基坑支护上的水土压力共同作用问题及建议

基坑支护结构上实测的内力常常远比用经典土力学理论计算的数值小。在计算方法和水土相互作用机理方面对于水土“分算”和“合算”这一有争论的问题进行了分析和讨论,该文探讨了土的微观结构特征及其对工程特性的影响,基于微观层面分析了土中水的存在类型及特征,研究了水土共同作用韵微观机理,给出了粘性土能否传递孔隙水压力的判别公式,指出这是一个有待于深入研究和探讨的课题。     

长联无缝桥梁成套技术在广西那角中桥的应用

修建全无缝桥梁可以彻底解决桥梁伸缩装置问题。那角中桥是广西第一座应用长联无缝桥梁成套技术的半整体式全无缝桥梁。文章通过介绍那角中桥设计与运营情况,分析了长联无缝桥梁成套技术应用所带来的经济与社会效益,为该技术的推广应用提供依据。     

Joint distortion model for progressive image transmission using error correcting arithmetic codes

A novel joint source channel distortion model was proposed, which can essentially estimate the average distortion in progressive image transmission. To improve the precision of the model, the redundancy generated by a forbidden symbol in the arithmetic codes is used to distinguish the quantization distortion and the channel distortion, all the coefficients from the first error one to the end of the sequence are set to be a value within the variance range of the coefficients instead of zero, then the error propagation coming from the entropy coding can be essentially estimated, which is disregarded in the most conventional joint source channel coding （JSCC） systems. The precision of the model in terms of average peak-signal-to-noise has been improved about 0.5 dB compared to classical works. An efficient unequal error protection system based on the model is developed, and can be used in the wireless communication systems.     

兴宁市兴旺大桥主桥总体设计

兴旺大桥为(29.25m+76.5m+29.25m)中承式系杆拱桥,拱肋外倾24°,边腿与主拱脚形成V撑。为减小温度效应对拱梁固结处及基础的不利影响,在主跨设2道伸缩缝,同时设置系杆以平衡拱的水平推力。通过兴旺大桥主桥的总体设计介绍,为同等跨径的特色景观桥梁设计提供一种选型参考。     

钢-混凝土混合结构在大跨度连续刚构桥中的应用

重庆石板坡公路长江大桥采用填充混凝土后板式钢—混凝土接头。在轴力、弯矩和剪力的作用下,钢—混凝土接头处将产生轴向压应力、拉应力和剪应力。压应力由承压板及PBL剪力键共同传递,拉应力、剪应力主要由PBL剪力键传递。计算得到钢—混凝土接头的最不利荷载组合内力。在钢—混凝土接头附近截取18m长的1个梁段,将混凝土与贯穿钢筋进行耦合、贯穿钢筋与PBL板进行耦合,采用实体单元、板单元和梁单元,建立钢—混凝土接头有限元模型,利用有限元软件ANSYS进行仿真分析,得到钢—混凝土接头各部分的应力分布。结果表明:结构各构件在设计荷载下并未出现超出材料强度的应力峰值;剪力主要靠腹板上的PBL剪力键传递;有效的预应力体系是钢—混凝土接头可靠性的根本保证。     

公路桥头及桥梁伸缩缝跳车的产生与防治

论述公路桥头及桥梁伸缩缝跳车的危害及产生的原因,提出防治措施。     

Dynamic analysis of a pantograph-catenary system using absolute nodal coordinates

The dynamic interaction between the catenary and the pantographs of high-speed trains is a very important factor that affects the stable electric power supply. In order to design a reliable current collection system, a multibody simulation model can provide an efficient and economical method to analyze the dynamic behavior of the catenary and pantograph. In this article, a dynamic analysis method for a pantograph-catenary system for a high-speed train is presented, employing absolute nodal coordinates and rigid body reference coordinates. The highly flexible catenary is modeled using a nonlinear continuous beam element, which is based on an absolute nodal coordinate formulation. The pantograph is modeled as a rigid multibody system. The analysis results are compared with experimental data obtained from a running high-speed train. In addition, using a derived system equation of motion, the calculation method for the dynamic stress in the catenary conductor is presented. This study may have significance in providing an example that a structural and multibody dynamics model can be unified into one numerical system.     

山东体育学院教授公寓楼(Ⅰ期)结构设计

介绍山东体育学院教授公寓楼结构设计中所选用的参数,包括适用高度、高宽比、结构平面布置、防震缝和沉降缝、基础埋深等指标,正确理解相关规范并采取相应的结构设计,使结构安全适用、经济合理。     

加强实践教学,培养具有国际竞争力的航运人才

我国加入WTO和STCW78/95公约实施后,如何拓宽实践教学思路,培养出符合STCW78/95公约、适应国际航运人才市场需求,具有较强实践能力和竞争能力的航运人才,是航海类专业实践教学改革的需要研究的重要课题。