某基础隔震结构的设计与应用研究

对厦门某一幼儿园教学楼进行基础隔震设计,采用动力时程分析方法,分析结构在设防烈度下中震及大震作用下的结构响应。对比抗震结构和隔震结构两者的周期、层间剪力和层间位移,对比结果表明,相较于抗震结构,隔震结构的周期变长,隔震结构受到的地震作用效应大幅降低,上部结构的水平向减震系数为0.39。经设计验算,结构隔震设计满足我国现行建筑抗震设计规范的规定,可为类似基础隔震工程的应用提供借鉴。     

Local stiffness characteristic of geogrid-stabilized aggregate in relation to accumulated permanent deformation behavior

Accumulated permanent deformation is the primary source of damage in a pavement unbound aggregate base layer. Mechanical stabilization with the help of a geogrid installed in unbound aggregate base provides lateral restraint to the flexible pavement, however, the local stiffness characteristic of geogrid-stabilized aggregate in relation to permanent deformation behavior is not clearly known. This study presents variations in shear modulus properties of geogrid-stabilized and unstabilized aggregate specimens in relation to permanent deformation accumulation. To characterize the local stiffnesses near and far away from geogrid, two pairs of bender elements were inserted in triaxial specimens as shear wave transducers. With the number of load cycles, the variations in the shear wave velocities at two different specimen heights were monitored. The test results show that, after the specimen preparation, the shear modulus near the geogrid was greater than that far away from the geogrid. Further, the shear modulus estimated at both levels of unstabilized specimen was similar to that estimated far away from geogrid in the mechanically stabilized specimen. This study demonstrates that the local stiffness of aggregate can be monitored by using the bender elements in relation to trends in permanent deformation behavior, and suggests the bender element systems can be effectively used to validate the benefits of geogrid stabilization by quantifying local stiffnesses at various levels of accumulated permanent deformation.     

Evaluation of maximum seismic displacements of SDOF systems from their residual deformation

The post-earthquake performance level of structures provides a very important source of information both for probable rehabilitation procedures and determination of structural response to probable incoming aftershocks. This performance is described by the maximum deformation which is directly related to structural damage. On the basis of extensive parametric studies on single degree of freedom structures, empirical equations are constructed for a simple and effective determination of the maximum seismic deformation from residual displacements, which can be measured in-situ after strong seismic events. The proposed method is applied both to far-field and near-field ground motions. It is found that the measure of residual deformation can be effectively used to evaluate the post-earthquake performance level of structures.     

人工土山的地震永久变形分析

人工土山的地震稳定性评价是其设计与建造过程中的关键问题之一,目前还没有得到很好地解决。采用等效黏弹性分析理论和Newmark滑块位移法对土山的地震永久位移进行研究,分析了不同高度、坡度和地震动条件下人工土山的地震永久位移。发现当坡度较缓时,山坡最大位移滑块和拟静力法的最危险滑块不论是所处位置还是大小均有较明显差别。最后,根据土山最大地震永久位移量和屈服加速度的关系,提出利用屈服加速度估算人工土山地震永久位移的简便计算方法。     

连体高层隔震结构地震反应分析

将隔震技术应用于连体高层结构,首先利用ANSYS建立了隔震支座的双线性力学模型,进而以某实际工程为原型建立了连体高层结构的抗震及隔震结构有限元模型。通过模态信息的对比发现采用隔震支座后结构前几阶周期有显著增大,同时影响连体结构的竖向振型出现阶次也有所增加。对比El Centro波激励下的响应时程可以看出,采用隔震支座可以显著减少主塔结构层间剪力、顶层加速度及结构关键部位的杆件应力,由此证明了隔震支座在该类结构上应用可以有效提高结构的抗震安全性。     

Improving seismic performance of concrete-filled tube to base connections

This study is focused on experimentally investigating the relationship between design details and column base performance, such as strength and rigidity. Results from specimens tested under combined axial and lateral loads were used to define the effectiveness of the base connections. It was observed from test comparisons that the rigidities of the base connections increased when the embedded depths were increased. It was also found that the base connections possessed higher stiffness and energy dissipating capability when stiffeners were added to the base connections. Finally, an empirical expression for base rigidity estimation is proposed for design references.     

