共查询到19条相似文献，搜索用时 156 毫秒
1.
传统边坡可靠度分析往往在岩土参数服从线性Mohr-Coulomb（简称线性M-C）破坏准则的假设条件下进行,并且常常采用极限平衡法或有限元法计算安全系数。然而,岩土介质破坏准则具有一定的非线性。为能更加实际地描述岩土破坏机理和得到严格精确的解,基于非线性Mohr-Coulomb（简称非线性M-C）破坏准则,结合极限分析上限法和蒙特卡洛法,进行边坡可靠度上限分析。当非线性参数m=1时,与等效的线性M-C破坏准则进行对比计算,验证了方法的可行性。同时,将初始粘聚力、内摩擦角arctan（c0/σt）和非线性参数作为随机变量且服从截断正态分布,进行了参数变异性和敏感性影响分析。研究表明：非线性M-C破坏准则下,边坡可靠度随初始粘聚力、内摩擦角arctan（c0/σt）和非线性参数变异性的增大而减小;边坡可靠度随初始粘聚力和内摩擦角arctan（c0/σt）的增大而增大,随非线性参数的增大而减小。 相似文献
2.
方形高强钢管混凝土叠合柱轴压极限承载力分析 总被引：1，自引：0，他引：1
对于新提出的方形高强钢管混凝土叠合柱的极限承载力,基于统一强度理论,考虑中间主应力和材料拉压比的影响,引入有效约束系数和非有效约束系数并考虑箍筋对钢管外混凝土约束作用的不同,把钢管外箍筋约束混凝土划分为有效约束区和非有效约束区,将方形截面等效为圆形截面以考虑钢管核心混凝土受到的钢管和外围钢筋混凝土的双重约束效应,提出了方形高强钢管混凝土叠合柱的一种新的轴压极限承载力计算方法。将所得理论计算结果与文献试验结果进行对比,吻合良好,证明了公式的正确性。对各参数的影响规律分析表明,方形高强钢管混凝土叠合柱的承载力随着侧压系数、中间主应力影响系数、材料拉压比和纵向配筋率的增大而增大,随着钢管径厚比的增大而减小。 相似文献
3.
五星形桩是一种横截面异形桩,是在圆桩的基础上向内切割5个圆弧,形成截面类似五星形的异形桩。按其截面性质分为周长最大化五星形桩F1、周长面积比最大化五星形桩F2两种桩型,为掌握五星形桩的水平承载性能进行了与圆桩的对比模型试验研究。试验用土为干砂,砂雨法土样制作,模型桩为预制钢筋混凝土桩,相似比为1∶8。模型试验桩包括：五星形桩F1、五星形桩F2、与五星形桩F2截面周长相同的圆桩C1、与五星形桩F2截面面积相同的圆桩C2。由于五星形桩水平承载性能具有方向性,试验采用理论计算中水平承载力最大的方向施加水平荷载,试验结果表明：F1、C1和F2的水平极限承载力相当,但F2的截面面积最小,仅为C1的0.44倍;与C2相比,F2的水平极限承载力是其1.63倍,可见,合理截面形式的五星形桩可以提供更大的水平承载能力;五星形桩与圆桩弯矩分布规律基本一致,都在4倍直径左右（五星形桩为外接圆直径）达到最大,但五星形桩截面面积小,抗弯刚度不足,容易折断,总体水平承载性能不及截面周长相同的圆形桩,但优于截面面积相同的圆形桩。 相似文献
4.
通过对医院信息化投入、医院运营管理对医疗效益的影响规律进行分析,根据重庆市某三级甲等医院在2009-2015年间的信息化投入、医院运营管理2个方面与医疗毛收入的数据资料,通过Pearson相关分析得到医疗毛收入与11个影响指标均相关（P<0.05）,通过熵值法,选择指标权重值大于0.08的指标有医院全年财务信息化投入x1、医院全年门诊量x4、医院全年入院患者人数x6、医院全年手术量x7以及医院初级职称人数x10,其权重分别为0.190、0.086、0.085、0.084、0.084。建立多因素回归分析的数学模型,得到了指标x1、x4、x6、x7、x10与医疗毛收入拟合函数,可决系数分别为0.948 8、0.927 1、0.994 1、0.993 0、0.948 1,医疗毛收入的回归方程的可决系数为0.996 3,因此,本研究通过熵值法得到的影响医疗毛收入的5个指标,并建立得到的回归方程可应用于医院信息化投入决策的制定,为医疗卫生管理提供新的依据。 相似文献
5.
