渭河盆地中土层场地对地震动的放大作用   总被引：11，自引：1，他引：10       下载免费PDF全文

王海云 《地球物理学报》2011,54(1):137-150

土层场地对地震动的影响较大,建(构)筑物的选址及其抗震设防必须考虑土层场地的放大作用,以避免或减轻其震害.汶川地震中,布设在渭河盆地中的数字强震动台网共有27个台站(包括2个基岩台站和25个土层台站)获得良好的主震加速度时程.利用这些加速度时程,选择汤峪台做为参考场地,基于考虑几何衰减的传统谱比法分析研究了25个土层场...  相似文献   

Modeling of the Second Indirect Effect of Anthropogenic Aerosols in East Asia          下载免费PDF全文

WU Peng-Ping  HAN Zhi-Wei 《大气和海洋科学快报》2011,4(6):316-323

This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the second indirect effect was also characterized.The simulation period for this study was 2006.Due to a decrease in autoconversion rate from cloud water to rain as a result of aerosols,the cloud liquid water path(LWP) ,and radiative flux(RF) at the top of the atmosphere(TOA) changed dramatically,increasing by 14.3 g m-2 and decreasing by-4.1 W m-2 in terms of domain and annual average.Both LWP and RF changed most in autumn. There were strong decreases in ground temperature in Southwest China,the middle reaches of the Yangtze River in spring and autumn,while maximum cooling of up to-1.5 K occurred in the Chongqing district.The regional and annual mean change in ground temperature reached-0.2 K over eastern China.In all seasons except summer,precipitation generally decreased in most areas north of the Yangtze River,whereas precipitation changed little in South China.Precipitation changed most in summer,with alternating bands of increasing(～40 mm) and decreasing(～40 mm) precipitation appearing in eastern China.Precipitation decreased by 1.5-40 mm over large areas of Northeast China and the Huabei Plain.The domain and annual mean change in precipitation was approximately-0.3 mm over eastern China.The maximum reduction in precipitation occurred in summer,with mean absolute and relative changes of-1.2 mm and-3.8%over eastern China.This study revealed considerable climate responses to the second indirect effect of aerosols over specific regions of China.  相似文献   

The extended N2 method taking into account higher mode effects in elevation   总被引：1，自引：0，他引：1  

Maja Kreslin  Peter Fajfar 《地震工程与结构动力学》2011,40(14):1571-1589

The N2 method has been extended in order to take into account higher mode effects in elevation. The extension is based on the assumption that the structure remains in the elastic range when vibrating in higher modes. The seismic demand in terms of displacements and storey drifts can be obtained by enveloping the results of basic pushover analysis and the results of standard elastic modal analysis. The approach is consistent with the extended N2 method used for plan‐asymmetric buildings. The proposed procedure was applied to three variants of three steel frame buildings used in the SAC project. The structural response was investigated for two sets of ground motions. Different ground motion intensities were used in order to investigate the influence of the magnitude of plastic deformations. The N2 results were compared with the results of nonlinear response‐history analysis, two other pushover‐based methods (modal pushover analysis (MPA) and modified MPA (MMPA)), and pushover analysis without consideration of higher modes. It was found that a considerable influence of higher modes on storey drifts is present at the upper part of medium‐and high‐rise structures. This effect is the largest in the case of elastic behaviour and decreases with ground motion intensity. The higher mode effects also depend on the spectral shape. The approximate methods (extended N2, MPA and MMPA) are able to provide fair estimates of response in the case of the test examples. Accuracy decreases with the height of the building, and with the intensity of ground motion. The N2 results are generally conservative. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

汶川Ms8.0地震灾害的非对称分布与成因分析          下载免费PDF全文

周庆  张春山  陈献程 《地震学报》2011,33(4):492-504

在汶川Ms8.0地震中,地震灾害在灾区相对于发震断层,呈现各种非对称分布.断层高角度逆冲诱发的崩塌、滑坡的规模与数量在断层上盘区远远高于断层下盘区,在垂直断层方向,高烈度区断层上盘宽度往往大于下盘宽度,上述不对称性反映了逆断层型地震存在加速度峰值的上盘效应;而在破裂的传播方向存在的地震波多普勒效应则造成沿长轴方向东北部...  相似文献   

Broadband Analytical Solution to the Scattering of Plane SV Waves by Circular Cylindrical Canyons     

