Applied Mechanics and Materials Vols. 501-504

Abstract: The dynamic characteristics of the Qiantangjiang rail-cum-road steel truss bridge is to analyzed by the Beam elements Midas model, beam-Plate element Midas model and plate element Ansys model, and the calculated results are compared with the field experiment data. The natural frequencies and mode shapes simulated with the plate element Ansys model are much closer to the experimental ones, indicating it can more accurately simulate the dynamic characteristics of steel truss structure. The results can provide a reference for modeling the steel truss bridges, and as the foundation of further static and dynamic analyses.

Abstract: In order to understand the actual working condition and the bearing capacity of the bridge, the static and dynamic tests were carried out. By measuring the stress-strain and deformation of the main control sections of the bridge, we can determine if the design expectations of the structure and its actual working performance were consistent. Through dynamic load test motivating the bridge, we got the dynamic structure factor and vibration characteristics.

Abstract: The concrete creep effect is a peculiar phenomenon of concrete material, it has a significant effect on the deformation and internal force redistribution of concrete member, besides, it may cause the loss of prestress , it may have serious consequences especially on complex structure such as long-span bridges. So it must be considered in bridge design and construction. Based on the subject of CYSG deformation monitoring and 32m precast PC simply supported box girder, the method of creep test has been researched and determined in this paper firstly, then the laws of the development of the creep has been summarized, and the influencing factors of concrete creep has been concluded. Using the finite element software ANSYS and the APDL language, theoretical analysis of creep has been carried on in this paper. In conclusion, This paper analyzed the influencing factors of concrete creep and provided the basis for long-term deformation control of creep by comparing the theoretical results with the experimental data.

Abstract: Based on the finite element theory and ANSYS software, the linear and nonlinear analysis were conducted on the stress situation of the continuous joint on the simply supported T beam bridge with continuous deck by applying different loads condition. The force influence factors of the deck continuous section were studied by changing parameters, and the corresponding improvement measures were put forward. The design and construction theoretical basis for the simply supported T beam bridge deck pavement were obtained and could provide reference for the related person.

Abstract: This paper investigates the evolution characteristics of existing bridge safety based on algebraic topology and image analysis. Through the calculation of betti numbers of cross section in bridge pier binarization images, evolution curve of betti numbers time series is observed, which reflects the changes in internal structure of bridge piers, due to the variation of external environment. The analysis results show that when the evolution trend of the betti number appears a smooth change, the bridge pier is in safe condition, and when betti number curve appears sudden fluctuations, the internal structure of piers presents some changes. This study has positive significance for long-term monitoring of bridge safety.

Abstract: Based on the theory of fatigue fracture of metals, quantitative analysis method was proposed for fatigue strength of cables of cable bridges and conclusions were reached through analysis of calculation formula: the analysis method of stress fatigue life was able to consider the section dimensions of the cables, plasticity of the material and stress ration caused by external loads and other factors which affect the fatigue life. This analysis theory was correct which took into consideration of relatively overall factors and was a better way to analyze the cable fatigue life. Meanwhile, the design of fatigue strength of bridge cables should adopt the theoretical fatigue limit represented by equivalent nominal stress amplitude as the design value of fatigue strength of cable. The theory represented by equivalent nominal stress amplitude considered the influence of stress ratio on fatigue life of cables caused by external loads. Compared with traditional method of fatigue strength estimate, with sufficient theory basis and overall consideration of factors, the results of this method were more reliable.

Abstract: Cable-stayed suspension bridge is an unconventional bridge type with a bridge typology based on the combination of both cable-stayed and suspension systems. In this paper, the static behaviors of cable-stayed suspension bridge were revealed from the viewpoint of the structural deformational characteristics under different kinds of live loads. To more clearly illustrate these characteristics, the simplified analytical method based on the simplified analytical solutions for cable-stayed bridges and suspension bridges were adopted in the derivations. Furthermore, the simplified material cost model based on allowable stress method for cable-stayed suspension bridge was also proposed for researchers and designers to adopt in preliminary design stage.

Abstract: Based on the change coefficient of modal flexibility curvature, an experimental research on damage recognition of cable-stayed bridge was conducted. The working conditions are introduced, as well as the design and manufacture of the model that can serve as an important guide to the similar experiments. In the design of this experiment, the optimization of cable tensions and the sensor placement optimization were discussed and the suitable methods were chosen and verified. The results verify the sensitivity of the change coefficient of modal flexibility curvature and compare the identification ability on different parts of the same damage location. In addition, how the number of modes required affects the change coefficient of modal flexibility curvature was discussed and the proper number is given.

Abstract: This paper studies the diseases of the Concrete Filled Steel Tubular (CFST) arch bridges in Guangxi. More than 10 CFST arch bridges have been built in this region in the past 20 years, and now some of them are working with diseases. According to the investigation, the diseases of the CFST arch bridge including structural diseases, materials diseases, environmental diseases and other typical integrated diseases are caused by different reasons. It is suggested that more measures should be taken to prevent the emergence of new diseases and further development of existing diseases.

Abstract: Finite element model of the background tied-arch bridge was established and analyzed. Meanwhile, mechanical performance and stability of it under several kinds of simulate structural defects and damages were studied. Some typical damage and influence factors were presented in the beginning. Then, based on the finite element model, the distribution of suspender force corresponding to the simulated defects and failure was calculated respectively. At last, the first class stability safety factor under the combination load was calculated as well as the second class nonlinear stability safety factor under structural arch rib defect. Results of above calculation imply that, suspender forces gained a stronger sensitivity to vertical defect than to transverse defect. While, short suspenders were believed to be more sensitive to lineation defect than long ones according to calculation results. Additionally, secondary inner force of short suspenders was much more intensive than in long ones. The result also tells that lateral wind did bad to stability. Lift wind, contrarily, made a little positive contribution to structures in-plane stability. Simulated structural defects were supposed to aggravate the second class stability safety factor under geometric nonlinear condition.