混凝土的断裂特性对工程安全起着关键作用.相场断裂法能方便地模拟出裂纹的动态扩展过程,利用UEL和UMAT子程序,实现混凝土相场断裂的Abaqus二次开发,分析了单元尺寸和长度尺度参数对三点弯曲混凝土梁裂纹扩展宽度的影响.研究结果表明:当单元尺寸足够小时,裂纹宽度将不再受单元尺寸的影响,裂纹宽度随长度尺度参数减小而减小.

为研究车轮横向分布对钢桥面板顶板-U肋连接处疲劳损伤的影响,以佛山平胜大桥为研究对象,通过数值模拟,计算各车型车轮荷载不同横向位置下顶板-U肋连接处的应力,采用英国规范BS5400计算该处的疲劳损伤度;建立车轮分布模型,计算车轮在车道不同位置的分布概率,提出考虑车轮横向分布的疲劳损伤计算方法.结果表明,顶板-U肋连接处的应力幅受车轮横向分布的影响范围较小,约为1.5 m,不必考虑多车效应;U肋损伤分布差异较大,U肋底板损伤比腹板损伤更严重;考虑车轮横向分布效应后,顶板-U肋连接处的疲劳寿命计算值提高69％,钢桥面板疲劳损伤分析中应考虑车轮的横向分布效应.

依据已有支管受轴向荷载的T型焊接圆管节点的实验数据,使用ANSYS进行了有限元分析,并利用临界距离理论的点法和线法,预测了构件的疲劳强度.选取第一主应力点沿其最大梯度方向作为临界距离理论的聚焦路径.研究结果表明:预测的疲劳强度与疲劳强度实测值的误差在20％以内.临界距离理论能够在实验数据不足的情况下对焊接管节点的疲劳性能提供较精确的理论预测,为工程应用提供有价值的参考.

In order to set up an InSAR-based bridge safety early-warning system,the de-formation pattern of bridge under the random load must be considered.After setting the arti-ficial PS points in the BDKP(Bridge Deformation of Key Points),the deformation pattern of the BDKP under the random system temperature and the random traffic flow is analyzed u-sing finite element method.The results show that the whole deformation characteristics of the bridge can be characterized by the deformation of the BDKP.Daily temperature can be divided into four periods,and the random deformation pattern of bridge in different periods was analyzed.The influence of temperature of the random system can be eliminated from InSAR data.The random system temperature has a significant influence on the deformation of the BDKP,even up to cm magnitude.The influence of random traffic flow on the de-formation of the BDKP is much less than that of the random system temperature,in which the deformationof the BDKP is in mm magnitude.

随着信息技术的不断发展，多媒体教学形式以其良好的直观性、趣味性和交互性为越来越多的人所接受。提高多媒体教学水平，既要有高质量的多媒体课件系统，又必须以教师为本，加强多媒体课件与课堂教学的有机整合。多媒体教学效果与课件本身质量有很大的关系，需要教师根据每堂课自己的体会、同行之间的交流、学生的反馈情况，对媒体课件进行不断的更新完善。一个好的多媒体软件系统，只有与教学经验较丰富的教师有机结合，才能真正发挥多媒体教学优势。

Using numerical simulation finite-element method,the vertical supporting capacity of large diameter predrilled cast-in-place pile is calculated.The influences of different thickness of bottom settlings are analyzed under pile and mud cakes around pile on the ultimate supporting capacity of single pile.The importance of controlling the thickness of bottom settlings and mud cake is discussed.Some particular measures were put forward as well.

建立了双参数弹性地基上的正交异性矩形薄板自由振动位移函数微分方程,并得到其一般解.这可用以精确地求解板在任意边界条件下的自由振动问题.以四边固定的正方形板为例进行了分析,计算过程简单,便于实际应用.亦适用于求解单参数弹性地基和各向同性板情形.

A general solution to differential equation for deflection function in bending problem of orthotropic rectangular thin plate on elastic foundation is established.It can be used to solve the bending problem under arbitrary load and arbitrary boundaries. A square plate with four edges free and a concentrated load acted at the center is calculated. This general analytical method gives an exact solution.The theoretical analysis is simple and the calculation process is easy and available in practical engineering.

材料力学是一门在工程中应用广泛的学科.然而,多年来材料力学的教学内容相对静止,与日新月异迅猛发展的现代工程技术越来越不相适应;教学方法与考核方式不利于激发学生的创新意识,与面向21世纪、培养创造性人才的要求不相适应.针对上述弊端,我们自1995年开始,在对国内外材料力学教学历史与现状进行广泛深入调研的基础上,从教学内容、教学模式、考核方法等多方面对材料力学教学进行了较为系统的改革,形成了比较完整的材料力学教学新体系,提高了教学水平与质量,激发了学生的创新意识,促进了中青年教师的成长.