National Center for Research on Earthquake Engineering

About: National Center for Research on Earthquake Engineering is a nonprofit organization based out in Taipei, Taiwan. It is known for research contribution in the topics: Earthquake engineering & Earthquake shaking table. The organization has 435 authors who have published 621 publications receiving 11256 citations. The organization is also known as: NCREE.

Correlations between Vs and SPT-N by different borehole measurement methods: effect on seismic site classification

Abstract: The average shear wave velocity of the top 30 m of the subsurface profile (Vs30) is a critical parameter to characterize the seismic site class. Since Vs30 is a quantitative index and measurable by geophysical techniques, the use of Vs30 becomes popular and is widely used in practice. However, the Vs30 of a site may vary due to the different Vs measurement methods used. This could result in a different seismic site class and design force. To quantify the effect of measurement methods on Vs and seismic site classification. This study collected high quality geotechnical investigation reports with standard penetration test (SPT) N-values, and shear wave velocities measured by suspension logging, SCPT, down-hole test and cross-hole logging. The correlations between Vs and SPT-N by different methods were then built and compared. The results show that Vs by suspension logging is relatively high in comparison with those by SCPT and cross-hole logging. The effect on the site classification resulting from the different Vs measurement methods is then demonstrated with several examples.

Cyclic responses of three 2-story seismic concentrically braced frames

Abstract: Three full scale two-story steel concentrically braced frames (CBFs) were tested at the National Center for Research on Earthquake Engineering (NCREE) in Taipei. The specimen is a single bay with the braces arranged in a two-story X-brace configuration. The main differences among the three tests are the brace types (hollow structural or wide-flange section) and the design criteria adopted for the gusset plate connections. Results of these three tests confirm that the two-story X-shape steel CBFs all have rather good energy dissipation characteristics up to a story drift of about 0.03 radians under the cyclically increasing lateral displacements. Severe brace local buckling and out-of-plane displacements were observed during each test. Tests confirm that both the 2t-linear and 8t-elliptical designs of the gusset plate connection provide satisfactory ductility for the steel CBF. Hollow structural section (HSS) braces fractured at a story drift smaller than that found using wide flange sections. The nonlinear fine element method (FEM) program ABAQUS was used to simulate the responses of the specimen. The base shear versus the story drift relationships obtained from the tests and the FEM analytical results are quite agreeable in various levels of lateral frame displacement. The analytical results confirm that the severe out-of-plane buckling of the braces can be accurately simulated. FEM analyses also illustrate that the steel moment resisting frame takes about 40% story shear when the inter-story drift is greater than 0.02 radians.

A Major Hydrothermal Reservoir Underneath the Tatun Volcano Group of Taiwan: Clues from a Dense Linear Geophone Array

Abstract: A dense linear geophone array is deployed across the Tatun volcano group (TVG) at the northern tip of Taiwan, where more than 7 million residents live in the Taipei metropolis. The array is composed of 50 geophones with a station spacing of ~ 200 m in average, and it is designed for striking in the NW–SE direction to record the many earthquakes in eastern Taiwan, where the Philippine Sea plate subducted beneath the Eurasia plate. The detailed examination of felt earthquakes shows consistent P-wave delays are recorded at particular stations of the array. The further forward modeling indicates there is a low-velocity zone (LVZ) at depths between ~ 0.5 and ~ 2.5 km beneath the major fumarole sites. Combining this preliminary result with previous studies including clustering seismicity, volcanic earthquakes, low-resistivity zone, strong degassing processes and shallow velocity structures, we suggest that the LVZ might be associated with the major hydrothermal reservoir at the TVG. The identification of the hydrothermal reservoir by the LVZ not only implies a potential volcanic threat, such as phreatic eruptions, in the future, but also provides the possibility of sustainable geothermal resources for replacing traditional nuclear and fossil fuel power plants. Detailed images of the LVZ and other volcanic structures will be obtained soon when dense geophone arrays with more than 600 geophones are deployed from 2020 to 2022.

Active Control with Optical Fiber Sensors and Neural Networks. II: Experimental Verification

Abstract: Experimental results for a full-scale steel frame structure with a smart active control system under shaking-table testing are presented. To this end, a full-scale steel frame structure with the proposed control system is examined under earthquakes simulated by a 5 m × 5 m shaking table with several representative earthquakes arranged to assess the performance and robustness of the proposed control system. Signals detected from fiber Bragg grating sensors showed superior performance to conventional strain gauges in structure surveillance. Experimental data recorded during earthquake excitation, for structural strain, also demonstrated the improved performance of the proposed control system over the traditional active control. Experimental results demonstrated that the control system can be applied to buildings after the whole testing process.