Shaking table test and analysis method on ultimate behavior of slender base‐isolated structure supported by laminated rubber bearings     

Eiji Takaoka  Arinori Nimura 《地震工程与结构动力学》2011,40(5):551-570

This paper describes the results of shaking table tests to ascertain the ultimate behavior of slender base‐isolated buildings and proposes a time history response analysis method, which can predict the ultimate behavior of base‐isolated buildings caused by buckling fracture in laminated rubber bearings. In the tests, a base‐isolated structure model weighing 192 kN supported by four lead rubber bearings is used. The experimental parameters are the aspect ratio of height‐to‐distance between the bearings and the shape of and the axial stress on the bearings. The test results indicate that the motion types of the superstructure at large input levels can be classified into three types: the sinking type; the uplift type; and the mixed type. These behaviors depend on the relationship between the static ultimate lateral uplifting force on the superstructure and the lateral restoring characteristics of the base‐isolated story. In the analysis method, bearing characteristics are represented by a macroscopic mechanical model that is expanded by adding an axial spring to an existing model. Nonlinear spring characteristics are used for its rotational, shear, and axial spring. The central difference method is applied to solve the equation of motion. To verify the validity of the method, simulation analysis of the shaking table tests are carried out. The results of the analysis agree well with the test results. The proposed model can express the buckling behavior of bearings in the large deformation range. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

高层隔震结构扭转分析   总被引：2，自引：0，他引：2  

祁皑  商昊江  范宏伟 《世界地震工程》2011,27(1)

为研究高层隔震结构在地震作用下的扭转效应,用Etabs软件建立1个高层抗震结构和4个具有不同扭转特性的高层隔震结构的空间模型进行地震响应分析,以验证此原则上部结构质量中心与隔震层刚度中心的重合与否对结构扭转效应的影响程度,而后考察偏心高层隔震结构在偶然偏心地震作用下结构的扭转效应。结果表明:由于地震作用的减小,扭转效应要远小于原抗震结构,且隔震本身对于结构扭转效应的抑制效果要好于上述原则;扭转效应的减震率大于平动效应的减震率。布置在隔震层平面外围的铅芯橡胶隔震支座对隔震层的扭转有一定的控制作用。  相似文献   

Numerical simulation of the seismic behavior of self-centering steel beam-column connections with bottom flange friction devices     

Tong Guo  Lianglong Song  Guodong Zhang 《地震工程与工程振动(英文版)》2011,10(2):229-238

A new type of steel moment resisting frame with bottom ? ange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthquakes. This paper presents a numerical simulation of self-centering beam-column connections with BFFDs, in which the gap opening /closing at the beam-column interfaces is simulated by using pairs of zero-length elements with compression-only material properties, and the energy dissipation due to f...  相似文献   

Experimental research on horizontal bearing behavior of caisson-pile composite foundationEI北大核心CSCD     

Wang Lei  Guo Chao  Mu Bao-gang  Gong Wei-ming  Sun Zhen-wei 《岩土力学》2015,(11):3150-+

In this study, four groups of different types of bridge foundation model are tested to research the horizontal bearing behavior of caisson-pile composite foundation in lab based on the Qiongzhou Strait bridge project. The Q-s curve and horizontal ultimate bearing capacity of these four groups of foundations in sandy soil layer are obtained. Pile bending moment and shear force of pile shaft are analyzed in detail. At the same time, the load sharing ratio of caisson and piles is discussed. The results show that the horizontal ultimate bearing capacities of a single caisson foundation are increased by 1.2 times, 1.6 times and 2 times respectively with adding skirts, steel pipe pile, or steel pipe pile and the skirt. The maximum bending moment point is in the middle of the pile shaft, i.e. at about 0.5 m under the mud surface. The horizontal load is borne mainly by the upper caisson foundation and soil layers above the middle upper part of pile. The maximum shear force is found at the joint of pile top of steel pipe and caisson pile, where the reinforcement measures should be taken in practical engineering. The research achievements could provide a better reference for design or construction of caisson-pile composite foundation.  相似文献   

