虎门大桥主体工程测量放样方法与精度分析

本文根据虎门大桥六大件主体工程的实际位置情况，推导了极坐标法施工放样的精度估算公式，并用该公式估算了六大件主体工程施工放样的精度，认为极坐标法适用于六大件主体工程的施工放样。文中所介绍之方法，对其他大型桥梁施工控制，有一定推广和参考价值。     

SAP2000软件对桥梁结构的MPA分析

基于SAP2000软件的标准Pushover分析功能,进行适当改进,通过多次运算,在SAP2000软件上完成了MPA分析,并用该方法计算一座实际桥梁结构的非线性反应,与标准Pushover分析的结果进行比较,表明SAP2000对高阶振型起主要作用的结构也能得到较准确的计算结果。     

Multi-scale modeling of fatigue crack propagation applied to random sequence of clustered loading

Fatigue crack propagation in marine structures is obviously governed by mechanics of the considerably different four levels of multi-scale problems. Problems of structural response to environmental loads have length scale of several hundred meters, whereas possible detectable size of cracks from initial defects in a weld is of the order of millimeters. Once a fatigue crack initiates, crack tip plasticity is of the order of several grain sizes, while the resulting fatigue crack growth in each load cycle is of the order of nanometers. In our previous work, the first author and their associates have developed the so-called CP-System, which can treat the first two multi-level problems as an integrated system. Furthermore, we have incorporated the third level of mechanics by using the stress intensity range corresponding to the repeated tensile plastic deformation ahead of the crack tip. In the present paper, we shall discuss a more rational integral equation-based formulation in order to integrate the third and fourth levels of micro-mechanics to the first two levels of continuum mechanics.The method is then applied to fatigue crack propagation under the effects of random sequence of clustered loading. As an example of the random sequence of clustered load, we shall use the so-called “storm model”. In the crack propagation simulation, we have to take into account of the plastic wake on the crack surfaces, whose thicknesses are influenced by the material parameters involved in the crack growth model. These parameters are first identified by the fatigue tests under combined constant and random loading using a CT specimen. Then, fatigue crack growth is investigated by numerical simulation and fatigue tests for various random sequences of clustered loading. The experimental and numerical results agree quite well with each other, and fatigue crack propagation is found to be considerably retarded under random sequence loading, so that the conventional equivalent stress approach may provide rather conservative results to the real seaway loading.     

索结构六节点等参元非线性有限元法

针对索结构几何非线性的特点,提出了一种六节点等参数单元有限元模型,采用5次多项式作为位移插值函数及单元初始形状函数,假定索是理想柔性,且满足胡克定律,基于修正的Lagrangian坐标描述法,建立了非线性有限元基本方程和切线刚度矩阵,利用Newton-Raphson法进行求解.     

港口水工建筑物施工期通航安全保障研究

港口水工建筑物处于施工期间,由于施工自身的施工特点,对施工水域及其附近通航水域中正常航行的船舶构成一定的影响.通过分析施工期对通航环境的影响及施工水域通航安全管理实际,提出保障施工水域通航安全的主要措施与建议.     

港珠澳大桥主体混凝土结构耐久性实时监测设计

根据影响港珠澳大桥主体混凝土结构耐久性关键因素,从传感器的选型、监测点的布置、传感器的安装等方面给出了港珠澳大桥耐久性实时监测的设计方案,为类似工程的耐久性实时监测提供参考。     

桥梁施工临时结构中容许应力设计方法

桥梁施工过程中需要投入临时结构,对这些临时结构而言,投资过大容易造成浪费,但如果投资过小或不重视则极易引起重大安全事故。从临时结构的定义、特点以及存在问题入手,探讨采用容许应力法设计临时结构需解决的问题,为桥梁施工临时结构的设计提供依据。     

一种新型浮式单体结构设计及波浪稳定性试验研究

研究制作了一种抗风浪能力强,移动、拼接灵活、多用途、稳定性较好的新型超大型浮体码头模型。根据相关理论资料确定浮体码头的形状和尺寸,为验证其破浪稳定性,进行了初步模型试验研究。通过模型试验,得到了新型浮式单体结构相对危险的工况。实验结果表明：该种新型浮式单体结构的波浪稳定性要比传统的箱型结构好。     

Computational method for prestress developing of tensile cable-net structures

The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation is normally coupled with the kinematic mechanism movement. Firstly, the basic equations of prestress developing by moving boundary joint are derived from the total potential energy equation. Secondly, the presumed initial tension is proposed to impose into the elements and avoid the singularity of global stiffness matrix. And the self-stress mode which is calculated from the equilibrium matrix with singular value decomposition is employed as basically presumed initial tension. By applying boundary movement increment, an iterative computation is developed to calculate the updating geometric configuration and tension evolution. Finally, the MATLAB program is coded from the presented method, and numerical examples indicate that this computational method is effective and has theoretical significance and valuable guide to design and construction of tensile cable-net structure.