The second order characteristic condition for plastic flow     

Graham Weir  Roger Young 《国际地质力学数值与分析法杂志》2003,27(15):1299-1316

In this paper the second order characteristic (discontinuous bifurcation) condition is derived for the granular flow (fully plastic) equations. This second order bifurcation equation is shown to be formally identical to the first order localization requirement during steady elastoplastic deformation provided the elastic compliance tensor is substituted for the product of the plastic multiplier with the flow Hessian. For isotropic yield and flow functions the invariant form of the characteristic condition is given in detail, as well as an alternative expression in adapted co‐ordinates. The characteristic condition can be regarded as defining a hardening function which is maximized to identify the critical angles. When the method is applied to 3D Coulomb flow, Mohr's 3D fracture plane conditions are obtained uniquely. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Feasibility of pre-earthquake strengthening of buildings based on cost-benefit and life-cycle cost analysis, with the aid of fragility curves   总被引：1，自引：1，他引：0  

Andreas J. Kappos  E. G. Dimitrakopoulos 《Natural Hazards》2008,45(1):33-54

There are two fundamental questions this article aims to deal with. First, whether a pre-earthquake strengthening of a large and heterogeneous building stock (the emphasis here is on building types common in S. Europe), is economically feasible or not, and second what is the optimal retrofit level for mitigating the seismic risk. To this purpose contemporary decision making tools, namely cost-benefit and life-cycle cost analyses, are tailored to the needs of the present study, and implemented with the aid of an ad-hoc developed new software application (COBE06). A method for estimating the reduction in structural vulnerability due to retrofit is proposed, as well as a methodology to determine the optimum retrofit level using the fragility curve approach. Finally, the proposed methodology is used in a pilot application that concerns the city of Thessaloniki, and results are drawn for the feasibility of strengthening the reinforced concrete building stock in this city.  相似文献   

舟山国家石油储备基地堆载预压加固效果分析   总被引：5，自引：0，他引：5  

朱向荣  李振  王金昌 《岩土力学》2008,29(4):881-886

介绍了舟山国家石油储备基地试验区软基堆载预压大型现场试验结果,根据现场试验测得的数据,分析了软土地基堆载预压下沉降变化规律、分层沉降变化规律、深层土体位移变化规律、超静孔隙水压力变化规律,进一步探讨了根据应力和应变分析得到的地基固结性状,其中通过应变分析得到适用于储备基地的沉降经验系数m。结果表明,打设塑料排水板结合堆载预压处理软弱地基具有良好的效果。  相似文献   

PVC-U塑料管在浅层地热能地下水资源开发工程中应用与研究     

卢予北 《探矿工程》2008,35(11):1-6

PVC-U塑料管具有耐腐蚀、不结垢、质量轻、使用寿命长等特点。将其应用于浅层地热能开发和供水管井工程中,不但可以解决金属井管腐蚀破裂、结垢和水源热泵回灌难等问题,而且还减少了水井维修费用、延长其使用寿命。结合河南郑州实施的437、400 m两眼浅层地热能开发和供水管井示范工程实践,详细论述了PVC-U塑料管成井工艺、存在问题及解决方法的研究成果。  相似文献   

钢筋混凝土梁结构断裂损伤诊断方法     

周尚志  王丽华刘瑛 《海洋工程》2005,23(4):47-51

提出一种基于BP神经网络的结构破损诊断方法,该方法以结构破损前后柔度的变化作为破损诊断网络输入,为了解决由于系统响应样本数据空间分布不均匀对网络收敛速度及网络诊断影响问题,对网络训练样本采用广义空间格点进行了交换,模拟算例及应用实例均表明,本文方法能准确诊断结构破损位置与破坏程度,是一种有效的结构破损诊断方法.  相似文献   

Full-range nonlinear analysis of fatigue behaviors of reinforced concrete structures by finite element method     

Song Yupu  Zhao Shunbo  Wang Ruimin  Li Shuyao 《海洋学报(英文版)》1994,13(1):143-154

Ｆｕｌｌ－ｒａｎｇｅｎｏｎｌｉｎｅａｒａｎａｌｙｓｉｓｏｆｆａｔｉｇｕｅｂｅｈａｖｉｏｒｓｏｆｒｅｉｎｆｏｒｃｅｄｃｏｎｃｒｅｔｅｓｔｒｕｃｔｕｒｅｓｂｙｆｉｎｉｔｅｅｌｅｍｅｎｔｍｅｔｈｏｄ￥ＳｏｎｇＹｕｐｕ；ＺｈａｏＳｈｕｎｂｏ；ＷａｎｇＲｕｉｍ...  相似文献   

海洋钢筋混凝土结构牺牲阳极保护系统电极行为的研究     

季明棠  倪湘毓  杨芳英 《海洋与湖沼》1995,26(3):275-280

于１９８９－１９９０年在室内条件下，用牺牲阳极保护浸泡于海水中的多种钢筋凝土试件测试不同试件中钢筋极化与阳极布局、涂层质量，涂层厚度及试件浸水情况的关系。结果表明，牺牲阳极能有效地保护全浸海水中的混凝土试件，对间断浸淋海水的试件也有一定的保护作用，通过改善阳极安装工艺，保护作用可望提高；电偶电流在各阴阳极上的分布将随涂层质量，涂层厚度和试件浸水情况不同而异，回路中电阻和电极极化情况是影响电流分布的  相似文献   

Elasto-Plastic Analysis of Tubular Joints of Offshore Platforms by Finite Element Method     

Chen Tieyun Zhu Zhenghong Professor  Dept. of Naval Architecture  Ocean Engineering  Shanghai Jiao Tong University  Shanghai Lecturer 《中国海洋工程》1991,(1)

The plastic node method is reformulated by the variational principle and is applied to elasto-plastic finite element analysis of tubular joints, eventually including the effect of internal and external gussets, stiffener rings, etc., if necessary. Four different joints are studied here in detail for the elasto-plastic behavior, the strain at the hot spot, the strain concentration factor around the intersection line, and the propagation of the plastic region with loading up to collapse in order to determine the ultimate strength, safety factor, and development of the plastic field. The present results are in good agreement with the experimental results.  相似文献   

Fatigue Behavior of Plain Concrete Under Biaxial Compression: Experiments and Theoretical Model     

ZHU  Jin-song 《中国海洋工程》2003,17(4):617-630

The effects of different lateral confinement stress on the fatigue behavior of and cumulative damage to plain concrete are investigated experimentally. Eighty 100 mm x 100 mm x 100 mm specimens of ordinary strength concrete are tested under constant- or variable-amplitude fatigue loading and lateral confinement pressure in two orthogonal directions. A fatigue equation is developed by modifying the classical Aas-Jakobsen S-N equation for taking into account the effect of the confined stress on fatigue strength of plain concrete. The results of variable-amplitude fatigue tests indicate that the linear damage theory proposed by Palmgren and Miner is unreasonable in the biaxial stress state. A nonlinear cumulative damage model that could model the effects of the magnitude and sequence of variable-amplitude fatigue loading and lateral confinement pressure is proposed on the basis of the evolution laws of the residual strains in the longitudinal direction during fatigue tests. The residual fatigue life predic  相似文献   

混凝土的渗透性与耐久性   总被引：7，自引：0，他引：7  

李淑进  赵铁军 《海岸工程》2001,20(2):68-72

渗透性是混凝土耐久性中最重要的内容。论述了混凝土耐久性的影响因素、研究方法 ,以及混凝土渗透机理和渗透性与耐久性的关系。  相似文献