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20 June 1988, Volume 7 Issue 3 Previous Issue    Next Issue

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Boundary Element Modeling of the Stress Singularity at the Front of Surface Crack Zhou Yufeng, Zhang Yongyuan 1988, 7(3): 1-8.  Abstract ( )   PDF (501KB) ( )   A new boundary element method for the analysis of surface crack is proposed in this paper. The advantage of the boundary integral equation derived from this model is that only the surface of the crack need to be discretized. The singularities of stress in the boundary layer of half-elliptical surface crack are solved by using the new model. Related Articles | Metrics

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Experimental Investigation of Anti-cracking Behavior for Inclined Section of Simple Partially Prestressed Concrete Beams Zhou Zhixiang, Jiang Bingzhang 1988, 7(3): 9-17.  Abstract ( )   PDF (608KB) ( )   Based on the results of shear test of 50 beams, this paper describes the behavior of beams with different degree of prestress, shear span to depth ratio, concrete strength and shape of section under loading and emphatically analyzes the influence of degree of prestress,shear span to depth ratio and shape of section upon the diagonal cracking load. A formula for estimating the diagonal cracking load is proposed and a comparision between the formula in the paper and these in some other reference is made. Related Articles | Metrics

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The Analysis of Gluing Axiom Lu Liandi 1988, 7(3): 18-21.  Abstract ( )   PDF (311KB) ( )   This paper describes the meaning of gluing and the basic assumptions of its calculation. The analysis of gluing axiom is carried out by analyzing the tensile membeis of reinforced concrete simultaneously. The different gluing axioms of prestressing cables for pretensioning and postensioning are analyzed and compared with each other. Related Articles | Metrics

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Rediscussion on New Trends in Cable Stayed Bridge in the World Fan Lichu 1988, 7(3): 22-30.  Abstract ( )   PDF (590KB) ( )   In this paper, recently constructed long-span cable stayed bridges are surveyed. The development of cable stayed bridges can be divided into three stages. At present most bridges are built according to the second and third stage of development. The third stage brought in the bridges with very closely spaced stay cables and slender deck. Some examples of competitive bidding for cable-stayed bridge are briefly described Related Articles | Metrics

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The Curved Thick Shell Element Method for Analysis of Dynamic Property in Curved Plate Arch Bridges And Its Test Wu Bo Chen, Xiangbao 1988, 7(3): 40-49.  Abstract ( )   PDF (588KB) ( )   This paper put forward for the first time an analysis of the dynamic property in curved plate arch bridges with curved thick shell elements. The performance of the curved thick shell, elements has been compared with the results obtained from the 3D-solid element analysis, and the experimental results. It shows that the curved thick shell element analysis of curved plate arch bridges is quite valid. The dynamic property of the curved plate arch bridges may be analyzed with the IBM personal computer. Related Articles | Metrics

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The Elastic Constants of Hollow Sphere-Fiber-Reinforced Composite Materials And Their Technical And Econamical Effect Zhang Peiyuan 1988, 7(3): 50-55.  Abstract ( )   PDF (416KB) ( )   A great many variety of hollow sphere would be noted and more and more used in composite materials which contain the fiber-reiuforced plastic.lt accounts for that the hollow spheres,as a new component part,may improve the module and reduce the weight and cost of the articles.In this paperthe auther presents a model and formula of predicting the elastic constants,improving the use of a variety of these new componets.The auther predicts that it is interesting that a great many variety of hollow sphere not only for improvement of rigidity of the material but also reducing the weight and cost of the articles.However,these advantages would be considerable only when the volume fraction of fiber had not been contained more than that of matrix. Related Articles | Metrics

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Calculation And Analysis of Shear Stress in Prestressed Variable Depth Beams Wan Guohong, Huang Shengwu 1988, 7(3): 56-69.  Abstract ( )   PDF (783KB) ( )   Based on the strength theory of materials, some formulas for shear stress calculation in prestressed variable depth beams are introduced and demonstrated in this paper. The physical concept of each term in the formulas is clarified. An analysis, a comparision and evaluation for all formulas are given. At the same time, shear stress distribution is studied. Finally the theory and formula of bend-shear stress calculation in prestressed thin wall box beams with variable depth are introduced and it is indicated that other formula is inadequate. Related Articles | Metrics

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Experimental Research on Ultimate Shear Strength of Partially Prestressed Concrete with Considering Degree of Prestress Xiao Guanghong, Jiang Bingzhang 1988, 7(3): 70-83.  Abstract ( )   PDF (861KB) ( )   This paper presented the test of 50 beams of partially prestressed concrete and 82 datum of the ultimate shear strength. Based on these results, the authers studied the effects of the degree of prestress and the shear span to depth ratio on the ultimate shear strength. The different degree, shear span to depth ratio and stirrup were considered. The empirical formula of ultimate shear strength was proposed. the formula given in the paper can also be used for the case of reinforced concrete and full prestressed concrete by introducing a degree of restressing. Finally, a design formula was proposed and compared with the provisions used both in China and other countri es. Related Articles | Metrics

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A Direct Method for Solution to Problems of Time-continuous LQR Via BPFs Xu Maozeng 1988, 7(3): 84-95.  Abstract ( )   PDF (656KB) ( )   In this paper a new method for solution to the problems of the time-continuous linear quatratic regulator (LQR) via block-pulse functions (BPFs) is proposed. The basic idea of the method is that a problem of the LQR is first converted to a special kind of problem of multi-stage dynamic programming by using some properties of the BPFs and introducing some implemental quantities. And then a recursive algorithm for solution to the latter is derived by the well-known principle of optimality. Unlike the methods used in literatures[l],[2],[3],[4],the method presented here avoids computing the inverses of matrices with dimension 2n×2n where n is the dimension of the dynamic equation under study. An illustrative example is given, Related Articles | Metrics

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A Cyclic Forecast Method of Dynamic Systems Chen Guozhen, Xu Maozeng 1988, 7(3): 96-101.  Abstract ( )   PDF (437KB) ( )   In the forecast of dynamic systems, future values of system input varibles are often unknown, and influenced by those of system output varibles in the way of feedback. Such forecast problems often occur in social-economic systems. The forecast of freight quantity to be transported is such an example, which we met when we studied the problem of transportation in the Three Gorges on Yangtze River. In this paper,the cyclic forecast method is proposed to solve such problems.The general formof discrete time system model and the forecasting procedure are given.The forecasting error is analysed and the results are heuristic. Related Articles | Metrics

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On A Class of Fredholm Type Integro-differential Equations in Banach Spaces And Its Application Zheng Quan 1988, 7(3): 102-108.  Abstract ( )   PDF (401KB) ( )   In this paper, we prove the existence of solution for a class of Fredholm type integro-differential equations in Banach spaces. In application, we utilize the above results to study the existence of solution of boundary value problems for nonlinear ordinary differential equations of second order in Banach spaces. Related Articles | Metrics

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Generalized Principal Components Regression in the Gauss-Markov Models with Multi-collinearity Yang Hu 1988, 7(3): 109-115.  Abstract ( )   PDF (490KB) ( )   In this paper we detail the multi-collinearity and principal components in the Gauss-Markov models, and propose a generalized principal components regression estimate which unifies the results in[3] and[13]. Related Articles | Metrics