian J. Bommer,et al.  Inelastic spectra for displacement based seismic design , 2001 .

[12]  M. J. N. Priestley,et al.  DYNAMIC BEHAVIOUR OF REINFORCED CONCRETE FRAMES DESIGNED WITH DIRECT DISPLACEMENT-BASED DESIGN , 2005 .

[13]  Julian J. Bommer,et al.  Scaling of spectral displacement ordinates with damping ratios , 2005 .

[14]  Oral Büyüköztürk,et al.  Nonlinear analysis of reinforced concrete structures , 1977 .

[16]  Wilfred D. Iwan,et al.  The effective period and damping of a class of hysteretic structures , 1979 .

[17]  P. C. Jennings.  Periodic Response of a General Yielding Structure , 1964 .

[18]  L. Jacobsen.  Damping in Composite Structures , 1960 .

[19]  Eduardo Miranda,et al.  Evaluation of approximate methods to estimate maximum inelastic displacement demands , 2002 .