向心式变摩擦阻尼器控制结构地震反应分析

介绍了向心式变摩擦阻尼器的原理及其基本力学性能,探讨了安装向心式变摩擦阻尼器结构在自由振动和强迫振动时的动力特性和动力反应特点,揭示了向心式变摩擦阻尼器引起结构抖振的机理,对安装向心式变摩擦阻尼器的结构的地震反应进行了分析,研究了向心式变摩擦阻尼器的参数对结构动力特性及地震反应的影响,给出了受控结构的非线性反应谱.     

土-结构接触面对圆形隧道动力反应的影响

土与地下结构在强震作用下可能会发生脱离和滑移,对地下结构的动力特性有较大的影响。研究了FLAC软件中接触面单元的力学原理,利用该软件对圆形隧道进行了地震反应模拟分析,对比分析了土与隧道衬砌之间考虑滑移与未考虑滑移两种情况下隧道的动力响应,给出了隧道衬砌不同位置处围岩与衬砌相对滑移量的分布规律。结果表明:考虑土与衬砌之间的滑移时,隧道衬砌的动轴力极值要明显低于未考虑滑移的情况;隧道衬砌的动弯矩极值和动剪力极值要高于未考虑滑移时的结果;圆形隧道的底部与两侧滑移量较大。在实际抗震设计中应考虑土与衬砌之间滑移对隧道抗震性能的影响。     

考虑动水压力影响的单柱式桥墩地震反应分析

在Morison方程的基础上,用附加水质量法考虑动水压力对桥墩的影响,以单柱式桥墩为研究对象,以ABAQUS有限元软件为计算平台,建立了考虑桩-土动力相互作用的单柱式桥墩地震反应分析模型,考虑土体和桥墩混凝土的动力非线性特征,分析了地震动作用下动水压力对单柱式桥墩的墩顶相对墩底位移、加速度、剪力和弯矩反应的影响,并探讨了水位对单柱式桥墩地震反应特性的影响。结果表明:动水压力改变桥墩的地震反应特性,增大了桥墩顶部相对底部的位移、墩顶绝对加速度和墩底的内力,水位变化影响桥墩的地震反应特性。对于深水桥墩抗震设计计算,考虑动水压力效应、水位变化是有必要的。     

农居抗震房与隔震房地震动输入有限元分析

使用SAP2000有限元软件对新疆农村地区典型单层砌体抗震房与采用摩擦滑移隔震技术的同户型隔震房进行地震反应对比分析。考虑在不同设防烈度情况下结构的地震反应变化规律。对结构的模态、顶部绝对加速度和层间位移反应进行了比较,验证了摩擦滑移隔震体系的隔震性能。     

强地震动作用下地铁结构与土脱开滑移的研究

应用反应位移法,有限元反应位移法和有限元动力分析方法,以兵库县南部地震的Port-Island观测波形作为地震动输入,对某给定地质条件下的浅埋箱型地铁结构进行了不考虑结构与土脱开滑移和考虑结构与土脱开滑移的两种情况的计算,通过计算可以了解到一般箱型结构与上脱开,滑移的位置和范围,计算结果表明,抗震设计时,在强地震作用下,结构与土的脱开,滑移作用考虑与否,对结构变形和断面力计算值的影响很大。     

多维多点激励下考虑支座摩擦滑移及结构碰撞的非规则桥梁抗震性能研究

以一座典型山区非规则梁桥为研究对象,建立了该桥梁多维多点激励下的多自由度动力计算模型,研究了该桥梁在多维多点激励下考虑支座摩擦滑移及结构碰撞等非线性因素时的抗震性能。研究结果表明:相比一维地震输入,多维地震可使结构的动力响应增加,桥墩底部弯矩需求增大;相比一致激励,多点激励可使得支座的位移需求增大,且地震波最后到达的桥墩上方支座位移最大;同时考虑多点激励和碰撞效应可使桥墩的弯矩需求增加;水平地震作用下,矮墩上部的支座容易滑动,且双向地震较单向地震更明显,三向地震输入较双向有所增强。因此,对山区非规则梁桥进行抗震设计时应有针对性地进行多维多点地震输入计算,找出结构的最大地震需求,以期指导设计。     

