高承台钢管桩受压稳定性的试验研究和数值分析     

贾强  郑爱萍  张鑫 《岩土力学》2011,32(6):1736-1740

利用微型钢管桩进行基础托换是既有建筑物地下增层改造的有效方法。钢管桩的下端插入到混凝土桩头内,上端与托换承台相连,桩四周的土方开挖后稳定性降低,其受压极限承载力无法按现行规范求出。分别用1:2模型试验和非线性屈曲数值分析的方法得到了钢管桩顶部受压的应力分布和极限承载力,并进一步确定出其计算长度系数和受压稳定性系数。用模型试验求得钢管桩受压稳定性的计算长度系数为0.616,数值分析的结果为0.683,此时钢管处于底端固定、顶端铰接的约束状态。用数值分析得到的钢管桩受压极限承载力偏安全,可为工程设计提供参考  相似文献   

风雪共同作用下膜结构雪压分布规律的数值模拟研究     

孙芳锦  殷志祥 《地震学刊》2010,(1):83-87

对膜结构在风雪共同作用下的雪压分布规律进行了数值模拟研究。首先采用两相流原理对雪漂运动中的空气相和雪相分别进行了数值建模,然后采用CFD数值模拟技术,研究了在风雪共同作用下双坡型膜结构表面的雪荷载分布规律,分析了双坡型膜结构的重要几何参数变化时,雪漂及屋面雪荷载分布的变化规律,总结了双坡型膜屋面在风雪共同作用下的雪压分布规律。结果表明,屋面倾角和屋面宽度是影响风雪共同作用下膜结构表面雪压分布的重要因素,檐口高度和屋面长度是影响膜结构表面雪压分布的次要因素。本文研究为更安全、经济地进行膜结构的抗风雪设计、施工提供了可靠的科学依据。  相似文献   

模卡式节能墙体钢框架体系滞回性能研究     

王凤池  李中原  朱浮声  王声平  叶霄鹏 《世界地震工程》2010,26(1)

设计制作了内填充榫卯砌块墙体的钢框架,对体系施加低周水平往复荷载。在往复荷载的作用下,在榫卯节点连接处产生了应力集中,榫头的上部边缘发生剪切破坏,使得插孔处混凝土被压碎,最终导致墙体与连接件发生脱离而体系破坏。开裂后,滞回曲线由梭形向弓形、反S形变化,开裂荷载约为极限荷载的48%,大于同类钢框架填充墙体的比值。说明榫卯结构改善了墙体的变形能力,在墙体达到极限荷载后,可保持裂而不倒。体系的能量耗散系数、等效粘滞阻尼比和延性优于普通填充墙体,说明榫卯结构提高了墙体的耗能能力进而提高了抗震能力。  相似文献   

盆地深部穹隆构造发育特征、成因机制及石油地质意义——以塔里木盆地顺北地区为例   总被引：1，自引：0，他引：1  

高天  邓尚  李海英  刘雨晴  黄诚  艾合买提江·阿不都热和曼 《地质论评》2022,68(1):217-232

塔里木盆地顺北地区奥陶系碳酸盐岩中广泛发育穹隆构造.为研究盆地深部穹隆构造的发育特征、成因机制及石油地质意义,基于顺北地区高精度三维地震资料,对穹隆构造开展几何学定量解析,确定其空间分布规律及内部结构样式;结合区域构造背景及盆内构造发育特征,明确其成因机制;在此基础上,结合生产动态数据探讨穹隆构造的控储—控藏作用.研究...  相似文献   

Turbulence fields in the lee of two‐dimensional transverse dunes simulated in a wind tunnel     

Zhibao Dong  Guangqiang Qinan  Ping Lu  Wanyin Luo  Hongtao Wang 《地球表面变化过程与地形》2009,34(2):204-216

The turbulence field of airflow in the lee of a dune has significant impacts on dune dynamics and related processes. We used particle image velocimetry in a wind tunnel simulation to obtain detailed velocity measurements in the lee of two‐dimensional transverse dune models, then used the results to analyse their turbulence fields. The dune models used in this study had a single lee angle of 30°, and a total of six stoss angles: 3°, 5°, 10°, 15°, 20° and 25°. We used vorticity, turbulence intensity, Reynolds stress and turbulent kinetic energy to characterize the turbulence fields. These parameters were functions of stoss angle, wind velocity, distance from the dune crest and height above the ground surface. The stoss angles could generally be divided into two groups based on the profiles of mean velocity, turbulence and Reynolds stress. Stoss angles of 3° and 5° usually had similar profiles, and angles of 15°, 20° and 25° formed a second group with similar profiles. The profiles for the stoss angle of 10° were usually transitional and were intermediate between the two groups. Vorticity, Reynolds stress and turbulent kinetic energy increased monotonically with increasing free‐stream wind velocity, but their variations with respect to the stoss angle were complex. The stoss angles of 15° and 20° had the maximum values of these three parameters, thus these angles may have special significance in dune development given the characteristics of the mean velocity fields and turbulence fields they produce within the lee airflow. It is the streamwise velocity component and its turbulence that determine the surface shear stress. Copyright © 2008 John Wiley and Sons, Ltd.  相似文献   

