| Title |
Evaluation of Equivalent-Static Floor Acceleration for Seismic Design of Non-Structural Elements |
| Authors |
Jun, Su-Chan ; Lee, Cheol-Ho ; Bae, Chang-Jun ; Kim, Sung-Yong |
| DOI |
https://doi.org/10.5659/JAIK_SC.2020.36.3.121 |
| Keywords |
Seismic Design; Non-Structural Elements; Equivalent Static Approach; Dynamic Method; Floor Acceleration; Torsional Amplification |
| Abstract |
In this paper, the ASCE 7 equivalent static approach for seismic design of non-structural elements is critically evaluated based on the
measured floor acceleration data, theory of structural dynamics, and linear/nonlinear dynamic analysis of three-dimensional building models.
The analysis of this study on the up-to-date database of the instrumented buildings in California clearly reveals that the measured database
does not well corroborate the magnitude and the profile of the floor acceleration as proposed by ASCE 7. The basic flaws in the equivalent
static approach are illustrated using elementary structural dynamics. Based on the linear and nonlinear dynamic analyses of three-dimensional
case study buildings, it is shown that the magnitude and distribution of the PFA (peak floor acceleration) can significantly be affected by the
supporting structural characteristics such as fundamental period, higher modes, structural nonlinearity, and torsional irregularity. In general, the
equivalent static approach yields more conservative acceleration demand as building period becomes longer, and the PFA distribution in
long-period buildings tend to become constant along the building height due to the higher mode effect. Structural nonlinearity was generally
shown to reduce floor acceleration because of its period-lengthening effect. Torsional floor amplification as high as 250% was observed in
the building model of significant torsional irregularity, indicating the need for inclusion of the torsional amplification to the equivalent static
approach when building torsion is severe. All these results lead to the conclusion that, if permitted, dynamic methods which can account for
supporting structural characteristics, should be preferred for rational seismic design of non-structural elements. |