浮放设备地震滑移反应数值模拟研究

以前人研究建立的浮放设备滑移反应分析理论为基础,给出了浮放设备在水平和竖向地震输入下滑移反应运动微分方程,选取连续型的库仑摩擦力模型,采用Runge-Kutta法求解浮放设备地震滑移反应运动微分方程,可以得到浮放设备在地震作用下的绝对加速度、相对速度和相对位移反应时程。采用编制的计算程序,进行了浮放设备地震滑移反应参数影响研究,结果表明:浮放设备水平滑移反应随着水平地震地面输入或楼层反应输入的增大而增大,随着设备与支撑面之间摩擦系数的增大而减小;当水平向输入加速度峰值大于0.3g时,需要考虑竖向激励的影响。     

部分柱顶滑移钢筋混凝土框剪结构的简化分析

本文推导了弹性状态下部分柱顶滑移钢筋混凝土框剪结构在摩擦支座滑移和不滑移两种情况下的基本微分方程及周期、位移、内力计算公式,并给出了算例比较。研究表明:(1)摩擦支座滑移情况相比不滑移情况,周期增大,总水平地震作用减小,顶点位移及最大层间位移角均有所减小,总剪力墙的最大弯矩和最大剪力、总框架的层剪力有较大幅度减小;(2)摩擦支座滑移带来的附加剪切刚度比摩擦支座滑移前总滑移柱剪切刚度小;(3)中震或大震当主体结构基本处于弹性工作阶段时,考虑摩擦支座滑移进行计算分析比不考虑摩擦支座滑移更加经济。     

堆芯燃料组件抗震计算关键参数的敏感性分析

堆芯燃料组件作为核电厂反应堆中的抗震Ⅰ类部件，其在地震作用下是否会发生显著变形或破坏，将关系到整个燃料组件的完整性和反应堆的安全性。针对堆芯燃料组件的结构特性，结合堆芯燃料组件抗震性能评价准则中的具体评价要求，研究构建堆芯燃料组件抗震分析计算模型的简化方法。在此基础上，结合组件简化模型中的四类抗震计算关键参数，进一步分析各关键参数对单组件简化模型动力学特性和多组件堆芯模型抗震分析计算的影响，从而更加准确的把握各关键参数对组件抗震计算的影响程度，为相关设计和核安全审评提供参考。     

有横缝拱坝的非线性动力模型试验和计算分析研究

本文通过在大型三向地震模拟振动台上进行的设置伸缩横缝的某拱坝非线性动力模型试验，应用非线性有限元动力分析程序同时进行计算分析，全面系统地研究了拱坝横缝对坝体动力特性和地震反应的影响，并对计算程序进行了改进。试验与计算结果相互印证，验证了试验成果的可靠性和计算分析模型、计算程序与计算结果的合理性。     

Nonlinear seismic response analysis of arch dam-foundation systems- part I dam-foundation rock interaction

The arch dam–foundation rock dynamic interaction and the nonlinear opening and closing effects of contact joints on arch dam are important to the seismic response analysis of arch dams. Up to date, there is not yet a reasonable and rigorous procedure including the two factors in seismic response analysis. The methods for the analysis of arch dam–foundation rock dynamic interaction in frequency domain are not suitable to the problem with nonlinear behaviors, in this paper, so an analysis method in time domain is proposed by combining the explicit finite element method and the transmitting boundary, and the dynamic relaxation technique is adopted to obtain the initial static response for dynamic analysis. Moreover, the influence of arch dam–foundation dynamic interaction with energy dispersion on seismic response of designed Xiaowan arch dam in China is studied by comparing the results of the proposed method and the conventional method with the massless foundation, and the local material nonlinear and nonhomogeneous behaviors of foundation rock are also considered. The reservoir water effect is assumed as Westergaard added mass model in calculation. The influence of the closing–opening effects of contact joints of arch dam on the seismic response will be studied in another paper.     

