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15 October 2014, Volume 33 Issue 5 Previous Issue    Next Issue

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Fixed End Method to Solve Shear Lag Coefficient of Continuous Box Beam Xiang Zhongfu, Jiang Junqiu, Huang Haidong 2014, 33(5): 1-6.  DOI: 10.3969/j.issn.1674-0696.2014.05.01 Abstract ( )   PDF (1066KB) ( )   Based on the superposition principle, a simple and practical calculation method to solve continuous box beam shear lag effect, that is, the fixed end method was proposed, which also met the accuracy requirements. The calculation formula of the shear lag coefficients of continuous box girder in constant load (even load) was derived. Through comparing with the results obtained from dissecting method, superposition method and finite element method, the proposed method turned out to be reliable and applicable, which was suitable for the calculation of the shear lag of thin walled box continuous beam. References | Related Articles | Metrics

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Distortional Effect of Trapezoid Single Box-Double Cells Composite Beams Zhang Yanling, Hou Zhongming, Li Yunsheng, Liu Peiye 2014, 33(5): 7-12.  DOI: 10.3969/j.issn.1674-0696.2014.05.02 Abstract ( )   PDF (1333KB) ( )   In order to reveal the distortional effect of the trapezoid single box-double cells steel-concrete composite beams, the distortional deformation mechanism was researched by the ANSYS software under the independent distortional loads which were decomposed from the eccentric vertical load, and the influence of diaphragms and slips at the bond surface on the distortional deformation were also analyzed. The main conclusions are that, the distortional deformation of the trapezoid single box-double cells composite beams includes the first anti-symmetric distortional deformation and the second symmetric distortional deformation; the end diaphragms can reduce the first distortional deformation and stress apparently, but have little influence on the second distortional effect; the diaphragm at middle span can decrease both the first and the second distortional deformation and stress obviously; the slip at the bond surface will increase both the distortional deformation and stress. So the end and middle-span diaphragms should be set in the trapezoid single box-double cells composite beams, but the diaphragms at other locations should be limited or deleted. And the slip at the bond surface should be considered in the distortional effect analysis. References | Related Articles | Metrics

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A Fine Calculation Method for the Main Cable Fabrication Length of Self-Anchored Suspension Bridge Han Xuhui, Yuan Yangguang, Chen Anyang, Zhao Jianfeng, Shu Tao 2014, 33(5): 13-16.  DOI: 10.3969/j.issn.1674-0696.2014.05.03 Abstract ( )   PDF (667KB) ( )   The unstressed length of the main cable is an important parameter that influences the finished state of bridge structure. At present, the calculation methods for the fabrication length of the main cable center strand have been well studied. Based on the previous studies, a fine calculation method for the fabrication length of the main cable was proposed. Firstly, the main cable was simulated by cable element and the unstressed length of the main cable center strand was calculated according to the finished state of bridge of target structure. Secondly, the unstressed length of each main cable strand was amended considering the actual spatial distribution of main cable at anchorage end and the cable saddle. Finally, the proposed calculation method was verified by taking a self-anchored suspension bridge as an example; meanwhile, the exact fabrication length of each main cable strand was given. References | Related Articles | Metrics

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Dynamic Characteristics of CFST Arch Bridge in Construction Stage by Tower-Cable-Arch Integration Modeling Zeng Yong, Tan Hongmei 2014, 33(5): 17-22.  DOI: 10.3969/j.issn.1674-0696.2014.05.04 Abstract ( )   PDF (1153KB) ( )   Due to the coupling effects between arch rib, cable and tower, only the tower-cable-arch integration modeling can simulate the true dynamic characteristics of concrete filled steel tube (CFST) arch bridges in construction. The current largest span CFST arch bridge — Hejiang 1st Yangtze River Bridge model (model 1) in the tower-cable-arch integration construction was established by finite element software ANSYS, and its dynamic characteristics were also investigated. And the dynamic characteristics of model 1 were compared with those of cable-arch model without the consideration of tower (model 2). Research results show that considering the tower effects, the fundamental frequency of model 1 drops by 12%, compared with model 2. Due to the coupling effects of arch rib and tower, the higher vibration modes of CFST structures are complex, the structure transverse stiffness are notably weak and CFST structures have the outstanding wind sensitivity; the high frequencies of two models are nearly close to a straight line. The change of cable forces has little influence on low frequency. References | Related Articles | Metrics

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Influence of Hydrodynamic Pressure on Seismic Response of Piers in Deep Water Zhang Jie, Zeng Jinming, Zhu Dongsheng 2014, 33(5): 23-28.  DOI: 10.3969/j.issn.1674-0696.2014.05.05 Abstract ( )   PDF (1119KB) ( )   Taking a deep water pier bridge as the research project, the linear and nonlinear analysis on hydrodynamic pressure on seismic response of deep-water piers were carried out by Morison equation and the radiation wave theory. The influence results of hydrodynamic pressure on seismic response of piers calculated by above two methods were compared and the difference was obtained. The results show that in both methods the hydrodynamic pressure increases the structure dynamic response of the piers, and the influence value obtained by the radiation wave theory method is lager than that obtained by Morison equation; nonlinear analysis methods to analyze the seismic response of the bridge should be used when deep-water bridges enter the nonlinear state under strong seismic response; adopting the hydrodynamic pressure in the specification is not safe when the water depth is larger. References | Related Articles | Metrics