竖向高荷载作用下大直径超长钻孔灌注桩承载性能试验     

桑伟锋 《世界地质》2020,39(1):127-134

通过机场—西华高速大直径超长钻孔灌注桩大吨位竖向单桩静载试验,分析了该地区大直径超长钻孔灌注桩的承载性状以及荷载传递机理。试验结果表明:试桩的Q-S曲线呈缓变型,桩端承载力占总荷载的比例均<10%,即均表现为摩擦桩特性;试桩的侧摩阻力自上而下逐步发挥,侧摩阻力和桩端阻力异步发挥且互相耦合;大直径超长钻孔灌注桩桩侧摩阻力的发挥与土层性质、土层埋深及桩顶荷载水平有关;在高荷载作用下桩侧上部土层摩阻力具有不同程度的软化现象,而中下部土层侧摩阻力具有不同程度的强化现象,甚至即使在最大加载情况下,桩身下部土层的侧摩阻力也并未完全发挥,因此在根据规范计算超长桩承载力时,不同深度土层的侧摩阻力应乘以相应不同的修正系数。  相似文献   

基于简化力学模型的隧道锚极限承载力估值公式     

王东英  汤华  尹小涛  杨光华  姜燕 《岩土力学》2020,41(10):3405-3414

悬索桥隧道式锚碇的设计理念为锚碇夹持岩体协同承载，因而承载能力远超同体积的重力式锚碇。但因目前对围岩协同作用认识尚不充分，在当前隧道式锚碇设计中仍保守地忽略锚碇和岩体间的挤压效应。为弄清锚碇?岩体协同承载的机制，揭示隧道锚承载能力提高的本质，通过分析隧道式锚碇建设至成桥全过程受力，建立隧道锚的简化力学模型，并引用Mindlin应力解分析了荷载沿锚碇轴向的传递规律以及荷载产生的作用于锚碇?岩体间的挤压应力分布，最终给出了隧道式锚碇极限承载力的简化估算方法，并通过伍家岗大桥隧道锚工程实例分析了结果的合理性。所得结论主要有：锚碇?岩体界面力主要由锚碇自重和锚碇?岩体相互挤压产生；锚碇?岩体界面附加应力自后锚面向前锚面呈先增后减的变化趋势，在距后锚面约1/3L处达到应力峰值；以容许抗剪强度为破坏判据解得的伍家岗长江大桥隧道式锚碇的极限承载力为3 504 MN，约为16倍的设计荷载，与室内试验值基本吻合。  相似文献   

海上风机吸力式桶形基础承载特性研究综述     

毋晓妮  廖倩  李晔 《海洋技术学报》2020,39(1):91-106

风机基础作为海上风机整体结构的重要组成部分,承受着上部风机所受到的风浪流荷载,并且对风机的安全性及可靠性至关重要。吸力式桶形基础由于其安装简单和可重复利用等优点,在海洋平台基础中得到了广泛应用,并逐步应用于海上风机基础中。但由于海上风机与海洋平台在海洋环境中的荷载工况有一定的差别,仍需要通过对其承载特性研究现状进行全面认识,以实现吸力式桶形基础在海上风机基础中的可靠应用。文中通过总结和评价现有研究对桶形基础在不同土体条件以及荷载条件下进行试验及数值模拟分析得到的研究结果,综述了静荷载和循环荷载作用下砂土和黏土中的吸力式桶形基础的承载特性研究现状,以及海上风机吸力式桶形基础的相关研究。文章展望了目前应用于海上风机基础的桶形基础仍缺乏的研究,为海上风机吸力式桶形基础的可靠应用及后续研究提供重要参考。  相似文献   

