钢-混凝土组合剪力墙抗震研究与发展

剪力墙是高层建筑抗震的主要抗侧力体系,随着大型复杂高层建筑的快速发展,对剪力墙抗震性能的要求也越来越高,钢-混凝土组合剪力墙就是一种抗震性能好的剪力墙。国内外在钢-混凝土组合剪力墙抗震研究方面,从抗震性能到设计方法和工程应用都取得了较快的发展。本文介绍了国内外有关钢-混凝土组合剪力墙抗震研究的部分成果,同时介绍了笔者提出的钢-混凝土多重组合剪力墙及其抗震研究情况,包括工程应用情况。已有研究表明:钢-混凝土组合剪力墙特别是钢-混凝土多重组合剪力墙,具有良好的抗震屈服机制和多道抗震防线,抗震耗能能力强,工程应用价值较大。     

利用MTMD和MTLD控制拱桥振动试验研究

本文以金沙江通阳大桥的振动控制为研究背景。结合有限元分析手段,利用MTMD控制拱桥竖向振动、MTLD控制拱桥侧向振动。对比例为1∶50的模型拱桥进行试验研究,测试结果表明,拱桥的竖向最大减振效果能够达到36.03%,侧向最大减振效果能够达到38.6%,总体控制效果令人满意。     

基于数据一致性预测与压制自由表面多次波--理论研究与试处理

从声波波场理论出发,首先在不考虑自由表面反射的情况下研究了有效波波场传播及反射规律,继而考虑自由表面反射的情况,并详尽推导了压制自由表面多次波的正演和反演数学模型。从物理本质上对自由表面多次波的产生、预测及压制做了深入的剖析,讨论了基于数据一致性时空域褶积的多次波预测方法原理,实现了自由表面相关多次波自适应压制的迭代方法过程。复杂起伏海底的理论模型试算实例表明：在多次波产生系统非常复杂的情况下,本方法仍能非常有效地压制各种与自由表面相关的多次波,同时还能很好地保持有效波的能量,取得了很好的压制多次波效果。     

RESPONSE SPECTRA FOR DIFFERENTIAL MOTION OF COLUMNS

The validity of the response spectrum concept for determining loads in structures excited by differential earthquake ground motion is examined. It is shown that the common definition of response spectrum for synchronous ground motion can be reconciled to remain valid in cases when the columns of extended structures experience different motions. Then, a relative displacement response spectrum for design of first-storey columns, SDC(T, δ, ζ, τ), is defined. In addition to natural period, T, and fraction of critical damping, ζ, this spectrum depends also on the ‘travel time’, τ (of the waves in the soil over distances about one half width, or length of the structure), and on a factor, δ, specifying the relative displacement of the first floor. It is shown how this spectrum can be determined using existing empirical scaling equations for relative displacement spectra SD(T, ζ) and for peak velocity and peak acceleration of strong ground motion. These new spectra are illustrated for a horizontal component of a record in the near field of the 1994 Northridge earthquake. The results show that differential motions are more important for short period (stiff) than for longer period (flexible) structures, and for structures founded on softer ground (small shear wave velocity). © 1997 by John Wiley & Sons, Ltd.     

平面波域反数据处理压制多次波方法研究

在地震勘探领域,尤其是海洋地震勘探中,多次波一直是影响地震处理与解释的主要因素之一.本文基于x-t域的反馈模型及多次波衰减的理论,详尽推导了x-t域反数据处理的方法;基于平面波域多次波的产生机制,借鉴x-t域反数据处理的方法,推导出在平面波域进行反数据处理的原理.文中给出一个有限差分的模拟数据进行测试,处理结果表明,本方法可以有效地衰减表层相关多次波,提高地震数据分析的精确性,在保护了一次波能量的同时,可以更加有效快捷地去除多次波.     