Seismic analysis of an asymmetric fixed base and base-isolated high-rack steel structure

Since, in the case of plan-eccentric, externally-braced, high-rack storage structures made of steel, damage to the central part of the structure can cause damage to the stored goods, and thus higher earthquake-induced costs, an investigation has been performed into the seismic performance of such structures. An actual structure was analysed both as a fixed base variant, and as a base-isolated variant. The extended N2 method (pushover analysis) was used, and the results obtained were compared with selected results obtained by nonlinear-dynamic analysis. The response of several different mass-asymmetric structural variants, corresponding to different occupancy levels of the structure, was analysed, and the results obtained are presented as floor plan projection envelopes of the top, relative and base displacements, as well as the storey drifts. An interesting result obtained in the research was that asymmetry can increase the damage in the supporting structure on the flexible side, and that the central part of the rack structure remains in the elastic region only when the eccentricity is small. In fact, from the seismic point of view, full occupancy is not the most critical condition, but rather lower occupancy, which could cause eccentricities ranging up to 10% or 15% of the larger floor plan dimension; this could lead to damage propagation in some of the columns. The application of base isolation has a positive effect on the management of seismic performance, even in the case of higher levels of occupancy and larger mass eccentricities. It is pointed out that an eccentricity of 5%, which is prescribed in Eurocode 8, might not be sufficient in such structural types, and that similar concerns could be present in other types of industrial structures with a similar ratio between live and dead loads.     

两自由度滑移隔震体系的上部结构最大地震反应分析

基础滑移隔震是提高高烈度区村镇低层建筑抗震能力的有效方法。通过输入大量地震波,对两自由度滑移隔震体系上部结构归一化峰值伪加速度进行了数值分析,研究地震动和结构特性对滑移隔震结构最大地震反应的影响,并建立了上部结构峰值伪加速度的简化计算公式。研究结果表明：归一化峰值伪加速度随着上部结构周期的增大呈先增大后减小的变化趋势,可近似保守地取归一化峰值伪加速度平均值的最大值作为滑移隔震结构的最大地震反应;滑移发生后,震级、震中距及近场脉冲对结构响应的影响较小,动静摩擦系数差异的影响也可忽略不计;场地条件对上部结构响应有一定影响,表现为场地土越软,结构响应越大,但这一影响总体上随着归一化地面峰值加速度的增大而减小;对于给定的场地类别、质量比和归一化地面峰值加速度,归一化峰值伪加速度基本服从正态分布。基于参数分析结果,建立了归一化峰值伪加速度平均值与变异系数的简化计算公式,公式计算结果与简化模型计算结果吻合较好,可用于计算任意超越概率下的归一化峰值伪加速度值。     

某滑坡成因机理及稳定性分析

分别介绍了某滑坡的基本特征和变形特征及滑坡后缘滑动面的基本特征,对引起滑坡蠕动变形的主要因素进行了分析,通过对滑坡稳定性进行计算,作出了滑坡灾害预测,并得出了相关结论。     

Torsional response of base-isolated structures due to asymmetries in the superstructure

The torsional response of base-isolated structures when eccentricities are set in the superstructure is presented. Nonlinear dynamic analyses were used to study peak responses for different ratios of static eccentricities (e_s) between the center of mass and the center of rigidity for the superstructure. Unidirectional and bidirectional actions of selected ground motions typical of firm soils of the Mexican Pacific Coast were used in the study. An effective period range between 1.5 and 3.0 s (1.5 s≤T_I≤3.0 s) for the base-isolated structures was considered in the present study. Bilinear isolator systems with yield forces of 5% and 10% the weight of the complete structure (V_y/W=0.05 and V_y/W=0.10) and a postyield stiffness of 10% their elastic stiffness (k₂/k₁=0.10) were considered. Peak dynamic responses such as maximum isolator displacements and peak displacement ductility demands were studied and compared to the ones obtained for symmetric systems of reference for the different ground motions under consideration, assessing the importance of the relative value of e_s on those response quantities.     

Seismic performance of an immersed tunnel considering random soil properties and wave passage effects

This paper presents the results of the dynamic finite element analysis of the Hong Kong–Zhuhai–Macau immersed tunnel, conducted to study the effects of the random soil properties and the wave passage effect. According to the results of the free-field analysis, it was found that the wave passage effect could decrease peak ground acceleration (PGA) and causes a time lag in wave arrivals. Conversely, the random soil properties enlarge PGA sharply. The ‘low-frequency amplification, high-frequency filter’ phenomenon also occurs. The results of the structural dynamic analysis indicate that the soil properties and the wave passage effect have a significant influence on dynamic responses of the immersed tunnel. Although random soil properties only alter bending moments slightly, it can enlarge axial forces by up to 230% and the deformations of Gina gaskets. The wave passage can increase bending moments, Gina gaskets deformations and especially axial forces. The inertial force is the main cause for the sharp increases in axial forces. The combined effects of the random soil properties and the wave passage effect are remarkable. In some cases, Gina gasket deformations will exceed their upper and lower limits of compression, raising the possibility of joint failure and leakage. Thus, it is necessary to consider the influences of the random soil properties and the wave passage effect when conducting a practical seismic design.     

