混凝土箱梁桥面板计算与试验分析

混凝土箱梁板面板计算,一般采用近似计算,通过混凝土箱梁板面板实测值与几种近似法计算值的对比分析,建议设计中采用美国学者Westergard法计算桥面板的内力。该法也是美国桥梁设计规范计算桥面板的理论基础。     

In vitro prediction of canine urolith mineral composition using computed tomographic mean beam attenuation measurements

Determination of urolith mineral composition is critical for management of urolithiasis in dogs and cats. Using computed tomography, urolith physical density, and hence chemical composition, can be quantified using mean beam attenuation measurements (Hounsfield units; HU). This study was designed to establish in vitro reference ranges for three types of compositionally pure uroliths retrieved from dogs. Sixty-six canine uroliths (22 uric acid, 21 calcium oxalate, 14 struvite, nine mixed or compound) were placed in a phantom array. Uroliths were scanned at 120 kVp, 200 mA, and 80 kVp, 200 mA. The region of interest (ROI) for mean HU calculation was determined using two techniques, and reference ranges were calculated for each kVp using either ROI technique. HU for urolith types of pure composition were statistically different (Wilcoxon's two-sample test, P < 0.0083 [Bonferonni correction with six comparisons for total P < 0.05]) using both ROI techniques at either kVp. Struvite uroliths were not statistically different from mixed or compound uroliths. The accuracy for determination of composition of pure uroliths ranged from 86% to 93%; the prediction accuracy for each urolith mineral type and for all uroliths in general was highest when the ROI was hand-drawn just within the visible urolith border at 80 kVp. Technique of ROI determination and kVp that yielded the highest sensitivity, specificity, and positive and negative predictive values varied for each urolith type. Therefore, in this study, HU could be used to differentiate three types of uroliths of pure mineral composition in vitro. Further studies are needed to determine the predictive value of HU in vivo.     

型钢混凝土结构施工安全研究

针对对型钢混凝土柱与梁的施工,本研究结合实际工程中的问题对其施工质量和施工安全进行了说明,并对安全保证措施、安全措施的执行进行了探讨.重点对于型钢混凝土结构的混凝土浇筑工作以及浇筑质量、施工安全进行了讨论     

无粘结预应力筋极限应力研究

对竖向和水平荷载试验中１９榀ＵＰＣ框架梁中的ＵＰＳ的应力变化与极限应力进行探讨，并结合预应力混凝土结构非线性分析模型，定性定量分析了结构中ＵＰＳ极限应力的主要影响因素，如荷载形式、配箍率、综合配筋力比和跨高比，并提出ＵＰＳ极限应力计算的修正公式，更适合于ＵＰＣ框架在地震设防区的使用。     

碳纤维加固混凝土梁挠度的理论分析

本文对碳纤维布加固钢筋混凝土梁的挠度进行了研究,针对钢筋是否屈服的不同情况,分别讨论碳纤维布加固后梁的挠度计算公式。     

开口薄壁杆的非线性动力稳定性分析

基于弹性薄壁杆的经典理论考虑到拉压，弯曲及扭转的耦合效应，建立了开口薄壁杆的非线性运动控制方程组，应用谐波平衡法。     

弯曲应力实验小梁保护装置的设计研究

本文通过对弯曲应力实验小梁的失效分析 ,研究了如何让实验小梁在允许的范围内尽可能进行多的实验次数的保护措施。这对于实验室的建设 ,节约实验经费开支 ,具有现实意义     

变截面钢板弹簧的曲梁模型

通过建立钢板弹簧的曲梁模型，应用虚力原理求解位移，得到了变截面钢板弹簧刚度的几何非线性特性。     

松原龙华松花江特大桥箱梁结构弹性模量测试

利用共轭梁（虚梁）法在施工监控过程中对箱梁结构的弹性模量进行测试,测试的数据进行分析,得出结果,该结果可为施工提供参考.     

简支梁在动载荷作用下竖向动挠度的计算理论研究

本文对简支梁在匀速常量力和匀速脉冲力的作用下，应用结构动力学理论，对梁的动力响应给出了近似解答。