预应力高强混凝土—钢纤维高强混凝土连续梁的试验及非线性分析

完成了四片高强混凝土－钢纤维高强混凝土变截面预应力连续梁的静载试验，记录了四片的梁的弯矩－挠度曲线及弯矩重分布过程，指出了弯矩重分布是与裂缝的出现和发展密切相关的，讨论了部分预应力比PPR对连续梁内力重分布的影响，最后对四片试验梁进行了材料非线性分析。     

拱式结构几何非线性分析的样条有限点法

提出了用样条有限点法(SFPM)分析拱式结构几何非线性问题。以位移u和w作为基本未知量,采用3次B样条函数作为位移函数,从最小势能原理出发,建立了样条离散化的非线性刚度方程,推导了非线性刚度矩阵的精确显式。     

三维夹层映射无限元

提出三维10结点映射夹层无限元模型及相应模式。在半无限区域的岩土工程中,用此单元与夹层有限单元耦合系统模拟无限区域的软弱夹层,与常规的有限元法相比,取较小的计算范围,就能得到较高的计算精度。采用此模型,将节省大量的数据准备工作量和机时,具有显著的经济性。此模型还具有概念清晰,编制程序简单,易于在微机上实现的特点。通过赋存软弱夹层的半无限地基在法向荷载作用下的算例分析,表明此模型具有的优越性。     

曲箱梁考虑剪力滞效应的弯扭耦合分析

本文以薄壁曲梁理论为基础，建立了薄壁曲线箱形梁考虑剪力滞效应的控制微分方程，提出了用样条有限点法（SFPM）分析薄壁曲线箱形梁剪力滞问题，考虑曲线箱梁的弯曲，扭转，翘曲和剪力滞效应等，以位移v,w和θ作为基本未知量，采用三次B样条函数作为位称插值函数，从最小势能原理出发，建立了样条离散化的刚度方程，推出了精确的刚度矩阵显式，并编制了相应的计算程序。样条有限点法将三维箱梁弯曲问题简化为一维问题，由于样条函数具有很好的光滑性，因而此方法能以极少的未知量得到较高的精度，文中给出了典型的计算实例，还分析了曲率半径及荷载形式对剪力滞效应的影响。     

Risk-identification-based hybrid method for estimating the system reliability of existing jacket platforms under fire

This paper proposes a risk-identification-based hybrid method for estimating the system reliability of steel jacket structures under fire.The proposed method starts with risk identification;according to the results of hazard identification and Dow’s fire and explosion index(F&EI) methodology,the most dangerous hazard sources are determined.In term of each equipment layout in steel jacket structures,fire load is imposed and elasto-plastic analysis is performed.According to the deformed state of steel jacket structures,the weakest failure mode of steel jacket structures is identified.In order to know the effect on ultimate bearing capacity of the offshore structural system,a series of elasto-plastic analyses are performed in which single failure element contained in the weakest failure mode is removed from the whole offshore platform structural system.Finally,the failure function of the steel jacket structure is generated and the failure probability of the steel jacket structure system is estimated under fire by genetic algorithm via MATLAB program.     

预应力高强混凝土连续梁的变形及承载能力研究

首先，以PPR为变量，设计了四片两跨预应力高强混凝土变高度T形截面连续梁，完成了四片梁的静载试验，成功地记录了试验梁从初始荷载至弯曲破坏的荷截－变形曲线。其次，在试验的耻，提出了用刚度折减的方法计算预应力高强混凝土连续梁开裂后的变形，计算值与试验值相比，能得到较为满意的结果。最后，以试验梁的承载能力的研究内容，采用塑性分析，线弹性分析，改进的弹性分析（考虑弯矩重分布）以及非线性有限元分析方法计算试验梁的破坏荷载，并与试验结果相比较，探讨合理的安全储备系统，同时建议现行铁路桥涵规范在设计高强混凝土连续梁时，考虑弯矩重分布影响。     

Nonlinear free vibration analysis of thin-walled curved beam with non-symmetric open cross section

A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section. The kinetic and potential energies were derived by the virtual principle. The energy function includes the effect of fiexural-torsional coupling, the torsion warping and the shear centre location. For finite element analysis, cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements. Each node possesses seven degrees freedom including the warping degree of freedom. The nonlinear eigenvalue problem was solved by the direct iteration technique. The results are compared with those for straight beams as available in the literature. The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented.