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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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Elevation, plan, and element location for Models SC1 and SC2.
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Related In: Results  -  Collection


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fig1: Elevation, plan, and element location for Models SC1 and SC2.

Mentions: The elevations of the models are given in Figures 1(a) and 1(d) and their plans are given in Figures 1(b) and 1(e), respectively. They will be denoted hereafter by Models SC1 and SC2, respectively. The fundamental periods of Model SC1 are estimated to be 1.03, 0.99, and 0.07 sec., in the N-S (horizontal), W-E (horizontal), and Z (vertical) directions, respectively. The corresponding values for Model SC2 are 2.22, 2.11, and 0.16 sec. The 10-level building has a single-level basement. The columns of the PMRF of Model SC1 are fixed at the base while those of Model SC2 are pinned, as considered in the FEMA report [31]. In all these frames, the columns are made of steel Grade-50 and the girders are of A36 steel. For both models, the columns in the gravity frames (GF) are considered to be pinned at the base. All the columns in the PMRF bend about the strong axis and the strong axes of the gravity columns are oriented in the N-S direction, as indicated in Figures 1(b) and 1(e). The particular elements to study the response in terms of local responses parameters are given in Figures 1(c) and 1(f) for Models SC1 and SC2, respectively. In these figures, the PMRF are represented by continuous lines while the interior GF are represented by dashed lines. For Model SC2, the PMRF meet at a corner. In this case, the beam-to-column connections are considered to be pinned to eliminate weak-axis bending (Figure 1(e)). As it can be seen, the buildings are essentially symmetrical in plan; thus no significant torsional moments are expected to occur. Sizes of beams and columns, as reported, are given in Table 1 for the two models. The designs of the PMRF in the two orthogonal directions were practically the same. Additional information for the models can be obtained from the FEMA report [31].


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)

Elevation, plan, and element location for Models SC1 and SC2.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: Elevation, plan, and element location for Models SC1 and SC2.
Mentions: The elevations of the models are given in Figures 1(a) and 1(d) and their plans are given in Figures 1(b) and 1(e), respectively. They will be denoted hereafter by Models SC1 and SC2, respectively. The fundamental periods of Model SC1 are estimated to be 1.03, 0.99, and 0.07 sec., in the N-S (horizontal), W-E (horizontal), and Z (vertical) directions, respectively. The corresponding values for Model SC2 are 2.22, 2.11, and 0.16 sec. The 10-level building has a single-level basement. The columns of the PMRF of Model SC1 are fixed at the base while those of Model SC2 are pinned, as considered in the FEMA report [31]. In all these frames, the columns are made of steel Grade-50 and the girders are of A36 steel. For both models, the columns in the gravity frames (GF) are considered to be pinned at the base. All the columns in the PMRF bend about the strong axis and the strong axes of the gravity columns are oriented in the N-S direction, as indicated in Figures 1(b) and 1(e). The particular elements to study the response in terms of local responses parameters are given in Figures 1(c) and 1(f) for Models SC1 and SC2, respectively. In these figures, the PMRF are represented by continuous lines while the interior GF are represented by dashed lines. For Model SC2, the PMRF meet at a corner. In this case, the beam-to-column connections are considered to be pinned to eliminate weak-axis bending (Figure 1(e)). As it can be seen, the buildings are essentially symmetrical in plan; thus no significant torsional moments are expected to occur. Sizes of beams and columns, as reported, are given in Table 1 for the two models. The designs of the PMRF in the two orthogonal directions were practically the same. Additional information for the models can be obtained from the FEMA report [31].

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