在综合分析现有水平荷载作用下桩基分析方法的基础上,建立了考虑桩侧土体受力状态的斜坡刚性桩力学模型;根据极限平衡原理,建立横向荷载作用下斜坡刚性桩弯矩和应力平衡方程;引入考虑斜坡影响的p-y曲线方法,提出了综合考虑桩侧土体极限承载力与水平抗力系数沿深度呈线性增加的侧向极限承载力与土体抗力承载力系数计算方法,同时,将该方法应用于计算实例,通过与已有有限元和理论计算方法对比分析,计算结果验证了本文方法的合理性与可行性;并利用该方法,分析了斜坡坡角、桩土接触面系数以及地基水平抗力系数对斜坡刚性桩承载特性的影响因素。分析表明:斜坡的坡角、桩土接触面系数对侧向荷载作用下斜坡刚性桩的荷载位移曲线影响明显,而桩侧土的抗力系数对侧向荷载作用下斜坡刚性桩的荷载位移曲线影响不明显。 相似文献
6.
首先介绍了复杂网络同步态的概念,以传感器量测数据为节点,定义了随时间动态变化的传感器网络,采用数学分析方法定量描述了传感器网络的动力学机制,给出了传感器网络同步态的数学定义、计算方法及其实际的物理含义。理论推导表明,同步态从全局角度评价传感器网络的健康程度,以量测数据距离关联性定义复杂网络的耦合矩阵A=（aij）N×N,并以该耦合矩阵零特征值对应的左特征向量（ξ1,ξ2,...,ξN）来刻画传感器网络节点的局部细节信息,进而衍生出基于传感器网络同步态的节点故障诊断算法,实现传感器网络的故障诊断。实验仿真了由100个传感器组成的复杂网络,采集了在稳定运动60 s期间的的量测数据,每个量测数据长度为5 000,其中有3个传感器处于间歇增益故障状态,以此来验证基于传感器网络同步态的节点故障诊断算法的有效性。结果表明,该算法不仅可以很好地跟踪整个传感器网络的工作状态,实时监测每个传感器网络节点的故障,而且可以利用传感器网络节点故障之间的相关性有效地识别出传感器量测数据的异常是由外界量测对象的改变还是由传感器本身故障引起的。该算法为全局评估传感器网络的工作状态和监测网络节点的局部故障提供了一个新颖可行的研究思路,期望为相关领域的研究学者提供有益的参考。 相似文献
7.
不同建筑热工分区办公建筑外围护结构负荷指标影响因素权重 总被引：3，自引：0，他引：3
为研究多因素对不同热工分区办公建筑总负荷指标的综合影响,在分析了单一因素对建筑总负荷指标影响规律的基础上,采用层次分析法对分别位于哈尔滨、兰州、重庆、广州的办公建筑负荷指标进行了评价。得到了窗户传热系数Kw、玻璃遮阳系数Sc、窗墙比R在不同热工分区办公建筑总负荷指标影响因素中的权重值,并对此进行了一致性检验。结果表明：对于严寒地区的哈尔滨和寒冷地区的兰州节能建筑,各因素重要程度为R > Kw > Sc;对于夏热冬冷地区的重庆和夏热冬暖地区的广州节能建筑,各因素重要程度为Sc > R > Kw。在建筑结构优化设计中应根据各热工分区负荷影响因素的比重不同进行优先控制相应因素。 相似文献
8.
建立了以容积换热系数为目标函数,工质流率U0、喷头喷孔直径di、导热油液位高度Z为决策变量的直接接触式换热器性能优化模型,同时进一步将液滴群行为与传热协同关系作为约束条件引入优化模型中,重点分析该约束条件对优化过程及结果的影响。运用遗传算法对原模型和补充模型进行了优化分析,结果表明：原模型优化后的容积换热系数达到了初始值的6.7倍;而补充模型最优值的迭代次数比原模型减小了约55%,同时最优值比原模型提高了0.3%。所以该约束条件不仅提高了迭代速率,还提高了寻求全局最优值的概率,使得最优解更逼近全局最优值。 相似文献
9.
