葫芦口金沙江大桥的吊装施工与抗风措施

介绍了葫芦口金沙江大桥的缆索吊装施工工艺和合龙过程,另外还介绍了施工中采取的抗风措施(该桥处于季风强劲区域),可为在类似条件下建设大跨度拱桥借鉴.     

基于结构动力学特性的高桩码头横向排架传感器优化布置方法

为了对高桩码头结构健康监测系统中的传感器布置提供理论指导,提出了一种基于结构动力学特性的传感器优化布置方法。在对高桩码头代表性结构单元横向排架进行结构动力学分析的基础上,运用模态应变能法选择高桩码头横向排架传感器初始测点;建立初始模态矩阵,然后利用模态置信度法和序列法对模态矩阵进行迭代、优化,确定传感器测点布置。建立了单个横向排架的数值仿真模型,利用传感器优化布置方法得到横向排架7根桩基的传感器测点布置结果,并对测点布置进行评估。模态向量间的夹角趋于正交,传感器布置方案有效,证明该传感器优化布置方法适用于高桩码头的传感器优化布置。     

基于离散天牛群算法的高桩码头传感器优化布置

天牛须搜索(BAS)及其优化算法天牛群(BSO)算法是近两年新兴的一种生物启发式算法,具有易实现、收敛速度快等特点,但其仅适用于连续函数优化问题。目前高桩码头结构健康监测系统中传感器优化布置研究较少、布置方法存在盲目性。针对高桩码头传感器优化布置这一具体的离散问题,采用"0-1"编码的方法,引入位置变换概率的思想和离散化天牛群算法,基于模态置信度准则,提出了一种基于离散天牛群(BBSO)算法的高桩码头传感器优化布置方法。以某高桩码头为例,研究了该方法的应用,并与传统的离散粒子群(BPSO)算法进行了比较。结果表明,该方法比传统的BPSO算法更适合和有效。     

浅埋长阳极地床接地电阻的测试误差分析

电流极引起的电场畸变和电位极位置与远方大地位置的差异,是三极直线布线法测量长阳极地床接地电阻的主要误差来源。在采用网孔分析法对测量原理进行分析的基础上,结合现场测试结果发现：随着电流极与阳极地床距离的增加,接地电阻测试曲线上开始出现平缓区;接地电阻测量值逐渐接近计算值,测试误差减小。在现场场地限制的条件下,缩短电流极与阳极地床的距离进行多组测试后,进行拟合分析也能够满足工程需要。     

模块化6 - SPS SteWart机床位置参数识别

描述了模块化Stewart机床的基座关节位姿识别的一种方法，即通过测量动平台的位置，基座 关节位姿的变化及可伸缩连杆长度增量产生一套识别参数的非线性方程。对于Stewart机床的实际应 用具有重要的指导意义。     

大跨径钢桁架拱桥健康监测系统传感器优化布置研究

以九江长江大桥主跨钢桁架拱桥为工程背景,以其有限元模型分析结果为基础,基于扩展有效独立法理论进行传感器优化布置,最终形成该桥的健康监测系统传感器测点布置。     

基于EfI法的桥梁模态测试中传感器优化布置

为确定大跨刚性桁架柔性拱桥传感器的最优布置位置,采用ANSYS软件建立全桥有限元模型,分析其动力性能,以模态向量矩阵和有效独立法为准则,在MATLAB环境下开发了三维加速度传感器优化布置工具箱,用于刚性桁架柔性拱桥的传感器优化布置,同时,对桥梁结构模型进行模态试验验证传感器布置方案的合理性.研究结果表明,所选传感器位置能够较好地拟合出桥梁振型,基于EfI的传感器优化布置工具箱对大跨刚性桁架柔性拱桥传感器布置是行之有效的.     

桥梁结构模态测试中传感器优化布置的序列法及应用

介绍桥梁结构模态测试中传感器优化布置的序列法,该法以模态置信度MAC矩阵的最大非对角元为目标函数,采用逐步累积或逐步消去的方法对传感器进行优化布置,直到传感器数目最理想、位置最优。最后举例说明了该法在桥梁结构模态测试中的应用。     

Automated manufacture of optimised shape-adaptive composite hydrofoils with curvilinear fibre paths for improved bend-twist performance

Composite marine propellers improve hydrodynamic efficiency by inducing bend-twist coupling and allowing for passive pitch changes. One critical limitation, however, is the extent to which a composite propeller blade can deform and cause a pitch change without incurring structural failure. Recent numerical studies showed that curvilinear tows could improve the structural response of a composite blade by lowering its deflection or stress and strain required to induce a pitch change, but no experimental validation has been carried out before. The current study, thus, presents the manufacture of composite sandwich hydrofoils made with steered tows using automated fibre placement and validates the curvilinear tow benefits. Two hydrofoils were optimised with straight and curved fibre path layups, respectively and were manufactured for mechanical testing. The manufacturing complications arising from steering curvilinear tows in a three-dimensional convex mould are also discussed in the paper. The study found that significant tow buckling occurred near the tool cavity edge due to excessive steering radius during manufacture. The follow-up structural cantilevered tests showed that the experimental results were consistent with the FE predictions despite the presence of some manufacturing defects. The experiment agreed that the hydrofoil manufactured with curved tows achieved a similar tip twist but a significant reduction in deflection and critical principal strains compared to the hydrofoil made with straight tows. The use of a foam core reduced the overall weight of the sandwich hydrofoils by about 25% compared to that of a fully-carbon composite hydrofoil, and the numerical analysis showed that the core shear failure induced by transverse shear stresses was unlikely to occur.