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Lin P.-Y.,National Center for Research on Earthquake Engineering
International Journal of Automation and Smart Technology | Year: 2011

Because of Taiwan's unique geographical environment, earthquake disasters occur frequently in Taiwan. The Central Weather Bureau collated earthquake data from between 1901 and 2006 (Central Weather Bureau, 2007) and found that 97 earthquakes had occurred, of which, 52 resulted in casualties. The 921 Chichi Earthquake had the most profound impact. Because earthquakes have instant destructive power and current scientific technologies cannot provide precise early warnings in advance, earthquake prevention is crucial. The earthquake early warning system can provide seconds to tens of seconds of warning time before an earthquake strikes. This paper introduces the earthquake early warning system build by Taiwan National Center for Research on Earthquake Engineering and a practice case happened in Yilan City, Taiwan. © 2011 International Journal of Automation and Smart Technology.

Chou C.-C.,National Taiwan University | Chou C.-C.,National Center for Research on Earthquake Engineering | Chen J.-H.,National Chiao Tung University
Earthquake Engineering and Structural Dynamics | Year: 2010

Gaps between beam-to-column interfaces in a post-tensioned (PT) self-centering frame with more than one column are constrained by columns, which causes beam compression force different from the applied PT force. This study proposes an analytical method for evaluating column bending stiffness and beam compression force by modeling column deformation according to gap-openings at all stories. The predicted compression forces in the beams are validated by a cyclic analysis of a three-story PT frame and by cyclic tests of a full-scale, two-bay by first-story PT frame, which represents a substructure of the three-story PT frame. The proposed method shows that compared with the strand tensile force, the beam compression force is increased at the 1st story but is decreased at the 2nd and 3rd stories due to column deformation compatibility. The PT frame tests show that the proposed method reasonably predicts beam compression force and strand force and that the beam compression force is 2 and 60% larger than the strand force with respect to a minor restraint and a pin-supported boundary condition, respectively, at the tops of the columns. Therefore, the earlier method using a pin-supported boundary condition at upper story columns represents an upper bound of the effect and is shown to be overly conservative for cases where a structure responds primarily in its first mode. The proposed method allows for more accurate prediction of the column restraint effects for structures that respond in a pre-determined mode shape which is more typical of low and mid-rise structures. © 2009 John Wiley & Sons, Ltd.

Chou C.-C.,National Taiwan University | Chou C.-C.,National Center for Research on Earthquake Engineering | Chen S.-Y.,National Chiao Tung University
Engineering Structures | Year: 2010

This study presents the experimental and finite element analysis results of a proposed steel buckling-restrained brace (BRB). The proposed BRB has two components: (1) a steel core plate that carries all axial forces during tension and compression, and (2) two identical restraining members that sandwich the core plate with fully tensioned high-strength A490 bolts to prevent core buckling. Instead of using unbonded material, a small air gap is provided between the core plate and the restraining members to allow for lateral expansion of the core plate under compression. Since two restraining members can be disassembled easily by removing the bolts, a damaged steel core can be replaced after a large earthquake. Thus, manufacturing new restraining members is not required. Four BRB subassemblages were tested to investigate the inelastic deformation capabilities and verify the stability predictions for the braces. Test results indicate that three BRBs with sufficient flexural rigidity of the restraining member develop (1) stable hysteretic responses up to core axial strains of 2.1%-2.6%, (2) maximum compressive loads of 1724-1951 kN (1.4-1.6 times the actual yield load), and (3) a cumulative plastic ductility that is much higher than that specified in AISC seismic provisions (2005). One BRB, intentionally designed with inadequate flexural rigidity of the restraining member, experienced global buckling as predicted. Nonlinear finite element analysis was conducted for each BRB for a correlation study. The objective of the analysis was to conduct a parametric study for different BRBs to further verify the effects of restraining member size, number of bolts, core plate length and cross-sectional area on buckling load evaluation. The design procedure for the sandwiched BRB was provided based on test and finite element analysis results. © 2010 Elsevier Ltd.

Lin J.-L.,National Center for Research on Earthquake Engineering | Tsai K.-C.,National Taiwan University
Earthquake Spectra | Year: 2013

For practicing engineers, knowledge of the characteristics of supplemental damping in buildings is essential to understand the resultant effects of added damping. Characterizing the overall system parameters representing the amount and the plan-wise distribution of the supplemental damping in a single-story asymmetrical building is straightforward. However, this becomes a difficult task for multistory asymmetrical buildings. For this reason, this paper first develops the effective one-story building (EOSB), which retains the characteristics of the two dominant vibration modes of the original nonproportionally damped multistory asymmetrical building. By using the EOSB, it becomes convenient to characterize the supplemental damping in the original multistory asymmetrical building. The effectiveness of this approach is verified by using three numerical examples, which include one one-story, three eight-story, and one 20-story asymmetrical buildings. Next, the relationships between the roof displacements of the original building and those of the EOSB are established. This enables the application of the response spectra constructed from the EOSBs to estimate the peak roof displacements of the original multistory asymmetrical building. © 2013, Earthquake Engineering Research Institute.

Ko Y.-Y.,National Center for Research on Earthquake Engineering | Chen C.-H.,National Taiwan University
Earthquake Engineering and Structural Dynamics | Year: 2010

In the conventional structural seismic analysis, the rigid base model is usually adopted without considering the flexibility of the ground, leading to inaccurate estimation of the vibration characteristics and the seismic response of the structure. In 2007, several in situ tests were conducted by the National Center for Research on Earthquake Engineering (NCREE) on the school buildings in the Guanmiao Elementary School in Tainan, Taiwan. For the study of soil-structure interaction (SSI) effects, the forced vibration test (FVT) was performed, and the deformation of the foundation system was measured during the pushover test. In this paper, the results of these in situ tests are presented and discussed, and the finite element models of the school buildings were generated for the simulation of the FVT and for the pushover analysis in order to investigate the difference between the rigid base model and the flexible base model. Results show that the mechanical properties of the structure and the foundation could be demonstrated in these in situ tests. Additionally, the introduction of the flexibility of the foundation has a considerable influence on the results of structural analysis. © 2009 John Wiley & Sons, Ltd.

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