高速铁路桥梁-桥墩-桩基础-地基耦合系统的地震反应

高速铁路中的桥梁常采用灌注桩基础以控制沉降,地震作用是桩基础的设计工况之一。建立桥梁-桥墩-桩基础-地基为一体的耦合系统非线性三维数值分析模型,以典型地震波为输入,考虑上部结构和基础的共同工作、土-结构动力相互作用、材料非线性和土层对桩的侧阻及端阻作用,开展三向地震作用下的动力有限元计算,并对地基主要土层压缩模量、桩体材料弹性模量、桩径和桩长进行参数敏感性分析。计算结果表明:现行的桩基础设计方案能有效控制地震荷载作用下桥梁的变形;地震过程中的不同时刻,桩侧阻发挥程度不同且不可忽略,以单纯的梁单元模拟桩的动力学行为的适用性值得商榷;桩长和地基主要土层压缩模量对桥梁地震反应影响最大,桩体材料弹性模量的影响次之,桩径的影响最小。     

Clayey injection veins and pseudotachylyte from two boreholes penetrating the Chelungpu Fault, Taiwan: Their implications for the contrastive seismic slip behaviors during the 1999 Chi-Chi earthquake

Abstract   The seismic slip that occurred during the 1999 Chi-Chi earthquake in Taiwan showed contrastive behaviors in different regions along the Chelungpu Fault: A large and smooth slip occurred in the north, while a relatively small slip associated with high-frequency seismic wave radiation occurred in the south. The core samples from shallow boreholes at northern (Fengyuan) and southern (Nantou) sites penetrating the seismic Chelungpu Fault were analyzed. The fault zones at the northern site are characterized by soft clayey material associated with clayey injection veins. This suggests that the fault zones were pressurized during ancient seismic slip events, and hence the elastohydrodynamic lubrication occurred effectively. In contrast, the fault rock from the southern site is old pseudotachylyte that has been shattered by repeated ancient seismic slip events. Statistical analysis of many pseudotachylyte fragments reveals that the degree of frictional melting tended to be low. In this case, the seismic slip is restrained by the mechanical barrier of a highly viscous melt layer. These contrastive fault rocks were produced by repeated ancient seismic slip events, but the two corresponding mechanisms of friction are likely to have also occurred during the 1999 Chi-Chi earthquake, thus causing the contrastive slip behaviors in the north and south.     

震源动力学破裂过程数值模拟研究

首先阐述了震源动力学过程研究的重要意义, 在此基础上, 研究了复杂的断层几何形态及介质模型对动力学破裂过程的影响, 并对常用的有限元方法、 离散元方法、 有限差分方法和边界积分方程方法等进行了相应介绍. 讨论了这些数值模拟方法各自的优缺点, 建议在方法的选择上应视具体问题及计算的精度而定. 最后对动力学数值模拟的关键部分, 滑动摩擦准则进行了论述. 常用的滑动摩擦准则有滑动弱化准则、 速率弱化准则和速率-状态依赖摩擦准则. 在单纯考虑某个地震的动力学破裂传播过程时, 滑动弱化准则较为常用, 其中滑动弱化距离的选取至关重要. 但若考虑整个地震循环, 速率-状态依赖摩擦准则更为合适.      

大型河谷场地地震动特性研究

采用有限差分方法,通过算例研究了大型河谷场地地震动特性分析中的人工边界的选取方法,对比分析了不同人工边界的选取对数值模拟结果的影响,确定了散射场地震反应分析输入边界的地震动输入方法,认为在进行有限差分动力计算时,模型两侧施加自由场边界的模拟效果要优于两侧施加粘性边界的模拟效果;同时,对FLAC计算软件进行二次开发,对2个地形差异较大的河谷场地,采用线性和非线性摩尔-库仑模型进行了地震反应对比分析,研究了河谷场地地震动幅值和频谱特性随地形变化的规律。模拟数据表明,河谷场地谷底处地震动基本无放大作用,地势凸起处放大作用则较为明显;当考虑土体非线性时,随着地震动强度的增加,放大作用逐渐减小;谱分析结果表明,地势凸起处受高频地震动的影响显著,而地势平坦的谷底则受低频地震动的影响显著。     

