我所2016年发表论文欣赏-第二十二期

地球所研究生会 · 公众号 · · 2017-06-05 16:14

正文

题目

Complex complete quadratic combination method for damped system with repeated eigenvalues

作者

Yu Ruifang 1, Zhou Xiyuan 2 and Abduwaris Abduwahit 3

发表刊物

《EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION 》

摘要

A new response-spectrum mode superposition method, entirely in real value form, is developed to analyze the maximum structural response under earthquake ground motion for generally damped linear systems with repeated eigenvalues and defective eigenvectors. This algorithm has clear physical concepts and is similar to the complex complete quadratic
combination (CCQC) method previously established. Since it can consider the effect of repeated eigenvalues, it is called the CCQC-R method, in which the correlation coeffi cients of high-order modal responses are enclosed in addition to the correlation coeffi cients in the normal CCQC method. As a result, the formulas for calculating the correlation coeffi cients of high-order modal responses are deduced in this study, including displacement, velocity and velocity-displacement correlation coeffi cients. Furthermore, the relationship between high-order displacement and velocity covariance is derived to make the CCQC-R algorithm only relevant to the high-order displacement response spectrum. Finally, a practical step-by-step integration procedure for calculating high-order displacement response spectrum is obtained by changing the earthquake ground motion input, which is evaluated by comparing it to the theory solution under the sine-wave input. The method derived here is suitable for generally linear systems with classical or non-classical damping.

题目

Signature of Fault Healing in an Aftershock Sequence? The 2008 Wenchuan Earthquake

作者

S HENGFENG Z HANG , 1 Z HONGLIANG W U , 1 and C HANGSHENG J IANG 1

发表刊物

《Pure and Applied Geophysics》

摘要

We analyzed the aftershock sequence of the 2008 Wenchuan earthquake from May 12, 2008 to May 12, 2013 using the earthquake catalog of the China Earthquake Networks Center (CENC). In the analysis performed, we took under consideration the temporary variation in the completeness of the earthquake catalog just after the Wenchuan mainshock. The cutoff completeness magnitude from May 12 to June 27, 2008 was above 3.0 due to
the impact of the earthquake sequence on the seismological observatory practice. It was observed that the b value has an increasing trend from June 27, 2008 to late April 2009, while since May 2009, the b value has remained stable. If these characteristics were associated with the possible signature of fault healing, the apparent healing time’ could be pinpointed by this measure as around 1 year. Due to two strong asperities present on the rupture
of the Wenchuan mainshock, the aftershock zone can be divided into two segments, namely the north and the south segment. The b values of the two segments seem to show different trends of temporal variation. The main contribution of the increasing trend comes from the south segment, or the ‘initiation segment’ of the main rupture.