Zhong Hui  Zhang Yushan 《中国地震研究》2011,25(1):13-27

Based on Fourier-Bessel series expansion of wave functions,an analytical solution to 2-D scattering ofincident plane SV waves by circular cylindrical canyons with variable depthto-width ratios is deduced in this paper. Unlike other analytical solutions,this paper uses the asymptotic behavior of the cylindrical function to directly define the undetermined coefficients of scattered waves,thus,avoiding solving linear equation systems and the related numerical computation problems under high-frequency incident waves,thereby broadening the applicable frequency range of analytical solutions. Through comparison with existing analytical solutions,the correctness of this solution is demonstrated. Finally, the incident plane SV wave scattering effect under circular cylindrical canyons in wider frequency bands is explored.  相似文献   

平面不对称结构非弹性地震反应分析的平扭耦联Bouc-Wen模型     

余波  杨绿峰 《地震工程与工程振动》2011,31(6):78-87

综合考虑强度退化、刚度退化、捏拢效应等典型滞回特性的影响,建立了双向地震作用下平面不对称结构非弹性地震动力响应分析的平扭耦联Bouc-Wen模型.该模型采用圆形屈服面来描述双向抗侧恢复力之间的耦合效应,而采用锥体或球体屈服面来描述双向抗侧和抗扭恢复力之间的耦合效应,并结合69条强震记录,定量地分析了平扭耦联效应对平面不...  相似文献   

结构-地基体系水平与扭转位移耦合效应研究     

姜南  赵慧芳 《地震工程与工程振动》2011,31(5):142-148

采用动力理论对地基-结构非线性相互作用体系的振动方程进行了定性分析.基于多线性随动强化模型,采用非线性有限元法求解了基础和地基土之间的水平刚度与摇摆刚度,建立了结构-地基非线性相互作用体系的力学模型.利用拉格朗日能量法推导了结构水平位移和扭转相耦合的振动方程.采用多尺度法研究了结构-地基相互作用体系的主共振.通过分析不...  相似文献   

福建城乡震灾快速评估系统设计     

王辉山  傅再扬  于威宇  陈琳 《地震地磁观测与研究》2011,32(6):150-155

充分借鉴目前国内外工程地震和震害预测研究成果,结合福建实际震例,利用GIS技术、Web技术,设计开发区域范围震害预测及震灾快速评估系统,即福建城乡震灾快速评估系统.利用该系统平台对1992年以来发生在福建有较大影响的6次中强地震进行震灾快速评估,并将系统评估计算结果与实际震害调查评估结果进行对比分析,给出系统评估结果与...  相似文献   

高山峡谷场地地震动水平峰值加速度传播特性研究     

张玉敏  李幻  朱泽奇 《世界地震工程》2011,27(3)

建立了高山峡谷场地的动力计算模型,分析了攀枝花地震动作用下场地水平峰值加速度(HPA)的衰减效应,研究了不同参数对场地HPA传播特性的影响。数值分析结果表明:HPA随深度增加而衰减,HPA在坡脚处比在峡谷处要低一些;在山顶处有放大效应,但放大系数比实际震害要小一些;HPA衰减程度随着阻尼比和模型深度的增加而增加,随着坡比增加而减小,且不受输入地震动峰值加速度影响;在不同频谱特性地震动作用下,当地震波的卓越频率接近计算模型的自振频率时,场地衰减程度会随之增大。  相似文献   

Simulation of spatially correlated earthquake ground motions for engineering purposes   总被引：4，自引：4，他引：0  

Yongxin Wu  Yufeng Gao  Dayong Li 《地震工程与工程振动(英文版)》2011,10(2):163-173

A new model to simulate spatially correlated earthquake ground motions is developed. In the model, the main factors that characterize three distinct effects of spatial variability, namely, the incoherency effect, the wave-passage effect and the site-response effect, are taken into account, and corresponding terms/parameters are incorporated into the well known model of uniform ground motions. Some of these terms/parameters can be determined by the root operation, and others can be calculated directly. The proposed model is fi rst verif ied theoretically, and examples of ground motion simulations are provided as a further illustration. It is proven that the ensemble expected value and the ensemble auto-/cross-spectral density functions of the simulated ground motions are identical to the target spectral density functions. The proposed model can also be used to simulate other correlated stochastic processes, such as wave and wind loads.  相似文献