Improved ASCE/SEI 7-10 Ground-Motion Scaling Procedure for Nonlinear Analysis of Buildings

ABSTRACT

An improved ASCE/SEI 7–10 ground-motion scaling procedure for three-dimensional (3D) response history analysis (RHA) of buildings is presented. In this procedure, different scale factors for two horizontal components of the ground motion are used, and their spectral shapes are considered in ground-motion selection stage. The accuracy of the improved procedure is evaluated by utilizing 3D models of nine asymmetric-plan buildings. It is demonstrated that the improved procedure provides on average 15% conservative estimates of engineering demand parameters while the original version underestimates them on average 29%. Thus, the improved ground-motion selection and scaling procedure is found to be appropriate for nonlinear RHAs of multi-story plan-asymmetric buildings.

KEYWORDS:

• Response History Analysis
• Dynamic Analysis
• Ground-Motion Scaling
• Asymmetric-Plan Building
• Performance-Based Design
• Plan Irregularity

Nomenclature

The following symbols and abbreviations are used in this paper:

$A_{mx}$    median value of $S{F}_{1x}\cdot A_x$

$A_{my}$    median value of $S{F}_{1y}\cdot A_y$

${\hat{A}}_x$    target pseudo-acceleration spectrum in x-direction

${\hat{\mathbf{A}}}_{\mathbf{x}}$    vector of spectral values ${\hat{A}}_x$

$A_x$    5%-damped response spectrum for x-component

${\mathbf{A}}_{\mathbf{x}}$    vector of spectral values $A_x$

${\hat{A}}_y$    target pseudo-acceleration spectra for y-direction

${\hat{\mathbf{A}}}_{\mathbf{y}}$    vector of spectral values ${\hat{A}}_y$

$A_y$    5%-damped response spectrum for y-component

${\mathbf{A}}_{\mathbf{y}}$    vector of spectral values $A_y$

$k$    number of ground-motion records in a set

L    plan asymmetric about x- and y-axes

$M$    number of sets of $k$ records

$N$    total number of vibration modes considered

R    quasi-rectangular plan

R_JB    Joyner–Boore distance

$S{F}_x$    final scale factor for $x$ horizontal component of record

$S{F}_y$    final scale factor for $y$ horizontal component of record

$S{F}_{1x}$    first scale factor for $x$ horizontal component of record

$S{F}_{1y}$    first scale factor for $y$ horizontal component of record

$S{F}_{2x}$    second scale factor for $x$ horizontal component of record

$S{F}_{2y}$    second scale factor for $y$ horizontal component of record

T    plan symmetric about y-axis

$T_n$    vibration period

$x_{50}$    median of a log-normal distribution

$\beta$    torsional irregularity factor

${\mathrm{\Delta }}_{\mathrm{m}\mathrm{a}\mathrm{x}}$    maximum story drift

${\mathrm{\Delta }}_{\mathrm{a}\mathrm{v}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{g}\mathrm{e}}$    average story drift

${\epsilon }_x$    maximum normalized difference for $x$ horizontal component of record

${\epsilon }_y$    maximum normalized difference for $y$ horizontal component of record

${\theta }_p$    plastic rotation

${\theta }_y$    yield rotation

$\mu$    mean of a log-normal distribution

$\hat{\mu }$    geometric mean of a log-normal distribution

Acknowledgments

The authors would like to thank Charlie Kircher, Kishor Jaiswal, Brad Aagaard, Jamie Steidl, and three anonymous reviewers for their critical reviews, constructive comments, and editorial suggestions, which improved technical content and presentation of this paper.

Data and resources

Ground-motion records used in this study are available from the University of California, Berkeley Pacific Earthquake Engineering Research Center Ground-Motion Database at https://ngawest2.berkeley.edu/(last accessed on May 2018). The ground-motion selection and scaling procedure proposed herein are available as a MatLAB® function. This function and finite element models developed for this study are available from the authors upon request.