高压旋喷桩单桩承载力分析     

王勃  行小盈 《岩土工程技术》2020,(1):48-52

高压喷射注浆于1968年首创于日本。我国于20世纪70年代初相继引进并开始研究高压喷射注浆技术。目前,高压旋喷工艺应用最为广泛,工艺技术最为成熟。对旋喷桩成桩质量及单桩承载力进行研究分析,为旋喷桩在地基与基础工程、水利水电工程、止水、加固工程中的应用提供设计参考依据。该试验在陕西省延安市某建成小区内选三个试验点,按不同旋喷桩施工工艺成桩,通过对桩身完整性检测、单桩承载力试验,分析旋喷桩成桩质量及单桩承载力。  相似文献   

New P–T constraints on the Tamayen glaucophane‐bearing rocks,eastern Taiwan: Perple_X modelling results and geodynamic implications          下载免费PDF全文

I. Baziotis  C.‐H. Tsai  W. G. Ernst  B.‐M. Jahn  Y. Iizuka 《Journal of Metamorphic Geology》2017,35(1):35-54

New pseudosection modelling was applied to better constrain the P–T conditions and evolution of glaucophane‐bearing rocks in the Tamayen block of the Yuli belt, recognized as the world's youngest known blueschist complex. Based on the predominant clinoamphibole, textural relationships, and mineral compositions, these glaucophane‐bearing high‐P rocks can be divided into four types. We focused on the three containing garnet. The chief phase assemblages are (in decreasing mode): amphibole + quartz + epidote + garnet + chlorite + rutile/titanite (Type‐I), phengite + amphibole + quartz + garnet + chlorite + epidote + titanite + biotite + magnetite (Type‐II), and amphibole + quartz + albite + epidote + garnet + rutile + hematite + titanite (Type‐III). Amphibole exhibits compositional zoning from core to rim as follows: glaucophane → pargasitic amphibole → actinolite (Type‐I), barroisite → Mg‐katophorite/taramite → Fe‐glaucophane (Type‐II), glaucophane → winchite (Type‐III). Using petrographic data, mineral compositions and Perple_X modelling (pseudosections and superimposed isopleths), peak P–T conditions were determined as 13 ± 1 kbar and 550 ± 40 °C for Type‐I, 10.5 ± 0.5 kbar and 560 ± 30 °C for Type‐II (thermal peak) and 11 ± 1 kbar and 530 ± 30 °C for Type‐III. The calculations yield higher pressures and temperatures than previously thought; the difference is ~1–6 kbar and 50–200 °C. The three rock types record similar P–T retrograde paths with clockwise trajectories; all rocks followed trajectories with substantial pressure decrease under near‐isothermal conditions (Type‐I and Type‐III), with the probable exception of Type‐II where decompression followed colder geotherms. The P–T paths suggest a tectonic environment in which the rocks were exhumed from maximum depths of ~45 km within a subduction channel along a relative cold geothermal gradient of ~11–14 °C km^?1.  相似文献   

Soil‐pile interaction in the pile vertical vibration considering true three‐dimensional wave effect of soil     

W.B. Wu  K.H. Wang  Z.Q. Zhang  Chin Jian Leo 《国际地质力学数值与分析法杂志》2013,37(17):2860-2876

The dynamic response of an end bearing pile embedded in a linear visco‐elastic soil layer with hysteretic type damping is theoretically investigated when the pile is subjected to a time‐harmonic vertical loading at the pile top. The soil is modeled as a three‐dimensional axisymmetric continuum in which both its radial and vertical displacements are taken into account. The pile is assumed to be vertical, elastic and of uniform circular cross section. By using two potential functions to decompose the displacements of the soil layer and utilizing the separation of variables technique, the dynamic equilibrium equation is uncoupled and solved. At the interface of soil‐pile system, the boundary conditions of displacement continuity and force equilibrium are invoked to derive a closed‐form solution of the vertical dynamic response of the pile in frequency domain. The corresponding inverted solutions in time domain for the velocity response of a pile subjected to a semi‐sine excitation force applied at the pile top are obtained by means of inverse Fourier transform and the convolution theorem. A comparison with two other simplified solutions has been performed to verify the more rigorous solutions presented in this paper. Using the developed solutions, a parametric study has also been conducted to investigate the influence of the major parameters of the soil‐pile system on the vertical vibration characteristics of the pile. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献