下梁

Several parameters for the fire resistance on cross section of a reinforced concrete T-beam exposed to the ISO834 standard fire are analyzed,including the fire time and the ration of load.

结合国内外建筑结构火灾试验，引入开裂准测和非线性本构关系，提出了火灾下结构有限元分析思路，利用数值模拟程序分析了火灾高温下钢筋混凝土T梁截面的温度分布，研究了火灾时间、荷载比对ISO834标准火灾升温过程下钢筋混凝土T梁桥挠度的时变效应规律及开裂状况。

In order to acquire the spatial stress distribution of the pier-beam fixed joint , a pier-beam fixed joint finite element space model is established and analyzed in different loading cases.

为掌握石板坡大桥墩梁固结点的三维应力状态，建立了墩梁固结点结构分析的空间有限元模型，根据施工过程中及成桥后的工况，分别进行了空间有限元计算，得到了墩梁固结点在三种工况下的应力分布情况，检验了设计的安全性与合理性，提出了改善墩梁固结点应力的措施和方法，为设计和施工提供了科学的依据。

Concretely, firstly with Timoshenko beams, the fundamental formulae of solutions of dynamical equations, boundary conditions and initial conditions have been transformed by Laplace transformation. Secondly, in the Laplace regions , we gain the analytical solutions of impact forces at the impact contact points, shear and maximum inverse stress of beams. Then, by using Durbin numerical inverse method, we gain the numerical solutions of Timoshenko beams under various restriction conditions. Moreover, the graphs about impact forces at the impact contact points, shear and maximum inverse stress of beams can be obtained too.

把Timoshenko梁力学模型动力学方程的基本解形式、边界条件以及初始条件进行Laplace变换，在Laplace区域得到了冲击接触处的冲击力、整个梁的最大弯曲应力和剪力的解析解，然后利用Durbin数值反演的方法得到了各种约束条件下的Timoshenko梁模型时间-空间的数值解，得到了冲击接触处的冲击力、梁各处的最大弯曲应力和剪力的曲线图。

Second, on the basis of classical girder theory, girder element stiffness matrix considering shearing deformation is deduced, the method of calculation of value of shearing deformation is illustrated, and how far effect on inner force and deformation considering sheering deformation is discussed. Through comparison inner force and deformation between considerations in shearing deformation and not, several results are achieved and several suggestions to calculation are pointed out.Third, prestressed reinforcement is considered in the paper.

其次，在经典梁理论的基础上，本文推导出考虑剪切变形的平面梁和空间梁单元刚度矩阵，阐述了剪切变形系数的计算方法，讨论了在不同箱梁截面高度情况下，剪切变形对结构内力值和变形值的影响，并与不考虑剪切变形影响的结果作比较，得出有关结论，并对工程设计计算做出了一些建议。

In the first place, the normal flexible body dynamics modelling method of continous system is built based on hamilton principle. And then taking the flexible beam tunning in the horizontal plan for example, in the assumption of Euler-Bernoulli beam,the identical linearilized vibration differential equation is deduced according to geometry constraint conditions .

首先基于Hamilton原理建立起一般柔性体连续系统的动力学建模方法，进而以水平面内作大范围回转运动的柔性梁为例，在Eu1er-Bemoulli梁模型的假设前提下，根据轴向不可伸长的柔性梁的几何约束条件，推导出作大范围刚体运动的柔性梁连续系统的一致线性化振动微分方程。

According to the structure characteristics of L-B composite brake beam, the finite element model of L-B brake beam based on contact is established, and the stress distribution of the brake beam in different conditions calculated is using I-DEAS software. Calculated results show that the stress concentration mainly generates in the root of brake header slider, which fit with the faults in actual operation, and provide reliable basis to improve design and optimization.

根据L-B型组合式制动梁的结构特点，运用I-DEAS软件建立基于接触的L-B型制动梁有限元模型，并计算了制动梁在不同工况下的应力分布，计算结果表明应力集中主要发生在闸瓦托滑块根部，这与实际运行中出现的故障较为吻合，为制动梁的改进设计和结构优化提供了依据。

In order to improve the life of cement concrete bridge deck pavement,compound beam test was used to research the fatigue characteristics of hot mixed asphalt courses on bridge deck,finite element analysis method was employed to make the mechanical response of compound beam accord with that of actual bridge deck under the same load,the fatigue test was done for compound beams with different pavement structures.

