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20 April 2008, Volume 27 Issue 2 Previous Issue    Next Issue

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Mechanic Analysis on Vertical Prestressing Bar to Continuous Rigid Framed Bridge CHEN Yan-ru, ZHOU Shui-xing, CHEN Zhan-rong 2008, 27(2): 173-176,184.  Abstract ( )   PDF (363KB) ( )   Vertical prestressing bars play a great role in controlling the principal tensile stress of webs. According to existing norms, the ratio of the vertical prestress loss to different length of the vertical prestressing bars is analyzed. In view of the current design of the delay tensioning vertical prestressing bar, the impacts to the continuous rigid-framed bridge by each of the three different delay tensioning methods is analysed, and the reasonable prestressing time is given based on the analysis. The reasons for the webs in a single vertical prestressing bars under the stress distribution and on the edges of web tensile stress are analyzed in detail, by establishing the detailed FEM simulation model of webs, and then the advice how to avoid stress on the edge of tectonic is given. Related Articles | Metrics

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Study on Stress Transfer in Steel-Concrete Joint of Hybrid Arch Bridge YAO Guo-wen, ZHOU Duan-ming, ZHOU Zhi-xiang 2008, 27(2): 177-180,220.  Abstract ( )   PDF (410KB) ( )   It is very important for the steel and concrete in the hybrid structures to integrate effectively and carry loading reliably. The safety and performance of steel-concrete hybrid arch bridge depend on the design of its pivotal steel-concrete hybrid joint. Stress distribution of three kinds of the steel-concrete hybrid joint is simulated in FEM. And the stress transfer rules are further probed in steel, hybrid joint and concrete. The results show that the high stress in steel box will be gradually and effectively transferred and dispersed into concrete box after increasing the number of ribbed stiffeners, the area of bearing plates and the end section of concrete box. In that case the stress concentration will be decreased greatly in the steel-concrete hybrid joint. Related Articles | Metrics

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“Two Stage Method” of Cable Tension Optimization for Short/Medium Span Cable-Stayed Bridges CHEN Zhan-rong, LIU Qi, ZHOU Shui-xing 2008, 27(2): 181-184.  Abstract ( )   PDF (271KB) ( )   Based on the theory of Influence Matrix, with the constraint optimization and the positive disposition analyses as its core, the "Two Stage Method" which is used for the cable tension optimization on short or medium span cable-stayed bridges is proposed. And then, an example is used to verify the correctness of this method. It can get the reasonable cable tensions without inverse analysis. This method can accelerate the solution procedure of cable tension optimization and it would be useful in the analysis of both the finished dead state and construction stage in short/medium span cable-stayed bridges. Related Articles | Metrics

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Improvement of the Least-Squares Fitting Method to Calculate Bridge Design Flow PENG Li-li, ZOU Yi-Song, CHE Jing 2008, 27(2): 185-187,212.  Abstract ( )   PDF (311KB) ( )   At present the bridge hydrology is mostly calculated in expeziential statistic. This calculating method makes use of Pearson Ⅲ curve as the theoretical frequency curve to draw appropriate lines. The method needs to compute many times to find the most suitable answer and has to draw theoretical frequency curve and experience frequency points. In order to avoid such shortcomings and improve the computational efficiency, the curve fitting method had been proposed. Hyperbolic functions as the basic functions for the least-squares fitting method are used to displace power functions, which is commonly used as basic functions to further improve the computational accuracy and efficiency. Related Articles | Metrics

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Structure Reliability Calculation Method Based on Finite Element-Artificial Neural Network-Monte-Carlo XU Yong-jiang, XING-Bing, WU Jin-liang 2008, 27(2): 188-190,216.  Abstract ( )   PDF (330KB) ( )   According to reliability theory,based on Finite Element, Artificial Neural Network and Monte-Carlo (F-A-M),a new structure calculation method is developed. First,finite element analysis model is built up,inputting values of the structural parameters and loading at random,and then response of the structure is recorded.The number of the record is limited,but it is enough to train the Artificial Neural Network (ANN). After ANN being trained with the training samples,a highly nonlinear mapping relationship between the efficacy and response of the structure is gained. Making use of the generalization capability of ANN,sufficient structural response value is developed at random. Then the reliability of the structure is calculated by the Monte-Carlo method. This approach which not only makes full use of the merit of ANN and Monte-Carlo,also makes the calculation more effective, provides a fresh method for the reliability of structure. Related Articles | Metrics

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Analysis on Limitation of Current Standard about Bridge Aerodynamic Admittance Theory ZHUGE Ping, LU Peng-zhen 2008, 27(2): 191-194.  Abstract ( )   PDF (320KB) ( )   Aiming directly at the limitations of aerodynamic admittance function of current sdandard, and in order to describe the effects of aerodynamic admittance function to buffeting, various factors that affect the aerodynamic admittance are put forward by overall theoretical analysis. The limitations of current aerodynamic admittance function are tested by programming and wind tunnel test. Then it is pointed out sequentially that a systematic aerodynamic admittance theory is necessary. The results provide theoretic bases for better assurance of the buffeting theory and the project applications. Related Articles | Metrics