钢管混凝土FRP混凝土（SCFC）组合柱是新近提出的一种新型组合柱形式。提出考虑外钢管与FRP的双重约束效果,采用双剪统一理论分析了SCFC组合柱外钢管、外层混凝土、FRP管以及内层混凝土的应力状态,根据静力平衡条件得到了SCFC组合柱的轴压承载力计算公式,其与试验结果能够较好吻合。分析了含钢率、FRP与钢的相对配置率、FRP径厚比以及FRP管直径对轴压承载力提高系数的影响,结果表明：随着含钢率的增加、FRP与钢的相对配置率的提高以及FRP径厚比的减小,SCFC组合柱轴压承载力提高系数都有一定程度提高;内FRP管直径与外钢管边长之比在0.65~0.75之间时,轴压承载力增益效果较好。 相似文献
10.
便利店销售额在传统零售业中增幅最高,照明在所调研样本总室内能耗中占比为43%。基于全国257家便利店的数据,探讨便利店的照明特征。采用多重线性回归方法建立照明能耗预测模型,采用因子分析方法探讨客观参数与主观评价的联系。研究表明,对便利店,考虑照明节能时需同步关注其主观评价的变化;进行照明设计时需因地制宜;照明能耗预测模型为ln y=0.479 ln x1+ 0.248ln x2-0.217（y为照明功率密度,x1为单位面积照明造价,x2为典型货架位置水平照度平均值）;顾客对照明充足度的“敏感性”比照明均匀度高;提高照度平均值有助于提高主观评价。 相似文献
11.
In order to investigate the effect of prestressed binding bars on axial compressive behavior of rectangular concrete-filled tubular (CFT) short columns, five rectangular CFT short columns, three with prestressed binding bars, one with ordinary binding bars, the other with no binding bars, were constructed and tested under axial compressive loads. The binding bars were made up with high-strength bolts. As used for ordinary binding bars, the high-strength bolts were welded to the steel tube before the column was loaded to axial compressive force. As used for prestressed binding bars, the high-strength bolts were first tensed by screwed screw cap down to bring force to prestress the steel tube and its core concrete, then welded to the steel tube before the column was loaded to axial compressive force. Test results indicate that the bearing capacity and ductility of rectangular CFT short columns are increased by setting binding bars. Compared to ordinary binding bars, the prestressed binding bars can decrease the longitudinal displacements corresponding to ultimate strength, but have little effect on the ultimate strength and displacement capacity after ultimate strength of the columns. The longitudinal displacements corresponding to ultimate strength of the columns decrease with the decreasing of space between binding bars. With the same section width and amount of binding bars, the bearing capacity of the columns improves with the increase of section long-broad-ratio, while displacement capacity after ultimate strength decreases with the increase of section long-broad-ratio. 相似文献
12.
In this study, nine simplified short composite columns consisting of core CFST (concrete filled steel tube) of different diameters and outer reinforced concrete were constructed to study their compressive performance under axial or eccentric compression. The failure mode is characterized by the crush of the outer concrete. The bearing capacity increases at first and then decreases with further increase of the position coefficient. It can be concluded that position coefficient is an important structural parameter that has considerable influences on the ultimate bearing capacity of the composite columns. The outer concrete, steel tubes and longitudinal reinforcement are found to work in a cooperative manner under axial or eccentric compression when the position coefficient is about 0.5. An improved bearing capacity algorithm that takes the position coefficient into account has been proposed based on the experimental and simulation results and current technical specification in China. It has been proven to be precise and safe. 相似文献
13.
Based on the test of high strength concrete (HSC)short columns confined with stirrups 8 under axial loads and 6 under small eccentric loads, the influence of stirrups confinement on stressstrain relationship and related parameter under monoaxial compression are studied, and the effect of the type of stirrups, stirrup ratio, etc. on the HSC columns ductility is analysed. Besides, the strength and deformation behavior of HCS columns under small eccentric compression are explored.Based on the experimental study, the complete stress-strain curves of confined HSC and the formula for calculating the related parameter are presented in this paper. 相似文献
14.
