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.

Simplified seismic analysis of asymmetric building systems

Abstract: The paper reviews the uncoupled modal response history analysis (UMRHA) and modal pushover analysis (MPA) procedure in the analysis of asymmetric structures. From the pushover curves in ADRS format, showing the relationships of base shear versus roof translation and base torque versus roof rotation, a bifurcating characteristic of the pushover curves of an asymmetric structure is observed. A two-degree-of-freedom (2DOF) modal stick is constructed using lump mass eccentrically placed at the end of beam which is connected with the column by a rotational spring. By converting the equation of motion of a whole structure into 2DOF modal equations, all of the elastic properties in the 2DOF modal sticks can be determined accurately. A mathematical proof is carried out to demonstrate that the 2DOF modal stick is consistent with the single-degree-of-freedom (SDOF) modal stick at elastic state. The bifurcating characteristic of modal pushover curves and the interaction of modal translation and rotation can be considered rationally by this 2DOF modal stick. In order to verify the effectiveness of this proposed 2DOF modal stick, a two-storey asymmetric building structure was analysed by the UMRHA procedure incorporating this novel 2DOF modal sticks (2DMPA) and conventional SDOF modal sticks (SDMPA), respectively. The analytical results are compared with those obtained by nonlinear response history analysis (RHA). It is illustrated that the accuracy of the rotational response histories obtained by 2DMPA is much better than those obtained by SDMPA. Consequently, the estimations of translational response histories on flexible side (FS) and stiff side (SS) of the building structure are also improved.

Cyclic test of a coupled steel plate shear wall substructure

Abstract: SUMMARY Coupled steel plate shear wall (C-SPSW) consists of two or more steel plate shear walls interconnected by coupling beams at the floor levels. In this study, a six-story C-SPSW prototype building was designed. A 40% scale C-SPSW specimen, which is representative of the bottom two-and-half-story substructure of the prototype, was cyclically tested using Multi-Axial Testing System at the National Center for Research on Earthquake Engineering in 2009. In addition to a constant vertical force representing the gravity load effects, cyclic increasing displacements and the corresponding overturning moments transmitted from the upper stories were computed online and simultaneously applied on the substructural specimen. This paper firstly introduces the designs of the prototype C-SPSW and the test specimen. Then, the test results and the numerical simulation are discussed in detail. Test results confirm the effectiveness of the proposed column capacity design method, which aims at limiting the plastic hinge formation within the bottom quarter height of the bottom column. Test and analytical results suggest that the coupling beam rotational demands can be estimated as the design story drifts when the formation of desirable plastic mechanism of the C-SPSW is expected. Copyright © 2011 John Wiley & Sons, Ltd.

Dynamic Response of Equipment in Structures with Sliding Support

Abstract: The dynamic behaviour of a single degree-of-freedom (DOF) equipment mounted on a sliding primary structures subjected to harmonic and earthquake ground motions is studied numerically. To deal with the discontinuity nature of sliding structural systems, in this work the fictitious spring model is adopted. With the problem formulated in a state space form, an incremental numerical scheme capable of dealing with multi-DOF sliding structural systems is proposed for solving the time history responses. Numerical examples excited by harmonic and real earthquake ground motions are considered in order to study the following three effects: (1) the variation of the frictional coefficient of the sliding support, (2) subharmonic resonance and (3) effect of tuning (i.e. when the frequency of the equipment is coincident with or close to the fundamental frequency of the primary structure) on the mounted equipment. The dynamic characteristics of the mounted equipment are highlighted in the analysis of the numerical examples.

On the influence of site conditions and earthquake magnitude on ground-motion within-earthquake correlation: analysis of PGA data from TSMIP (Taiwan) network

Abstract: We analysed the within-earthquake correlation of ground motion using the strong-motion records accumulated by the TSMIP (Taiwan Strong Motion Instrumentation Program) network in Taiwan during 1993–2009. Two ground-motion prediction equations, which were recently developed for peak ground acceleration (PGA) in the region and based on moment and local magnitude and hypocentral distance, were used for the calculation and analysis of ground-motion residuals. We also used the database containing shear-wave velocity data averaged for the top 30 m of the soil column (Vs30) for the TSMIP stations. We showed that the within-earthquake correlation may vary significantly depending on site classes, gross geological features of the area, and magnitude of earthquakes, records of which dominate the analysed dataset. On the one hand, there is a prominent correspondence between the within-earthquake correlation of PGA residuals and spatial correlation of Vs30 values, which was estimated for particular geological structures (e.g., sedimentary filled basins and large plain areas). On the other hand, the high level of ground-motion correlation (or significant non-random component of residuals) may be caused by the joint influence of soft surface soil and thick sediments and by the path or azimuthal effects. The point-source approximation of extended fault and neglected hanging- and foot-wall effects may also result in non-random residuals. The application of empirical correction factors, which consider the magnitude of earthquakes, source-to-site distance and Vs30 value for given stations, allows for the effective reduction in the level of within-earthquake correlation, as well as the within-earthquake standard deviation. The results of the analysis may be used in practical estimates of seismic hazard, damage and loss for spatially distributed structures (portfolios, lifelines) in Taiwan, as well in other regions with similar geological characteristics.