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Theory and Application of Construction Mechanics to Big-span Bridge LUO Ling, CAO Shu-shang, KUANG Jian 2008, 27(2): 195-199.  Abstract ( )   PDF (369KB) ( )   Construction mechanics which mainly studies behaviour and characters in construction stage is a development on the basis of engineering mechanics. The formation of bridge construction mechanics theroy promotes the development of construction techniques and becomes the basis of construction control techniques in big-span bridges. Bridge construction mechanics theory has many achievements, such as calculation method of superposition of beam dead load endogenous force, calculation method of superposition of deflection, calculation method of creep and effective prestressing force and most dangerous state and temperature influence in construction and thermal stress of cement concrete at an early stage, determination of construction order and methods,and so on. A big-span continuous rigid frame bridge is taken as an example which shows the application of construction mechanics. Related Articles | Metrics

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Study on Internal Force Distribution Method of Co-Section for Arch Bridges Strengthening HUANG Hai-dong, XIANG Zhong-fu, LIU Jian-feng, LIN Xiao-feng 2008, 27(2): 200-203,247.  Abstract ( )   PDF (344KB) ( )   It's common to strengthen arch bridges by enlarging section, and the combined section belongs to the "Two-Stage Loading Composite Structure" in mechanics of characteristics. The internal force distribution method of co-section is ratiocinated on the base of assumption of the plane section, and is used in the design of arch bridges strengthening. It can be reference for the same kind of bridges in calculation and strengthening design. Related Articles | Metrics

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Study on Duplicate Arch Bridge Reinforcement and Protection GUO Rui-dong, ZENG De-rong, LI Jie 2008, 27(2): 204-207.  Abstract ( )   PDF (291KB) ( )   Taking the process of the reinforcement and protection of a duplicate arch bridge as an example, it is super-posited by Guojiaolong old arch bridge in Shizhu in Chongqing and one modern arch bridge. Common damages and causes are found through investigating and computer model discussion. The reasons of protection are analyzed and methods of bridge reinforcement are provided. Related Articles | Metrics

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Model's Establishment and Analysis of Engineering Life Cycle Cost for Bridge Rebuilding Project BAI Hong-tao, WANG Fu-min 2008, 27(2): 208-212.  Abstract ( )   PDF (396KB) ( )   Making use of some basic principles of technique economics, on the base of the funds' time value, every possible cost of the reinforcement and the reconstruction for the highway and bridge which happened during the life cycle has been analyzed through comparing with others; what's more, a comparative scheme model has been made, too. At last, an example is given to show the process of comparing schemes, which aims to give some references to select a reasonable reconstruction scheme for the current highway and bridge. Related Articles | Metrics

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On Bridge and City View CHEN Zheng-bin 2008, 27(2): 213-216.  Abstract ( )   PDF (362KB) ( )   By focusing on the problems in the design of bridge appearance, the relationship between bridges and city view is analyzed, and the idea that visual aesthetic value of bridge should be taken into consideration when an urban bridge is designed has been put forward. Related Articles | Metrics

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Discussion on Vehicle Flow Density Factor in Tunnel Ventilation Design HAN Xing, ZHANG Xiao, ZHANG Xu 2008, 27(2): 217-220.  Abstract ( )   PDF (275KB) ( )   The vehicle flow density factor in Specifications for Design of Ventilation and Lighting of Highway Tunnel was discussed, and the formula expressions of vehicle traveling distance in tunnel were deduced to conclude that the tunnel ventilation flow rate is not related to the vehicle flow density under certain traffic flow rate. Afterwards, the relationship between vehicle speed and traffic flow rate was discussed, which led to the point that the vehicle flow density factor is the amendment of traffic flow rate actually and its value should be reconsidered on the base of certain traffic flow theory. Related Articles | Metrics

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Application of Origin Software to Analyzing Deformation Monitoring Data during the Construction of Tunnel CHANG Bin-bin, LIU Shan-hong, HAN Jian 2008, 27(2): 221-224.  Abstract ( )   PDF (353KB) ( )   The fundamental function and application of Origin software are introduced. Plotting and non-linear curve fitting measured date can be finished by Origin software. At the same time, reliable parameters and visualized figures can be obtained. An example is taken to analyze procedure of monitoring and measurement data of Shi-long-shan tunnel. The analyzed results have been used to guide the design and construction of excavating and shoring the structure of tunnel. Related Articles | Metrics

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Optimal Analysis on Entrance Construction Scheme for Changchong Tunnel FAN Xiao-wei, XU Lin-sheng 2008, 27(2): 225-227,289.  Abstract ( )   PDF (299KB) ( )