海原大地震诱发石碑塬黄土滑坡机制探讨

1920年海原8.5级大地震诱发的石碑黄土塬滑坡,因其规模大、坡度小、滑距远的特点成为业界关注焦点,目前对该滑坡的物理力学过程仍无统一认识。基于此,文章通过理论分析和数值计算方法研究该滑坡初始状态、地震动力响应和流滑发展过程。为分析震前斜坡初始状态,建立考虑斜坡表面拉裂缝中侧向水压力作用的力学计算模型。结果表明,拉裂缝中侧向水压力削弱了斜坡整体稳定状态;为研究地震时斜坡动力响应过程,建立数值计算模型,获得地震时斜坡饱和土层的孔隙水压力比和斜坡位移的变化特性;为解释远程滑坡,将液化后土层等效为流体,借鉴泥流滑距估算理论,求算石碑塬滑坡的滑距,计算结果与前人现场考察结果吻合。     

A 3-D Quasi-static Model for a Variety of Slip Behaviors on a Subduction Fault

— Earthquake faultings have a wide variety of slip behaviors, such as, a log-linear frequency-magnitude relation, characteristic earthquakes, slow slip events, and so on. We report a model which can reproduce a certain variety of observed complex slip behaviors on a fault. Our 3-D model simulates the seismic cycle on a shallow dipping subduction fault in a homogeneous elastic half-space, on which frictional sliding is controlled by a rate- and state-dependent friction law. We find that the behaviors of reproduced seismic cycles depend on a lateral dimension of a seismogenic zone (H) with respect to a constant seismogenic width in dip direction (W). The following three domains appear in the seismic cycle behaviors: (1) Regular, periodic behaviors when H is comparable to W; (2) transitional, quasi-periodic behaviors when H/W~ 3; and (3) complex behaviors when H/W is larger than about 4. The slip behavior in the domain (1) is characterized by a periodical recurrence of a characteristic earthquake, which is centered in strike direction. In the domain (2), although earthquakes are still centered, these recurrence intervals and the sizes are modulated within a certain range. Also, in the domain (3), earthquakes occur not only at the center but at various lateral positions on the seismogenic zone. In this domain, the log-linear frequency-magnitude relations, like the Gutenberg-Richter relation, are produced. Slow slip events also occur at source areas of the earthquakes. It is suggested that a heterogeneous stress distribution at a source region is important, as well as heterogeneities in friction properties on the fault, for understanding the wide variety of slip behaviors in faultings.     

Linearization of rigid body dynamics on frictional interfaces under harmonic loading

The non-linear dynamic response of the rigid block is linearized by means of a friction model that implicitly considers block response through an experimental parameter obtained from shaking table experiments. In view of the great difficulty in carrying out shaking table experiments, in this technical note some recommendations to estimate friction model parameters are given. The selection of parameters considers the sliding response mode of the block–plane-excitation system: stick–slip or continuous sliding. Once all the friction parameters and block response mode were estimated, a methodology was proposed to compute rigid block dynamic response. The numerical results were then compared to actual experimental data for a rigid block sliding on a geotextile–wood interface, along an inclined plane subjected to base harmonic acceleration. Experiments were carried out for both the stick–slip and the continuous sliding modes. Computed and measured responses for both cases showed good agreement, thus indicating that the methodology developed in this research is adequate to capture the physics (of non-linear nature) of rigid blocks sliding on frictional interfaces subjected to complex harmonic loading. The findings encourage the extension of the linearization technique to the more general seismic loading case.     

近断层脉冲型地震动作用下高层摩擦摆基础隔震结构的减震性能研究

近断层地震动中长周期、短持时和高能量的加速度脉冲将对高层摩擦摆基础隔震结构的减震性能产生不利影响,考虑土-结构相互作用（SSI效应）后的隔震结构将产生动力耦合效应,可能进一步放大隔震结构地震响应。为此,通过一幢框架-核心筒高层摩擦摆基础隔震结构的非线性地震响应分析,考察近断层脉冲型地震动作用下框架-核心筒摩擦摆基础隔震结构的层间位移角、楼层加速度和隔震层变形等响应规律,揭示隔震体系的损伤机理。基于集总参数SR （sway-rocking）模型,分析不同场地类别与不同地震动类型对隔震体系动力响应影响规律。结果表明:高层摩擦摆基础隔震结构在近断层脉冲型地震动作用下的减震效果相比普通地震动减震效果变差,楼层剪力、层间位移角和隔震层变形等超越普通地震动作用下的1.5倍;对于Ⅲ和Ⅳ类场地类别,考虑SSI效应使隔震结构的地震响应进一步放大,弹塑性层间位移角随着土质变软增大尤为明显。