南宁市强对流暴雨降水特征及成因初探

对1955～2000年发生在南宁市的强对流暴雨的降水特征作了较系统的分析,得出5～8月是强对流暴雨多发期,以单个雨团影响最为普遍,易发生在水汽和不稳定层结垂直分布极不均匀的环境场中。     

A simplified method of constructing fragility curves for highway bridges

Fragility curves are found to be useful tools for predicting the extent of probable damage. They show the probability of highway structure damage as a function of strong motion parameters, and they allow the estimation of a level of damage probability for a known ground motion index. In this study, an analytical approach was adopted to develop the fragility curves for highway bridges based on numerical simulation. Four typical RC bridge piers and two RC bridge structures were considered, of which one was a non‐isolated system and the other was an isolated system, and they were designed according to the seismic design code in Japan. From a total of 250 strong motion records, selected from Japan, the United States, and Taiwan, non‐linear time history analyses were performed, and the damage indices for the bridge structures were obtained. Using the damage indices and ground motion parameters, fragility curves for the four bridge piers and the two bridge structures were constructed assuming a lognormal distribution. It was found that there was a significant effect on the fragility curves due to the variation of structural parameters. The relationship between the fragility curve parameters and the over‐strength ratio of the structures was also obtained by performing a linear regression analysis. It was observed that the fragility curve parameters showed a strong correlation with the over‐strength ratio of the structures. Based on the observed correlation between the fragility curve parameters and the over‐strength ratio of the structures, a simplified method was developed to construct the fragility curves for highway bridges using 30 non‐isolated bridge models. The simplified method may be a very useful tool to construct the fragility curves for non‐isolated highway bridges in Japan, which fall within the same group and have similar characteristics. Copyright © 2003 John Wiley & Sons, Ltd.     

近场强地震动模拟中对破裂的方向性效应和上盘效应的表达.

为了模拟近场强地震动，采用了基于有限断层模型的一种随机合成方法．震源破裂面被剖分成一定数量的子源，总的地震矩分成数量更多的子震的矩．一给定子源中一次子震引起的场地地震动的傅氏谱，通过考虑点源的谱、随着距离的衰减、能量耗散及近地表效应等导出．据此幅值谱和一个随机相位谱，并与一个时程包络函数结合，合成一个子震时程．将各子源中各个子震引起的所有时程叠加，得出场地的地震动时程．叠加中，各子震时程之间的时滞，据子震发震时差和子源至场地的距离差别引起的时差确定．对一个设定地震，选用4个断层面倾角，计算了近场21个地点的地震动．结果表明，本文方法可以很好地表达破裂的方向性效应和上盘效应．为了验证方法的可靠性，对1994年美国北岭地震中3个近断层台站MCN，LV3和PCD模拟的地震动与实际记录的加速度反应谱和时程作了比较．      

青藏高原北部地区7级强震的有序网络特征及其预测研究

青藏高原北部地区7级强震具有显著的有序性，根据翁文波信息预测理论分析讨论了本区7级强震信息有序网络结构特征，并据此对未来强震进行预测：下次7级强震可能发生在2006—2007年，研究结果表明，有序网络结构可能是大地震形成的一种机制。     

Study on the severest real ground motion for seismic design and analysis

How to select the adequate real strong earthquake ground motion for seismic analysis and design of trucures is an essential problem in earthquake engineering research and practice.In the paper the concept of the severest design ground motion is proposed and a method is developed for comparing the severity of the recorded strong ground motions.By using this method the severest earthquake ground motions are selected out as seismic inputs to the structures to be designed from a database that consists of more than five thousand significant strong ground moton records collected over the world.The selected severest ground motions are very likely to be able to drive the structures to their critical response and thereby result in the highest damage potential.It is noted that for different structures with diffferent predominant natural periods and at different sites where structures are located the severest design ground motions are usually different.Finally.two examples are illustrated to demonstrate the rationality of the concept and the reliability of the selected design motion.     

瑞雷面波在填海造地强夯检测工程中的应用

瑞雷面波在填海造地强夯效果检测中 ,较常规静力学方法具有成本低、效率高、适宜大面积检测的人工地震勘测方法。本文以漳州后石电厂填海造地的强夯效果检测为例 ,给出瑞雷面波检测方法在强夯效果检测应用的技术途径、技术方案 ,并对检测效果进行分析     

沙尘暴问题的经济学分析

沙尘暴也是一个经济问题，引发沙尘暴的主要原因是人类不合理的经济活动，而其根本原因在于制度安排的不合理和低效率，该文从人口，博弈论，产品价格三方面进行了分析。     

Cyclic‐demand spectrum

The seismic response spectrum defines the amplitude of the load, but it does not specify the number of cycles for which the load must be resisted by the structure. The amplitude by itself is not sufficient to evaluate the seismic resistance of a structure, because the structure's strength, stiffness and energy‐dissipation capacity reduce with an increase in the number of load cycles. This paper presents a cyclic‐demand spectrum, which, in conjunction with the amplitude spectrum, provides a more complete definition of the seismic load, hence a way to consider the degradation in strength, stiffness and energy‐dissipation capacity in a rational manner. Similarly to three amplitude parameters (peak ground acceleration, peak ground velocity, and peak ground displacement), three cyclic‐demand parameters are introduced for stiff, moderately stiff, and flexible systems. A design example is presented to illustrate the use of the cyclic‐demand spectrum. Copyright © 2002 John Wiley & Sons, Ltd.     

Experimental analysis of seismic torsional ground motion recorded by the LSST‐Lotung array

The purpose of this study was to perform an experimental analysis of the amplitude of full‐scale spatial variability of seismic motions with regard to earthquake engineering. The LSST‐Lotung array in Taiwan provides a good set of records for this type of study. Of interest are the free‐field torsional seismic components induced by the spatial variability of seismic motions. In this study, three events have been considered: LSST‐06, LSST‐07 and LSST‐16. In time domain analysis, the experimental results obtained show that when the separation distance increases, the induced torsion decreases, and the normalized differential motion parameter increases. Also, the results show that the stronger the event, in terms of maximum PGA, the larger the induced torsional amplitude and the smaller the induced normalized differential motion parameter. Copyright © 2002 John Wiley & Sons, Ltd.