常熟地震台VS垂直摆试运行

通过对正在试运行的VS垂直摆观测资料做基本的可靠性、内在精度、地震响应等分析,从而评介该仪器的观测能力,确认它在常熟地震台形变观测中的监测地位。     

非线性Rossby波动特征的进一步探讨

在一定的假定下,利用自然坐标系对正压非线性Rossby波的特征作了进一步探讨,指出控制Rossby波动过程的本质方程是摆型方程及类似于Sine—Gordon方程的关系式,得到了波动过程中复杂的质点振动轨迹和非线性振荡的周期;给出了定常Rossby波的几种复杂流型,证明了非线性Rossby波的位相传播和能量传播是沿着流线进行的。这些结果对深入认识大气内部动力过程和解释某些观测现象具有一定意义。     

Spheroidal Oscillations in the Earth Excited by the Wenchuan Earthquake

Based on the digital observational data from pendulum tilt-meters and water tube tilt-meters, the spheroidal free oscillations of the Earth, excited by the M_S8.0 Wenchuan earthquake of May 12, 2008, were obtained using the method of power spectral density estimation without any calculation to erase solid tides. The result matches well with the PREM results. Compared to the theoretical free oscillation from the PREM model, all relative errors are concentrated on 0.1% except for _0S_7, whose relative error is greater than 0.3%. This research provides a new method to determine the spheroidal modes of Earth's free oscillations from observations of the pendulum tilt-meter and water tube tilt-meter, which may be useful in the future study of the Earth's free oscillations.     

汤原4.7级地震前后依兰台地倾斜异常机制的研究

本文介绍了１９９０年５月黑龙江省汤原４．７地震前后依兰台地倾斜固体潮汐畸变曲型图象的形态基本特征。     

Behaviour of the double concave Friction Pendulum bearing

The double concave Friction Pendulum (DCFP) bearing is an adaptation of the well‐known single concave Friction Pendulum bearing. The principal benefit of the DCFP bearing is its capacity to accommodate substantially larger displacements compared to a traditional FP bearing of identical plan dimensions. Moreover, there is the capability to use sliding surfaces with varying radii of curvature and coefficients of friction, offering the designer greater flexibility to optimize performance. This paper describes the principles of operation of the bearing and presents the development of the force–displacement relationship based on considerations of equilibrium. The theoretical force–displacement relationship is then verified through characterization testing of bearings with sliding surfaces having the same and then different radii of curvature and coefficients of friction. Lastly, some practical considerations for analysis and design of DCFP bearings are presented. Copyright © 2006 John Wiley & Sons, Ltd.     

Spherical sliding isolation bearings with adaptive behavior: Theory

The principles of operation and force–displacement relationships of three novel spherical sliding isolation bearings are developed in this paper. These bearings are completely passive devices, yet exhibit adaptive stiffness and adaptive damping. That is, the stiffness and damping change to predictable values at calculable and controllable displacement amplitudes. The primary benefit of adaptive behavior is that a given isolation system can be separately optimized for multiple performance objectives and/or multiple levels of ground shaking. With the devices presented here, this is accomplished using technology that is inherently no more complex than what is currently used by the civil engineering profession. The internal construction consists of various concave surfaces and behavior is dictated by the different combinations of surfaces upon which sliding can occur over the course of motion. As the surfaces upon which sliding occurs change, the stiffness and effective friction change accordingly. A methodology is presented for determining which surfaces are active at any given time based on the effective radius of curvature, coefficient of friction and displacement capacity of each sliding surface. The force–displacement relationships and relevant parameters of interest are subsequently derived based on the first principles. Copyright © 2007 John Wiley & Sons, Ltd.     

Response of base‐isolated nuclear structures for design and beyond‐design basis earthquake shaking

The American Society of Civil Engineers (ASCE) 43‐05 presents two performance objectives for the design of nuclear structures, systems and components in nuclear facilities: (1) 1% probability of unacceptable performance for 100% design basis earthquake (DBE) shaking and (2) 10% probability of unacceptable performance for 150% DBE shaking. To aid in the revision of the ASCE 4‐98 procedures for the analysis and design of base‐isolated nuclear power plants and meet the intent of ASCE 43‐05, a series of nonlinear response‐history analyses was performed to study the impact of the variability in both earthquake ground motion and mechanical properties of isolation systems on the seismic responses of base‐isolated nuclear power plants. Computations were performed for three representative sites (rock and soil sites in the Central and Eastern United States and a rock site in the Western United States) and three types of isolators (lead rubber, Friction Pendulum and low‐damping rubber bearings) using realistic mechanical properties for the isolators. Estimates were made of (1) the ratio of the 99th percentile (90th percentile) response of isolation systems computed using a distribution of spectral demands and distributions of isolator mechanical properties to the median response of isolation systems computed using best‐estimate properties and 100% (150%) spectrum‐compatible DBE ground motions; (2) the number of sets of three‐component ground motions to be used for response‐history analysis to develop a reliable estimate of the median response of isolation systems. The results of this study provide the technical basis for the revision of ASCE Standard 4‐98. Copyright © 2012 John Wiley & Sons, Ltd.