为了提高水泥混凝土桥面沥青混凝土铺装的使用寿命，以复合梁试验评价不同的桥面沥青铺装结构的疲劳性能，采用有限元法分析荷载作用下复合梁试件具有与实际梁体一致的应力响应，并采用复合梁疲劳试验测试不同桥面沥青铺装层组合的疲劳寿命。

Then, safety analysis method was constituted considered the typical damage of concrete beam bridge. 5. By amending the reduction rate of loading capacity used in Code for Maintenance of Highway Bridges and Culvers (JTG H11-2004), a new reliable index is presented in the same safety standard to reflect the relation between load and resistance. According to the basic principal of calibration method, the recommended gradation index was computed under various factors such as different load combinations, vehicle operating status and different failure modes. With these calculated numerical values, the calculated reliability indexes standard for the estimation of safety degree of in-service concrete girder bridge members was ultimately obtained.6. Based on the related standards and results on crack and displacement that cannot continue to loading at home and abroad, the evaluation grade of the concrete beam bridge is proposed by analogy.

针对材料和构件损伤对混凝土梁式桥抗力的影响，基于材料和构件层次典型损伤的修正计算公式，在结构既有以及时变抗力评估的概率模型基础上，通过误差传递公式获得抗力统计参数，对抗力进行修正，构成了考虑混凝土梁式桥典型损伤的安全性分析方法。5、依据校准法原理，将《公路桥涵养护规范》(JTG H11-2004)中不同类别承载力下降率转化为修改分项系数，分别计算了轴心受压、轴心受拉、受弯、大偏心受压、受剪构件在各种情况下的可靠指标，根据破坏类型对校准结果进行分析，提出了基于可靠度的公路混凝土梁式桥安全性评定等级。6、基于不能继续承载的裂缝和位移的相关国内外规范和研究成果分析，通过类比提出了混凝土梁式桥不能继续承载的裂缝和位移评定等级界限。

The flexural capacity, deformation and failure modes of beams with different parameters can be analyzed using the program, such as types of plan and prestressed tendons(extrenal prestessed tendons, internal unbonded prestressed tendons, internal bonded prestressed tendons), jacking and effective stress in external prestressed tendons, configuration of the deviators, properties of tendon, ratio of span to effective depth of the beam and load pattern, initial loading state at tendon jacking, etc.(3) Nonlinear behaviors of the concrete beam prestressed with external or internal unbonded tendons were studied by the program developed.

本程序可以对任意截面型式的预应力(体外预应力筋、体内无粘结预应力筋、体内有粘结预应力筋)混凝土梁和普通钢筋混凝土梁进行非线性全过程数值分析计算，程序可以就转向块的布置方式、体外预应力筋纵断面形状、体外筋有效预应力的大小及材性、张拉预应力筋时梁的持荷状态等因素对体外预应力混凝土梁在外荷载作用下的强度、变形特征、破坏模式等的影响进行分析研究。

The thrust coefficients and propulsive efficiency of a two-dimensional flexible fin with heaving and pitching motion were computed using FLUENT. The effect of different locations of the pitching axis on propulsive performance was examined using three deflexion modes which are respectively, modified Bose mode, cantilever beam with uniformly distributed load and cantilever beam with non-uniformly distributed load.

利用FLUENT软件数值计算了二维柔性鳍作升沉纵摇运动时的推力系数及推进效率，探讨了修正Bose变形方程、均匀载荷和非均匀载荷悬臂梁变形方程等三种柔性模式下纵摇轴位置对摆动鳍推进性能的影响，其中纵摇轴在尾缘处能够获得更大的推力，而最高的推进效率分别对应修正Bose模式下纵摇轴距首缘1/3弦长处和悬臂梁柔性变形模型下纵摇轴距首缘2/3弦长处。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。