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Effect of damping and yielding on the seismic response of 3D steel buildings with PMRF.

Reyes-Salazar A, Haldar A, Rodelo-López RE, Bojórquez E - ScientificWorldJournal (2014)

Bottom Line: The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion.It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation.Much more research is needed to reach more general conclusions.

View Article: PubMed Central - PubMed

Affiliation: Facultad de Ingeniería, Universidad Autónoma de Sinaloa, Ciudad Universitaria, 80040 Culiacán, SIN, Mexico.

ABSTRACT
The effect of viscous damping and yielding, on the reduction of the seismic responses of steel buildings modeled as three-dimensional (3D) complex multidegree of freedom (MDOF) systems, is studied. The reduction produced by damping may be larger or smaller than that of yielding. This reduction can significantly vary from one structural idealization to another and is smaller for global than for local response parameters, which in turn depends on the particular local response parameter. The uncertainty in the estimation is significantly larger for local response parameter and decreases as damping increases. The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion. It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation. Moreover, the effect of yielding should be explicitly calculated by using complex 3D MDOF models instead of estimating it in terms of equivalent viscous damping. The findings of this paper are for the particular models used in the study. Much more research is needed to reach more general conclusions.

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Related in: MedlinePlus

Elastic response spectra for scaled earthquakes.
© Copyright Policy - open-access
Related In: Results  -  Collection


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fig3: Elastic response spectra for scaled earthquakes.

Mentions: Dynamic responses of a structure excited by different earthquake time histories, even when they are normalized in terms of Sa(T1) or in terms of the peak ground acceleration, are expected to be different, reflecting their different frequency contents. Thus, evaluating structural responses excited by an earthquake may not reflect the behavior properly. To study the responses of the models comprehensively and to make meaningful conclusions, they are excited by twenty recorded earthquake motions in time domain with different frequency contents, recorded at different locations. The models are simultaneously subjected to the action of the three components of the earthquake records for the case of three-dimensional and SDOF models, and to one horizontal component at a time and the vertical component, for the case of the plane models. As stated earlier, the earthquake records are scaled in terms of spectral acceleration in the fundamental mode of vibration of the structure (Sa(T1)) first for elastic behavior and then for a significant level of deformation. The characteristics of these earthquake time histories are given in Table 3. They were selected to cover a wide range of excitation frequency content, to have PGAs close to or larger than 0.20 g, and to have a strong phase duration of at least 30 seconds with an acceleration close to or larger than 0.15 g. In the table, the symbols T, EP, DE, and MA denote the predominant period, the distance to the epicenter, and the depth and the magnitude of the earthquake, respectively. The peak ground acceleration, velocity, and displacement (PGA, PGV, and PGD) are also observed. As shown in the table, the predominant periods of the earthquakes for the N-S component vary from 0.12 to 0.88 sec. The predominant period for each earthquake is defined as the period where the largest peak in the elastic response spectrum occurs, in terms of pseudoaccelerations. The response spectra for the N-S component for 5% damping for a significant level of deformation are given in Figure 3. The earthquake time histories were obtained from the data sets of the National Strong Motion Program (NSMP) of the United States Geological Surveys (USGS). Additional information on these earthquakes can be obtained from this database.


Effect of damping and yielding on the seismic response of 3D steel buildings with PMRF.

Reyes-Salazar A, Haldar A, Rodelo-López RE, Bojórquez E - ScientificWorldJournal (2014)

Elastic response spectra for scaled earthquakes.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4109077&req=5

fig3: Elastic response spectra for scaled earthquakes.
Mentions: Dynamic responses of a structure excited by different earthquake time histories, even when they are normalized in terms of Sa(T1) or in terms of the peak ground acceleration, are expected to be different, reflecting their different frequency contents. Thus, evaluating structural responses excited by an earthquake may not reflect the behavior properly. To study the responses of the models comprehensively and to make meaningful conclusions, they are excited by twenty recorded earthquake motions in time domain with different frequency contents, recorded at different locations. The models are simultaneously subjected to the action of the three components of the earthquake records for the case of three-dimensional and SDOF models, and to one horizontal component at a time and the vertical component, for the case of the plane models. As stated earlier, the earthquake records are scaled in terms of spectral acceleration in the fundamental mode of vibration of the structure (Sa(T1)) first for elastic behavior and then for a significant level of deformation. The characteristics of these earthquake time histories are given in Table 3. They were selected to cover a wide range of excitation frequency content, to have PGAs close to or larger than 0.20 g, and to have a strong phase duration of at least 30 seconds with an acceleration close to or larger than 0.15 g. In the table, the symbols T, EP, DE, and MA denote the predominant period, the distance to the epicenter, and the depth and the magnitude of the earthquake, respectively. The peak ground acceleration, velocity, and displacement (PGA, PGV, and PGD) are also observed. As shown in the table, the predominant periods of the earthquakes for the N-S component vary from 0.12 to 0.88 sec. The predominant period for each earthquake is defined as the period where the largest peak in the elastic response spectrum occurs, in terms of pseudoaccelerations. The response spectra for the N-S component for 5% damping for a significant level of deformation are given in Figure 3. The earthquake time histories were obtained from the data sets of the National Strong Motion Program (NSMP) of the United States Geological Surveys (USGS). Additional information on these earthquakes can be obtained from this database.

Bottom Line: The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion.It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation.Much more research is needed to reach more general conclusions.

View Article: PubMed Central - PubMed

Affiliation: Facultad de Ingeniería, Universidad Autónoma de Sinaloa, Ciudad Universitaria, 80040 Culiacán, SIN, Mexico.

ABSTRACT
The effect of viscous damping and yielding, on the reduction of the seismic responses of steel buildings modeled as three-dimensional (3D) complex multidegree of freedom (MDOF) systems, is studied. The reduction produced by damping may be larger or smaller than that of yielding. This reduction can significantly vary from one structural idealization to another and is smaller for global than for local response parameters, which in turn depends on the particular local response parameter. The uncertainty in the estimation is significantly larger for local response parameter and decreases as damping increases. The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion. It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation. Moreover, the effect of yielding should be explicitly calculated by using complex 3D MDOF models instead of estimating it in terms of equivalent viscous damping. The findings of this paper are for the particular models used in the study. Much more research is needed to reach more general conclusions.

Show MeSH
Related in: MedlinePlus