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In order to obtain the seismic dynamic characteristics of a shallow-bias tunnel with a small space, a series of large-scale shaking table model tests were carried out. The key technology of the test is introduced in detail, for example, similar ratios of model, test equipment, testing model box, testing model, sensor arrangement, seismic waves, and testing system. The results show that the first predominant frequency is similar between measuring points. However, the second predominant frequency is highly different between measuring points. The first and second predominant frequencies gradually decrease with the increasing of input PGA. The rock stratum can shield seismic wave in the high frequency band. The research results provide reference for similar tunnels. [ABSTRACT FROM AUTHOR]

Seismic demands of a curtain wall (CW) relate to the floor response of the main structure. These demands include both acceleration and deformation. Floor capacity spectrum combines these demands into one acceleration-displacement response spectrum (ADRS) representing the CW as a single degree of freedom system. The in-plane (IP) load-displacement relationship can be transformed to the acceleration-displacement format (capacity curve) of the ADRS. The intersection of the capacity curve and the ADRS is the performance point (PP) of the CW system. Another way to determine the PP is through the floor response analysis of the main structure where the pairs of acceleration and displacement demands form the demand PPs. In shaking table testing of the CW system, the two coordinates of the PP can be simulated by applying the IP deformation with a specially designed loading frame, then exciting the test specimen by the shaking table in the out-of-plane direction. PPs are accurately reproduced and the seismic performance of the CW system is evaluated. The applicability and reliability of this novel shaking table test method are discussed in this paper. [ABSTRACT FROM AUTHOR]

SUMMARY Vibration isolation is well recognized as an effective mitigation strategy for acceleration-sensitive equipment subjected to earthquake. In the present paper, an equipment isolation system with nonlinear hysteretic behaviour is proposed and a methodology for the optimal design is developed. An integrable constitutive model, derived from the mathematical Duhem hysteresis operator, is adopted for the isolation system. The optimization procedure is defined through a dual-criteria approach that involves a transmissibility criterion combined with an energy performance criterion: the former consists in limiting the absolute acceleration of the isolated equipment below an allowable threshold value; the latter, in maximizing the ratio between the energy dissipation due to hysteresis and the input energy to reduce the isolator displacements. The seismic effectiveness of the nonlinear hysteretic isolation system is numerically investigated under natural accelerograms with different frequency content and increasing levels of excitation. Both ground-mounted and floor-mounted equipment items are considered in the analyses; in the second case, the dynamic interaction between the equipment and its supporting structure is taken into account in the design of the isolation system, and its effects on the isolation performance and the structural response are discussed. Comparisons in terms of effectiveness and robustness with a linear isolation system with viscoelastic behaviour are eventually provided. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Displacement measurements are useful information for various engineering applications such as structural health monitoring (SHM), earthquake engineering and system identification. Most existing displacement measurement methods are costly, labor-intensive, and have difficulties particularly when applying to full-scale civil structures because the methods require stationary reference points. Indirect estimation methods converting acceleration to displacement can be a good alternative as acceleration transducers are generally cost-effective, easy to install, and have low noise. However, the application of acceleration-based methods to full-scale civil structures such as long span bridges is challenging due to the need to install cables to connect the sensors to a base station. This article proposes a low-cost wireless displacement measurement system using acceleration. Developed with smart sensors that are low-cost, wireless, and capable of on-board computation, the wireless displacement measurement system has significant potential to impact many applications that need displacement information at multiple locations of a structure. The system implements an FIR-filter type displacement estimation algorithm that can remove low frequency drifts typically caused by numerical integration of discrete acceleration signals. To verify the accuracy and feasibility of the proposed system, laboratory tests are carried out using a shaking table and on a three storey shear building model, experimentally confirming the effectiveness of the proposed system. [ABSTRACT FROM AUTHOR]

Most strong-motion data processing involves acausal low-cut filtering, which requires the addition of sometimes lengthy zero pads to the data. These padded sections are commonly removed by organizations supplying data, but this can lead to incompatibilities in measures of ground motion derived in the usual way from the padded and the pad-stripped data. One way around this is to use the correct initial conditions in the pad-stripped time series when computing displacements, velocities, and linear oscillator response. Another way of ensuring compatibility is to use postprocessing of the pad-stripped acceleration time series. Using 4071 horizontal and vertical acceleration time series from the Turkish strong-motion database, we show that the procedures used by two organizations-ITACA (ITalian ACcelerometric Archive) and PEER NGA (Pacific Earthquake Engineering Research Center-Next Generation Attenuation)-lead to little bias and distortion of derived seismic-intensity measures. [ABSTRACT FROM AUTHOR]

The article focuses on a uniaxial electrodynamic shake table named CUSHAKE, which was developed and tested at the Cukurova University's Civil Engineering Department in Adana, Turkey. It says that the earthquake simulation table's main frame is made of steel beams and has servo, four bearings, and two rails. It adds that the table can be controlled by a personal computer using DEPSIM software, can handle a test load up to 1000 kilograms (kg), and costs 45,000 U.S. dollars.

The article focuses on the history of the contribution of shaking tables in the advancements in earthquake engineering. It states that one of the significations of experimental device shaking tables in the earthquake engineering, is that they replicate the true nature of the earthquake input. It mentions that these devices apply the ground motion to the base of a structure and induce the inertia forces in the element of its mass. It adds that the Froude and the Cauchy numbers for the model and prototype must be equal to the ratio of gravity and the dynamic inertia forces. Meanwhile, it says that the first laboratory experiments regarding the impact of earthquakes on the structural models were conducted by Englishman John Milne and Japanese Fusakichi Omori in Japan in 1890.

The article offers information on the Sigma cableless seismic data acquisition system from International Seismic Co. (iSeis).