基于DEM的大别-皖南山区平均洪峰滞时定量分析

以皖南山区及大别山区27个中小流域为研究对象,基于数字高程模型DEM提取流域地貌信息,并计算流域平均洪峰滞时.通过建立多元线性回归及通径分析数学模型,探讨地貌因子对流域洪水响应过程的影响.结果表明:在流域系统水平,形状系数、圆度比、流域相对高差、河道分支频率以及森林覆盖率是影响流域平均洪峰滞时的主要指标,其中流域相对高差是相关系数最高的解释变量;各地貌因子间相互作用复杂,其多元线性回归模型对平均洪峰滞时的方差解释量为73.4%,其通径分析模型分别从直接作用及间接作用角度进一步合理阐述各变量对流域平均洪峰滞时的影响.本文可为皖南山区无资料地区分析洪水响应过程提供重要参考,对防洪减灾有显著意义.     

2007年5月—2013年12月成都、西昌和重庆台地磁转换函数的时间变化

本文较详细地讨论了地磁转换函数的计算方法,介绍了复转换函数实部和虚部的误差公式．利用成都、 西昌和重庆3个地磁台2007年5月—2013年12月的地磁数字化资料,计算出转换函数A,B及帕金森矢量．结果表明,在2008年汶川MS8.0地震前后成都台存在可察觉的小鼓包,而西昌、 重庆两台则没有可察觉的异常．另外与20世纪80年代的结果比较,汶川地震前后成都台的b值和帕金森矢量的长度及方向都有明显的长期变化.     

海洋坡折带地震资料处理关键技术

琼东南盆地坡折带紧邻富烃凹陷,具有良好的油气勘探前景,陆架到陆坡之间水深从200 m迅速加深至2000m.坡折带这种特殊海底地貌形成了复杂的地震波场,资料多次波发育且信噪比低.本文从正演模拟和原始野外记录资料分析了坡折带地震资料特征及处理的难点,提出了多次波衰减及深度域速度建模技术对策,实现了良好偏移成像.     

Multiple attenuation using λ-f domain high-resolution Radon transform

The parabolic Radon transform has been widely used in multiple attenuation. To further improve the accuracy and efficiency of the Radon transform, we developed the 2- fdomain high-resolution Radon transform based on the fast and modified parabolic Radon transform presented by Abbad. The introduction of a new variable 2 makes the transform operator frequency-independent. Thus, we need to calculate the transform operator and its inverse operator only once, which greatly improves the computational efficiency. Besides, because the primaries and multiples are distributed on straight lines with different slopes in the 2-fdomain, we can easily choose the filtering operator to suppress the multiples. At the same time, the proposed method offers the advantage of high-resolution Radon transform, which can greatly improve the precision of attenuating the multiples. Numerical experiments suggest that the multiples are well suppressed and the amplitude versus offset characteristics of the primaries are well maintained. Real data processing results further verify the effectiveness and feasibility of the method.     

Hydroclimate variability and long-lead forecasting of rainfall over Thailand by large-scale atmospheric variables

Abstract

The development of statistical relationships between local hydroclimates and large-scale atmospheric variables enhances the understanding of hydroclimate variability. The rainfall in the study basin (the Upper Chao Phraya River Basin, Thailand) is influenced by the Indian Ocean and tropical Pacific Ocean atmospheric circulation. Using correlation analysis and cross-validated multiple regression, the large-scale atmospheric variables, such as temperature, pressure and wind, over given regions are identified. The forecasting models using atmospheric predictors show the capability of long-lead forecasting. The modified k-nearest neighbour (k-nn) model, which is developed using the identified predictors to forecast rainfall, and evaluated by likelihood function, shows a long-lead forecast of monsoon rainfall at 7–9 months. The decreasing performance in forecasting dry-season rainfall is found for both short and long lead times. The developed model also presents better performance in forecasting pre-monsoon season rainfall in dry years compared to wet years, and vice versa for monsoon season rainfall.

Editor Z.W. Kundzewicz

Citation Singhrattna, N., Babel, M.S. and Perret, S.R., 2012. Hydroclimate variability and long-lead forecasting of rainfall over Thailand by large-scale atmospheric variables. Hydrological Sciences Journal, 57 (1), 26–41.