Based on the determined stress-strain relationship of steel and concrete after fire, a temperature field and mechanical model of bar-reinforced concrete-filled square steel tubular columns after fire was set up with using ABAQUS, and the model has been validated by testing results. Then this paper analyzed the side of section, bar ratio, fire duration time, steel ratio and material strength parameters on the bearing capacity of bar-reinforced concrete-filled square steel tubular columns after fire. It is found that fire duration time and side of section is the dominant factor. Lastly this paper puts forward a theoretical formula of bearing capacity of bar-reinforced concrete-filled square steel tubular columns after fire, for the post-disaster restoration and provides references for the reinforcement. 相似文献
15.
When the plastic hinge method is used to simulate the elasto-plastic properties of concrete-filled steel tubular structures,the plastic interactive yield surfaces of concrete-filled steel tubular column sections need to be defined.Although the fiber model approach can be well applied to the yield surface analysis,the numerical method is still complicated for the real applications.Therefore based on the experimental and theoretical researches on concrete-filled square steel tubular (CFST) members,this paper develops one method to determine the elastic element parameters.Then a simplified approach to quickly define the axial force-moment interactive plastic yield surface of concrete-filled square steel tubular columns is developed through theoretical analysis and a large number of parametric analyses.Finally,the fiber model method is adopted to verify the feasibility and validity of the proposed method.Results of the two methods are in good agreement,which indicates that the proposed method is reliable. 相似文献
16.
In order to investigate the fire-resistance performance of high-strength-steel column,this paper deduces the critical stress of high-strength-steel columns under the axial compression at high temperature by introducing the mechanical properties of high-strength-steel at high temperature.Moreover,coefficients of overall stability and critical temperature for high-strength-steel column under the axial compression are obtained which can provide a reference for design.The comparison of overall stability coefficient and critical temperature between high-strength-steel and normal steel is made.The results show that the overall stability coefficient and critical temperature for normal steel is not applicable for high-strength-steel,and the overall stability coefficient for high-strength-steel is smaller than that for normal steel.The paper uses the finite element analysis to validate the overall stability coefficient,and good match was found between them. 相似文献
17.
A 3-D finite element model is established by ABAQUS to simulate the behavior of the joints with concrete-filled steel tubular (CFST) column to steel beam using external stiffening ring.The load versus deformation curves of this type of joints are compared between theoretical and experimental results,and in good agreement.Parametric analysis is performed to study the flexural load-carrying capacity of the joint.The width of external stiffening ring,the steel ratio of CFST column,the ultimate strength of steel beam,the strength of steel tube and beam,the concrete strength,the axial load ratio,and the beam to column linear stiffness ratio are considered as parameters.The simplified practical design approach is proposed based on parameter analysis of the flexural load-carrying capacity of these joints.The practical calculated values are in good agreement with the FEM results. 相似文献
18.
Earthquake induced dynamic axial force in reinforced concrete (RC) bridge bent columns will not only change the yield strength of the columns but also change their stiffness, which is seldom considered by the common lumped plasticity line model. Based on the fiber element model results that taking into account the influence of dynamic axial force on strength and stiffness simultaneously, the axial force stiffness interaction effect on the seismic responses of RC double column bridges was analyzed. The results show that, axial force stiffness interaction has a large effect on the seismic responses of the double column bridge in the elastic range, and it does not alter the ultimate capacity of the columns. Since the stiffness of the columns under compression and tension dynamic axial forces offset each other, the global displacement of bridge bent with equal columns is relatively unaffected by the axial force stiffness interaction, however, the differences of the column member forces are manifest. For the short column controls the global stiffness, the axial force stiffness interaction has significant influences on both the global displacement and member force responses. The influences become larger as the irregularity of the bridge bent increases, so the interaction between axial force and member stiffness should be sufficiently considered in seismic analyses. 相似文献
19.
配置600 MPa级高强钢筋T形柱抗震性能试验研究 总被引：2，自引：0，他引：2
600 MPa级钢筋是一种新型高强度钢筋,为研究该钢筋应用于异形柱结构体系的可行性,对7根不同轴压比、体积配箍率和钢筋强度的混凝土T形柱试件进行低周往复荷载试验,分别对其承载力、位移、滞回曲线、骨架曲线、刚度退化和耗能性能进行研究,综合评估其抗震性能。研究结果表明：配置600 MPa级钢筋的混凝土T形柱具有良好的变形能力和承载能力,提高配箍率能有效提高试件的抗震性能,提高轴压比可以提高试件的承载力,但降低其变形能力。随着钢筋强度的提高,试件的承载力显著提高。 相似文献