Hybrid simulation of a zipper‐braced steel frame under earthquake excitation     

T. Y. Yang  B. Stojadinovic  J. Moehle 《地震工程与结构动力学》2009,38(1):95-113

Hybrid simulation is a testing methodology that combines laboratory and analytical simulation to evaluate seismic response of complex structural framing systems. One or more portions of the structure, which may be difficult to model numerically or have properties that have not been examined before, are tested in one or more laboratories, whereas the remainder of the structure is modeled in software using one or more computers. These separate portions are assembled such that combined dynamic response of the hybrid model to excitation is computed using a time‐stepping procedure. A hybrid simulation conducted to examine the seismic response of a type of steel concentrically braced frame, the suspended‐zipper‐braced frame, is presented. The hybrid simulation testing architecture, hybrid model, test setup, solution algorithm, and the seismic response of the suspended‐zipper‐braced frame hybrid model are discussed. Accuracy of this hybrid simulation is examined by comparing hybrid and computer‐only simulations and the errors are quantified using an energy‐based approach. This comparison indicates that the deployed hybrid simulation method can be used to accurately model the seismic response of a complex structural system such as the zipper‐braced frame. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Investigation of the sliding behavior between steel and mortar for seismic applications in structures     

Jason McCormick  Takuya Nagae  Masahiro Ikenaga  Peng‐Cheng Zhang  Mika Katsuo  Masayoshi Nakashima 《地震工程与结构动力学》2009,38(12):1401-1419

The friction developed between a steel base plate and a mortar base contributes shear resistance to the building system during a seismic event. In order to investigate the possible sliding behavior between the base plate and the mortar, a shake table study is undertaken using a large rigid mass supported by steel contact elements which rest on mortar surfaces connected to the shake table. Horizontal input accelerations are considered at various magnitudes and frequencies. The results provide a constant friction coefficient during sliding with an average value of approximately 0.78. A theoretical formulation of the friction behavior is also undertaken. The theoretical equations show that the sliding behavior is dependent on the ratio of the friction force to the input force. The addition of vertical accelerations to the system further complicates the sliding behavior as a result of the varying normal force. This results in a variable friction resistance which is a function of the amplitude, phase, and frequency of the horizontal and vertical input motions. In general, this study showed a consistent and reliable sliding behavior between steel and mortar. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

方形组合式钢丝绳隔震器静刚度试验研究     

卢红标  赵帆  蔡立艮  严东晋 《地震学刊》2009,(5):537-540

作者研制了一种新型方形组合式钢丝绳隔震器。该种隔震器由4个条形夹具夹持16根普通镀锌钢丝绳组合而成,从结构形式上保证了水平刚度对称。经过多次垂直向循环静力加卸载试验,运用Origin 7.0软件对实验数据进行分析处理,绘制出该种隔震器的静力特性曲线,并分别与目前防护工程中采用的条形不锈钢钢丝绳隔震器、鼓形钢丝绳隔震器的静力特性曲线进行了比较。试验结果表明,方形组合式钢丝绳隔震器不但具有初始刚度大、软特性明显、阻尼大、加工简便、性价比高等优点,而且克服了条形不锈钢钢丝绳隔震器价格高、水平刚度不相同和鼓形钢丝绳隔震器加工复杂的不足,在今后的防护工程隔震技术中有良好的应用前景。  相似文献   

不同R-μ-T关系对比研究及其在高层混合结构位移需求估计中的应用   总被引：1，自引：1，他引：0  

黄志华  吕西林  周颖  卜一 《地震工程与工程振动》2009,29(2)

本文结合弹塑性反应谱的研究,给出了求解钢框架一钢筋混凝土核心筒混合结构位移需求的基本步骤,并采用不同的R-μ—T关系计算了某15层混合结构的位移需求。结果表明：选取不同模型计算所得的位移需求有一定的偏差,偏差大致在25％以内,其中Newmark＆Hall模型会较大幅高估结构的位移需求。通过比较,本文最终选取吕西林、周定松模型,其估计的位移需求与弹塑性时程分析结果的偏差基本控制在30％以内,可以为工程界接受。对比分析不仅表明了选取该模型的合理性,同时说明弹塑性反应谱法是一种比较有效的估计此类结构位移需求的方法,在混合结构基于性态的抗震设计中具有应用价值。  相似文献   

准噶尔盆地西北缘冲断构造新解          下载免费PDF全文

孟家峰郭召杰  方世虎 《地学前缘》2009,16(3):171-180

摘要：准噶尔盆地西北缘最重要的构造特征是发育一组冲断构造。对这组冲断构造的冲断时限和冲断性质的认识不同,导致对准噶尔盆地的属性存在断陷盆地与前陆盆地之争。西北缘花岗岩及其中发育的岩墙群的精确年龄限定了研究区在314～255 Ma中处于伸展状态。西北缘侏罗系沉积范围较三叠系广,早侏罗世发育碱性玄武岩,这些都表明准噶尔盆地在侏罗纪处于伸展阶段,盆地范围不断扩大。西北缘晚三叠世地层不整合覆盖于花岗岩之上,这种现象将本区冲断构造发生的时间限定为晚二叠世至早三叠世,最晚不超过晚三叠世。在地震资料解释的西北缘剖面上,冲断构造的前缘二叠纪地层平缓且厚度稳定。西北缘二叠系发育火山岩,沉积层序具从下到上粒度由粗变细的正旋回沉积特征,沉积速率稳定,沉降曲线由陡变缓,且古地温梯度和大地热流值均较高。西北缘的圈闭类型以岩性地层等非构造圈闭为主,以构造 岩性圈闭为辅。笔者认为西北缘冲断构造的性质是在314～255 Ma伸展阶段与侏罗纪伸展阶段之间发育的一次短期反转构造,发育基底卷入的高角度冲断带,并非大规模与造山作用相关的前陆冲断带。  相似文献