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1.
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｉｍｐａｃｔｏｎｐｉｌｅｓ ｂｒｉｄｇｅｓｔｒｕｃｔｕｒｅｓｂｙｍｏｖｉｎｇｓｈｉｐｓｏｒｏｔｈｅｒｄｒｉｆｔｉｎｇｏｂｊｅｃｔｓｏｆｔｅｎｄｅ ｓｔｒｏｙｓｔｈｅｂｒｉｄｇｅ,ｓｏｉｔｉｓｉｍｐｏｒｔａｎｔｔｏｓｔｕｄｙｔｈｅ 相似文献
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陈国周林智勇林文彬 《福建工程学院学报》2019,(6):518-523
针对水平受荷桩刚度系数的传统计算公式复杂、计算量大的缺点,使用桩顶嵌固的边界条件推导出水平受荷桩刚度系数新的表达式。采用幂级数证明了新解法与传统方法是等价的,并通过算例验证了两种方法得到的刚度系数是相同的。对刚度系数的影响因素分析表明,桩径对刚度系数影响较大,其中水平刚度系数近似按桩径的两次方进行增长,转动刚度系数近似按桩径的三次方进行增长。土体m值对刚度系数也有一定的影响,其中水平刚度系数按m值的0.6次幂进行增长,转动刚度系数按m值的0.4次幂进行增长。 相似文献
3.
借助Plaxis 2D的有限元分析程序,计算不同支撑刚度下的支护桩变形及内力,揭示了支护桩支撑轴力与支撑刚度之间的变化规律,分析了两者比值对支护桩的影响曲线,并得出近似比值,用以指导工程实际。 相似文献
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INTRODUCTIONInterestinonedimensionalwavepropagationtheoryforapplicationtounderstandingpiledriv ingismorethanacenturyold .ImportantworkdirectlyrelatedtocurrentapplicationstopiledrivabilitystartedshortlyaftertheSecondWorldWarandcontinuedtothepresent,assuchp… 相似文献
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In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load. 相似文献
6.
In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load. 相似文献
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Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method. 相似文献
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为研究拱型波纹屋盖在脉动风作用下的应力风振系数,考虑不同跨度、支座、不同矢跨比对应力风振系数的影响,利用ANSYS有限元分析软件对18 m、30 m跨波纹拱进行水平及竖向脉动风作用下的风振响应分析,得到了结构在不同位置处节点的应力及应力风振系数.计算结果表明:波纹拱应力风振系数随着结构的跨度增大而增大,随着矢跨比的增加而增加,支座约束为固支波纹拱的风振系数小于铰支波纹拱.该结论为结构设计、施工及同类型大跨轻型屋盖的风致振动提供参考和借鉴. 相似文献
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潘海龙 《石家庄铁路职业技术学院学报》2021,(1):62-66,83
为解决传统桩基承载力低的问题,基于差异沉降控制优化设计桩基。分析桩基设计存在的问题,主要包括:桩基支承刚度设定误差高、桩基差异沉降大、桩基结构设计不合理,通过设定桩基支承刚度,控制桩基差异沉降,采用桩基塌孔承桩断裂结构,实现对桩基的优化设计。设计实例分析,结果表明,设计的桩基承载力明显高于对照组,能够解决传统桩基承载力低的问题。 相似文献
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欧智菁俞杰林上顺王金泽 《福建工程学院学报》2019,(6):511-517
以黄桷湾特大桥为工程背景,选取轴压比、梁墩刚度比、系梁布置形式及柱肢混凝土强度等级为设计参数,应用Midas Civil有限元软件构造了20座三跨对称桥梁计算模型。研究E1地震作用下钢管混凝土双肢格构墩连续梁桥主要控制截面参数地震响应,探讨各设计参数对钢管混凝土双肢格构墩连续梁桥抗震性能的影响规律,并对全桥进行优化验证。研究结果表明:轴压比对地震作用下结构内力和位移有一定影响,建议控制在0.15~0.25;梁墩刚度比对结构的抗震性能影响较大,控制在4.08~10.90时结构的内力分布更加合理;核心混凝土的强度在C40~C50时取值较为合理。 相似文献
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为了研究移动荷载下路面结构内部细观结构的响应,采用离散元方法进行了多尺度路面结构移动荷载响应的分析．建立了柔性基层沥青路面典型结构的离散元模型,并计算了移动荷载作用下沥青层底的应力和应变,通过与已有经典计算程序荷栽响应计算结果的比较,验证了所建立的离散元模型．以该离散元模型为基础,在沥青混凝土结构层的底部,采用尺度较小的离散单元描述粗集料的体积含量、分布特征以及空隙大小等细观结构,以此建立路面结构的多尺度模型．对路面结构宏观响应与细观结构的荷载响应进行了比较分析,并分析了沥青砂浆劲度对细观结构处荷载响应的影响．结果表明：粗集料与沥青砂浆界面位置的拉应力均值和离散系数均大于沥青砂浆内部;荷载引起的应力和应变在沥青砂浆内部和界面内部均存在不均匀分布;沥青砂浆的劲度越大,沥青混凝土内部的荷载响应分布越趋于均匀． 相似文献
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FOR THE GEO一TEEHNIEAL DESI，PARAMETERS OF 5011，EOMPARISON OF SEISMIE RESPONSES BASED ON DIFFERENT THE UNEVEN DISTRIBUTION OF THE DIFFERENT KINDS OF 5011 METHODS TO EVALUATE THE 5011 FUNETIONS.IN ADDITION， AND SAMPLING LOCATIONS DURING EXPLORATION AND I… 相似文献
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ZHU Bin LEUNG A.Y.T. 《浙江大学学报(A卷英文版)》2006,7(8):1351-1357
INTRODUCTION Thin-walled structures have considerable tech-nological importance in many situations of engi-neering practice. The rotary and warping inertia terms should be considered in the analyses of thin-walled structures (Alwis and Wang, 1996), although it is difficult to obtain the analytical solutions of govern-ing differential equations, especially of thin-walled frame and spatial twisted structure. The finite element method (FEM) is widely used for vibration and sta-bility analy… 相似文献
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Jia-jin Zhou Xiao-nan Gong Kui-hua Wang Ri-hong Zhang Jia-jia Yan 《浙江大学学报(A卷英文版)》2017,18(11):895-909
The pre-bored grouting planted nodular (PGPN) pile is a type of composite pile foundation that is considered to be environmentally friendly and economical. A simplified approach, which considers the two interfaces of the pile shaft, was proposed to analyze the load-displacement response of a single PGPN pile. An elastic-failure model, based on the shear test results, was used to simulate the shearing behavior of the concrete-cemented soil interface. A hyperbolic nonlinear model, considering the influence of cement paste injection, was created to simulate the behavior between the skin friction and the relative displacement developed along the cemented soil-soil interface. A linear model and a nonlinear model that considers the reduction in the shearing stiffness were used to simulate the PGPN pile base load-displacement responses in a field test and in a model test, respectively. Comparisons between the calculated and measured load-displacement responses revealed relatively good agreement. The proposed approach is thus shown to be efficient and suitable for the analysis of a single PGPN pile embedded in layered soils, and is used to analyze the factors influencing its behavior. Enlarged cemented soil base is considered to be effective in promoting the behavior of a short PGPN pile, while increasing the diameter of cemented soil along the shaft is efficient in promoting the compressive bearing capacity of a long PGPN pile. 相似文献
