Applied Mechanics and Materials Vols. 438-439

Abstract: In order to understand the overall mechanical characteristics of a steel-concrete composite box girder bridge, static and dynamic tests were carried out. According to the results of tests and calculations, its bearing capacity and working performance were evaluated. The results show that the stress and deformation at control cross-section of the bridge meet design requirements under the static load, the vibration frequency and impact coefficient consistent with the theoretical calculation results under the dynamic load.

Abstract: Due to geological conditions at abutment, working mechanism and economy, a prestressed concrete bridge with double cantilevers is designed. Main dimensions and drawings are introduced and static analytical results of prestressed concrete cantilever bridge are discussed. The numerical model was built by the integrated solution system for bridge and civil Engineering-MIDAS/Civil. The main loads which affect internal force and deflection at key sections of bridge are studied, such as mid-point, support point and free end of cantilever bridge. The rules which loads affect internal forces and deflections are revealed. The results show that dead weight is an important load to control internal force and deformation of bridge with double cantilevers. The design and numerical results would give some references to the optimization of similar bridges.

Abstract: Monitoring and controlling of vertical construction for main arch ribs is most important for concrete-filled steel tube (CFST) arch bridges due to high risk. Controlling the difference of elevation between the two main arch ribs has direct influence on the mechanical behavior of lateral brace, towers and temporary hinges at arch abutments of main piers. Therefore, transverse synchronization control is the main priority in vertical rotating construction phase. Taking a half-through CFST arch bridge in Shijiazhuang City as an example, this paper make a study of transverse synchronization control of the two main arch ribs during vertical rotation. The finite element method (FEM) software-Midas is employed to simulate the main arch ribs in rotation construction phase, and maximum value of the difference of elevation between the two main arch ribs is obtained to offer reference and basis of vertical rotation construction of this bridge.

Abstract: In order to ensure the safety of long-span continuous prestressed concrete girder bridge constructed by hanging cradle method, a pre-camber is always made to reduce shrinkage and creep in the process of post-operation, the late loss of pre-stressed, deformation produced by live load and so on. Combining with Qinhe Bridge, how to install the pre-camber is studied in this paper. The maximum pre-cambers and their locations of every span of Qinhe Bridge are determined by the method of standard JTG D62-2004 with the finite element analysis software MIDAS/CIVIL. The results show that the final pre-camber curves calculated by the method of standard JTG D62-2004 and quadratic parabolic method have cusps, which cannot meet the standard requirements for the smooth of the bridge. But the slop of the final pre-camber curve calculated by cosine curve at the maximum pre-cambers and the pier top is zero, and the slop of curve from pier top to the mid-span is small, which satisfy the standard requirements for the smooth of bridge. Therefore, the final pre-camber curve should be calculated by cosine curve.

Abstract: In order to ensure the safety of the scaffolding of the home block for hanging cradle construction, this paper makes use of probabilistic limit state method, and carries out the checking computation. According to the actual drawings of the Qinhe bridge and the actual load case, the analytical model is established through the finite element analysis software MIDAS/CIVIL. The results show that the slant tube may be flexural buckling, and the stress of side standing tube is over the design strength of material, so that there is potential danger of the scaffolding. After the horizontal tubes were installed along the boundary of scaffolding, the stresses of all tubes are less than the design strength of corresponding material.

Abstract: Long span bridges have two main section forms including streamlined closed steel box girder and twin steel box girder. In order to compare the wind-resistant capacity, the finite element software ANSYS is adopted to establish the calculation structural models of Third Bosphorus Bridge respectively with two kinds of sections in the same width. According to the analysis of the wind-induced internal force and the flutter stability, the respective advantages of the two section forms in terms of wind-resistant capability are discussed. The analysis results could be used as reference in the section design of long span bridges.

Abstract: The pretreatment conjugate gradient method (PCGM) is proposed to improve the ill-posed problem of moving force identification. Compared with the time domain method (TDM), the identification accuracy of the time-varying bending moment responses is more obviously improved. Meanwhile, the pretreatment matrix is very important to the PCGM because it affects the identification accuracy and robust noise immunity as well as ill-posed problems identification to some extent, choosing proper preconditioned matrix can effectively improve both of identification accuracy and efficiency of the PCGM.

Abstract: Combined with the station of Maritime University ~ High-tech Zone tunnel project, this paper analyzes each section of the measured data on the spot to determine the surface subsidence. Research results show that the soil geological conditions of different effects on the subsidence are obvious, but shapes which formed by the settling tank are similar. Meanwhile, combining the construction of advanced small pipe grouting and shotcreting concrete technical measures, the surface subsidence control of the project abides by the surface subsidence rule of the shallow tunnel construction and deformation control.

Abstract: Diseases such as segment cracks, damage, dislocation, water leakage often occur during the construction and operation process of shield tunnel, which will threaten the safety of running trains and shorten the maintenance cycle and service life. Based on previous research on shield tunnel diseases, the paper makes an analysis of the detection methods, causes of diseases, evaluation and repairment. Combining with the personal understanding of practical projects, the authors put forward some problems about the current research.

Abstract: This paper based on Chaoyang tunnel by bench method excavation, using the finite element numerical simulation method, simulates the surrounding rock displacement of soft rock tunnel and the stress characteristics of supporting structure to get the various stages of tunnel surrounding rock stress, strain and the internal force changes of tunnel supporting structure. After the analyses of the numerical simulation results and field monitoring measurement data, the safety and rationality of the method are determined. The research provides certain reference for highway tunnel design and construction.