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Warning Level of Large-Span Continuous Rigid Frame Bridge in Single Live Load Wu Haijun, Li Jun, Huang Youbang, Wang Qingzhen, Yue Shun 2014, 33(5): 29-31.  DOI: 10.3969/j.issn.1674-0696.2014.05.06 Abstract ( )   PDF (757KB) ( )   The status quo that the bridge security state was determined by the live load response was analyzed, and the idea that the operational state determining and warning of bridge structure were carried out by structure stress response in single live load was proposed. Based on the reliability corresponding with different live load effects, the idea that the live load standard values, frequent values and quasi-permanent values were designed as the live load threshold values of warning and judging was proposed. The stress distribution characteristics of Jiangjin Yangtze River Bridge in actual single live load were analyzed, and the warning threshold values were obtained by the calculation principle of the stress warning value in single live load, and the actual warning level of bridge in single live load was assessed. References | Related Articles | Metrics

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Bridge Crack Detection Based on Differential Equations Wang Jiawei, Yang Tingting, Jiang Wei 2014, 33(5): 32-36.  DOI: 10.3969/j.issn.1674-0696.2014.05.07 Abstract ( )   PDF (1361KB) ( )   Aiming at the shortcomings of time-wasting, high risk and cost in the traditional process of detecting the bridge crack, fractional differential theory and sobel operation were combined and applied into the image edge detection. Therefore, a novel bridge crack detection model based on fractional differential theory was obtained. The theoretical analysis and simulation results show that comparing with the current edge detecting methods, the proposed model not only can detect the edge features of the images better, but also can detect more texture detail information. Furthermore, the objective evaluation indexes, such as connectivity, false detection rate and missing rate, show that the proposed method is an effective edge detection method, which can better achieve the purpose of bridge crack detection. References | Related Articles | Metrics

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Bridge Crack Automatic Detection System Based on Stereo Vision Zhang Kaihong, Luo Lin, Yan Yu 2014, 33(5): 37-41.  DOI: 10.3969/j.issn.1674-0696.2014.05.08 Abstract ( )   PDF (891KB) ( )   Bridge crack is an important indicator for bridge safety evaluation. Aiming at the disadvantages of high error, high missing detection rate and poor real-time capability in the traditional detection method of bridge crack, the bridge crack automatic detection system based on stereo vision was designed, combining with the digital image processing technology. The system obtained the feature points’ coordinates through camera calibration, setting feature points and preprocessing the crack images, and then the binocular distance measurement principle was applied to measure the crack depth. Moreover, the length and width of the crack was calculated by the statistics of related binary image pixels. The experimental results show that the proposed system can accurately measure bridge crack’s length, width and depth online in real-time. References | Related Articles | Metrics

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Bridge Load Level and Consumption of T-Beam Prime Materials Zou Zhuyu, Wang Liping 2014, 33(5): 42-46.  DOI: 10.3969/j.issn.1674-0696.2014.05.09 Abstract ( )   PDF (923KB) ( )   The increment of the consumption of prime materials of the monolithic 30m span of the prestressed concrete T-beam model in the same safety reserve was obtained by improving the vehicle load level under the condition of unaltered stiffness. With the help of monadic linear regression and path analysis method, the quantitative relation between the consumption of prime materials (concrete, steel) of monolithic T-beam and the range of improving the vehicle load level was determined. The conclusion can help relevant departments to make decision about the plan of managing overloading and improving load. References | Related Articles | Metrics

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Epoxy Mortar and Concrete Bonding Performance of Subtropical Area Yan Guotai, Xie Jinqi, Huang Zhen, Chen Xinlin 2014, 33(5): 47-50.  DOI: 10.3969/j.issn.1674-0696.2014.05.10 Abstract ( )   PDF (621KB) ( )   Comparison tests and studies of different epoxy mortar were conducted under different working conditions, in order to ensure the bonding performance between the thin epoxy mortar grout layer and concrete bridge beams in the bridge deck pavement engineering at sub-tropical areas. The results show that the bonding strength of the primer of epoxy mortar will be affected when it is exposed to the strong sunshine; with the increase of exposure time, the bonding strength decreases significantly. However, the influence of exposure under the sunshine can be erased by grinding and cleaning the exposed primer surface. Moreover, the application of epoxy mortar without primer can ensure the bonding strength. References | Related Articles | Metrics

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Influence of Foamed Asphalt on Viscosity Reduction Based on Orthogonal Experiment Xu Dawei, Jiang Chunxiang 2014, 33(5): 51-55.  DOI: 10.3969/j.issn.1674-0696.2014.05.11 Abstract (