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Shaking table test of pile-water-pier superstructure 总被引：1，自引：1，他引：0
The model test of seismic simulation shaking table is an important method to study the seismic design of bridge structure. In order to evaluate the seismic response and dynamic characteristics of pile-water-pier system for developing more reliable design procedures, shaking table model tests of a submerged bridge pier system, including pile groups-cap-pier and inertia mass, were conducted. Since different similitude laws corresponding to different test objectives affected the validity of test results, the similitude law with the aim to consider the effect of hydrodynamic pressure was proposed and confirmed through an actual example. Based on the test results, the effect of water around model on seismic response under seismic excitation input was analyzed and the failure level was judged by observing the variation of basic frequency. The test results indicate that the transfer function of analytical model with water is different from that without water, the natural frequency without water is always higher than that with water, and the first modal shapes are various. It is also concluded that the similitude law is suitable for practical application and the dynamic characteristics and seismic response of the structure system can be changed because of the existence of the surrounding water, which should be paid much attention in the further investigation. 相似文献
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基于高等数学中极值法求最值的原理,结合力学的实践特点,提出了用极值法分析任意动力荷载作用下动力系数反应谱的思想。以线性渐增荷载为例,介绍了极值法求解动力反应的过程,推导了在动力荷载作用下的动力系数与动荷载时间比值之间的函数关系式。结果表明该方法能有效地进行结构动力学强迫振动部分的动力反应分析,同时也方便了教师的教学和学生的自学,对提高该课程的教学质量,帮助学生提高自主学习能力都有重要的意义。 相似文献
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赵娟娟 《天津职业院校联合学报》2013,15(2):44-48
文章以山东济南建邦三塔斜拉桥为研究对象,采用有限元软件建立该桥有桩和无桩两种模型,进行了动力特性分析,并在不同工况下进行反应谱和弹性时程分析。两种模型的地震响应的结果表明,桩土效应对结构位移和内力影响较大,在对大跨度支撑体系斜拉桥进行抗震分析时,应该考虑桩土效应。 相似文献
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考虑阻尼之组合结构的动内力局部效应修正 总被引：2，自引：1，他引：1
以往对结构进行动力分析常常忽略局部效应的影响,但实践证明,局放效应在某些结构中占有很大的比重,为得到精确的动力响应,必须考虑局部效应本文在已有的基础上,提出了考虑阻尼之组合结构在地震作用下局部效应的计算方法通过对结构动内力进行局部效应修正前后求解精度的对比,证明了考虑局部效应的重要性．最后,本文对核反应堆堆顶屏蔽给构进行了局部动内力分析,得出了一些有意义的结论。 相似文献
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Dynamic characteristics analysis of a misaligned rotor-bearing system with squeeze film dampers 总被引：1，自引：0，他引：1
In this paper, a dynamic model is established for a two-stage rotor system connected by a gear coupling and supported on ball bearings with squeeze film dampers (SFDs). The nonlinear dynamic behavior of the rotor system is studied under misalignment fault condition. The meshing force of the gear coupling is calculated considering the deformation of the tooth caused by torque transmission and dynamic vibration. The contact force between the ball and race is computed based on the Hertzian elastic contact deformation theory and the elastohydrodynamic lubrication theory. The supported force of SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion are rewritten in non-dimensional differential form, and the fourth-order Runge-Kutta method is employed to solve the nonlinear dynamic equilibrium equations iteratively. To verify the validity of the dynamic model and the correctness of the numerical solution method, the experimental power spectra of the rotor system under various misalignment degrees are compared with the analytical results. The effects of several important parameters, such as the lubrication of the ball bearing, the centralizing spring stiffness, the radial clearance of SFD, and the misalignment of gear coupling, on the dynamic characteristics of the rotor system are investigated and discussed mainly focusing on the system stability. The response spectra, bifurcation diagrams, and Pointcaré maps are analyzed accordingly. These parametric analyses are very helpful in the development of a high-speed rotor system and provide a theoretical reference for the vibration control and optimal design of rotating machinery. 相似文献