反应堆筒体滑模变形观测方案及数据处理方法研究

本文通过对反应堆筒体滑模在施工过程中的变形特点进行分析,提出一种能准确反应滑模变形的变形观测方案及数据处理方法,并可将这种数据处理方法推广应用于大型的、类似的圆形（或圆筒形）结构的变形观测中。通过测量检查,及时发现不同程度偏差,并进行纠偏,可以确保滑模施工按质按时进行。     

南京新世纪中心顶部钢塔结构动力特性及地震响应分析

本文首先介绍了江苏省第一高楼南京新世纪中心顶部钢塔的三维模型的建立，然后通过模态分析计算了主体结构和顶部钢塔的动力特性，以及二者之间的相互影响。在此基础上采用振型分解反应谱法对钢塔在地震力作用下的响应进行了计算分析，并提出该钢塔鞭梢效应的放大系数。     

高速公路桥梁滑板支座变形的原因及防治措施

针对山区高速公路桥梁相对较多的现状,结合工程实践,对高速公路桥梁滑板支座变形的原因进行了分析,并针对性地提出了减小滑板支座变形的措施,同时简单介绍了滑板支座的更换,以解决桥梁滑板支座的变形问题.     

某水库溢洪道右边坡塌滑原因分析

某水库溢洪道施工开挖后 ,右边坡发生数次塌滑现象 ,对此运用赤平极射投影分析和成因历史分析的方法 ,对边坡滑塌的客观原因和主观原因进行了分析 ,以引起对边坡塌滑的足够重视。     

Seismic performance and collapse prevention of concrete-filled thin-walled steel tubular arches

The primary objective of this paper is to investigate the seismic behaviour of concrete-filled steel tubular (CFST) arches using incremental dynamic analysis (IDA). A nonlinear elastic–plastic finite element model is developed using OpenSees software and is verified with a shaking table test. Single-record IDA studies indicate that a CFST arch undergoes global dynamic instability when subjected to ground motions of increasing intensity levels. During this process, either dynamic elastic buckling or dynamic elastic–plastic buckling may occur. Dynamic strength, which is defined as the capacity for preventing global dynamic instabilities of CFST arches, is determined with a series of multi-record IDA calculations. A lower bound equation that takes into account the effect of slenderness ratio, axial compression ratio, and included angle is proposed for the prediction of the dynamic strength of CFST arches.     

地震作用下饱和回填砂土重力式挡土结构滑动与转动位移分析

 预测地震作用下重力式挡土结构的位移是基于位移抗震设计方法的关键。基于Newmark滑动理论、超孔隙水压力应力模型和累积损伤原理,建立饱和回填砂土中超孔压比时程计算模型,以及墙体滑动和转动临界加速度时程计算模型。基于所建立的模型,提出用于计算饱和回填砂土重力式挡土结构滑动和转动位移的计算方法。采用该方法,分析土体参数和地震动参数对墙体滑动及转动位移的影响,并对墙体滑动与转动的耦合作用进行研究。结果表明,填土不发生液化的情况下,滑动位移对土体相对密度和墙体与地基土间的摩擦角十分敏感;转动位移对输入地震的震级、水平加速度和竖向加速度、填土的内摩擦角、墙背摩擦角和相对密度均较为敏感。超孔隙水压力对墙体滑动和转动位移的影响不可忽视。在地震作用下墙体与墙后填土破坏土楔体共同运动的假设条件下,墙体滑动与墙体转动相互抑制。     

建筑结构轻钢屋面板抗震试验和加固

对9个轻钢屋面板试件进行试验研究,以评估其抗震性能。根据当前的隔板设计方法,隔板能够提高承受动力荷载的剪切强度,而不是剪切刚度。此外,随着振幅增大,剪切刚度降低。使用较厚的面板或面板的安装方向与荷载方向平行时,隔板延性将降低。大多数损坏的隔板维修后可达到其初始强度,抗震加固措施能够有效增加电弧点焊/按钮冲隔板的剪切强度和刚度。     

地震作用下钢框架混凝土核心筒组合结构体系的抗震性能

钢框架混凝土核心筒组合结构体系是外框架采用钢结构,内筒采用混凝土剪力墙结构,形成钢框架混凝土内筒体系。采用ANSYS有限元软件对25层钢框架混凝土核心筒组合结构体系进行地震作用下的地震响应分析和稳定性分析,得到数据结果表明,该结构体系抗震性能比纯钢框架架结构的抗震性能更加优越。     

罕遇地震作用下高架桥抗震性能评估与加固

为了评估罕遇地震作用下高架桥的抗震性能,提出了一套抗震性能评估流程并对一座在役高架桥进行评估.首先建立了高架桥非线性动力时程分析模型;然后进行了模态分析,在综合考虑了有效质量系数和振型图后,选取了用于计算Rayleigh系数的参考振型;最后对动力时程分析结果中各墩的弯曲变形能力和抗剪强度进行评估,并根据评估结果提出了加...