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Showing 2 results for Seismic Response

M. Davoodii, M. K. Jafari, S. M. A. Sadrolddini,
Volume 11, Issue 1 (5-2013)

Spatial Variation of Earthquake Ground Motion (SVEGM) is clearly indicated in data recorded at dense seismographic arrays

The main purpose of this paper is to study the influence of SVEGM on the seismic response of large embankment dams. To this

end, the Masjed Soleyman embankment dam, constructed in Iran is selected as a numerical example. The spatially varying ground

motion time histories are generated using spectral representation method. According to this methodology, the generated time

histories are compatible with prescribed response spectra and reflect the wave passage and loss of coherence effects. To

investigate the sensitivity of the dam responses to the degree of incoherency, three different coherency models are used to simulate

spatially variable seismic ground motions. Finally, the seismic response of the dam under multi-support excitation is analyzed

and compared to that due to uniform ground motion. Also, the Newmark's method is used to estimate seismic-induced permanent

displacements of the embankment dam. The analysis results reveal that the dam responses can be sensitive to the assumed spatial

variation of ground motion along its base. As a general trend, it is concluded that the use of multi-support excitation, which is

more realistic assumption, results in lower acceleration and displacement responses than those due to uniform excitation.

Dongdong Zhang,
Volume 14, Issue 8 (12-2016)

This paper compares the seismic load of a 5MW wind turbine supported by a 100-m-high prestressed concrete tower calculated via time history analysis and response spectrum analysis using elastic acceleration spectrum provided by the China Aseismic Code for Buildings. With 5% damping ratio, the fixed-based Multi-degree of freedom model and Finite element model considering soil structure interaction are used for response spectrum analysis and time history analysis, respectively. The results indicated that the seismic load calculated by response spectrum analysis is significantly larger than the results associated with the time history analysis method. It implies that the seismic load determined from common building code procedures along with other loads for wind turbine foundation design is too conservative. Within this paper, the effects of damping ratio, horizontal acceleration amplitude, spring stiffness and damping coefficient of foundation on the seismic load of the prestressed concrete wind turbine tower are discussed. It is shown that the seismic load with mode damping ratio for the prestressed concrete wind turbine tower is not significant when compared with traditional tubular steel designs. The maximum moment demand at the base of the tower may be controlled by earthquake loading as the seismic fortification intensity lever is more than seven. The foundation spring stiffness has a immensely impact on the base bending moment and the natural frequency. Finally, seismic load should be considered in more detail when designing wind turbines that are supported by concrete towers, particularly for turbine’s over 100-m tall and located in seismically active zones.

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