Advanced Materials Research Vols. 446-449

Abstract: Because the multi-box girder bridge has many advantages, such as large torsion rigidity, large load-bearing capacity, stability, fine appearance, good applicability and convenient construction, it is widely used in China. But for the defection existing in design and construction, many box girders have serious diseases. Aiming at the diseases of a viaduct bridge, the causes of diseases are analyzed and the enforcement method is proposed in this paper. The study shows that, though the box girders have large torsion rigidity, the diaphragms are designed necessarily to enhance the transversal connection between the box girders, to make them bear the loads together, to reduce their stresses and deformation, and to reduce the stresses of deck too.

Abstract: Bridge construction is the national important foundation construction of bridge engineering, is the relationship between society and economy to coordinate development of lifeline engineering. Bridge construction of rapid development, huge capital investment, the economic society of the prominent role, making it to the bridge's safety, durability, more and more attention. Based on the analysis of detection results of existing bridges, bridge on the future work state of speculation, pointed out the possible development trend for the future to provide advice, bridge maintenance. As the bridge reinforcement and reconstruction to provide accurate and comprehensive data.

Abstract: The nonlinear dynamics of a microbeam with initial axial tension is presented. The nonlocal theory with a small scale effect is applied to the problem model. Considering the axial protraction due to the transverse deformation of the microbeam, a nonlinear partial differential equation that governs the dynamic motion is derived. Explicit solution of transverse amplitude is obtained by the method of multiscale analysis. Both nonlinear and nonlocal effects are found to play significant roles in the vibration behaviors of a microbeam. The results may be helpful for the application and design of various micro-electronic-mechanical devices, where a microbeam acts as a basic element.

Abstract: The construction with hanging basket eccentric loading was studied for the cantilever casting of a 32m +48 m +32 m continuous box girder. The calculation of center deflecting angles of cantilever box girders with variable cross-section due to pure torsion was derived, and correspondingly a program was developed to calculate this formula. An analysis model of cantilever casting continuous beam bridge with hanging basket eccentric loading was established based on finite elements software, and the shear stress, the longitudinal normal stress and the combined stress of different section were analyzed under different construction process. The torsional effect due to hanging basket eccentric loading was studied and the results are helpful to guide the construction in practice.

Abstract: Abstract. This paper lists the problems during the stability analysis of long span CFST arch bridge and the corresponding modeling method. Based on the construction control of an orthotropic long span CFST arch bridge, a FEM model had been established to analysis the stability of its rib during the concrete pumping. The conclusion shows significant importance to the bridge’s construction process.

Abstract: In this study, the reliability sensitivity of the uniform strength Variable Cross-section Component is analyzed, which is the normal distribution. We propose a method for the reliability and sensitivity of the Uniform Strength Components. We may accurately obtain the uniform strength component's reliable sensitivity information on basic of random variable probability characteristic for certain situation. Through the value examples, we have studied the random variable reliable sensitivity for dangerous sections. We propose a design method with practicality for the uniform strength components.

Abstract: Baihua Viaduct which is an important transportation project of 213 National Highway was severely destroyed during the 512 Wenchuan earthquake. The fifth segment of the bridge suffered the most severe unrepairable damage, such as the rupture of the piers and falling of beams. It is worth to study the performance through the FEM dynamical analysis to explain the damage performance of Baihua Viaduct in the earthquake. The dynamical FE model of the Baihua Viaduct is established considering the non-liner properties of piers and bearings. Further the earthquake records of the nearest Wolong station is chosen to be as the earthquake excitation input to conduct the seismic analysis. The analysis shows that the results of damage position and damage degree of components of the bridge calculated by elastic-plastic dynamic analysis are close to the actual damage of Baihua Viaduct. The reinforcement ratio of piers is low, while there is not any shear failure on piers. The damage degree of elastic hinge is related with the arrangement of bearings. The girders’ displacement is much larger because there are not any anti-dropping devices on the bridge. Damage of the fifth segment of bridge may be caused by plasticity destroy of some piers.

Abstract: This paper presents the importance of stress monitoring in cantilever construction stage of concrete continuous bridge. The stress analysis model based on the actual bridge is established by the beam elements. The measuring measurement scheme and influencing factors of stress monitoring are introduced. The measured results matched the calculated results very well, which meet the needs of construction safety.

Abstract: Longitudinal assembled stiffness is the biggest problem for multi-pylon cable-stayed bridge. The longitudinal displacement and midspan deflection could be effectively controlled by setting horizontal cable at the top of pylon of multi-pylon cable-stayed bridge. This paper obtains the area and the cable force change formula of the horizontal cable through simplified model analysis of the mechanical behavior of setting horizontal cable at the top of pylon. The comparative analysis is performed by application of finie element model to discuss the effect of setting horizontal cable at the top of pylon of multi-pylon cable-stayed bridge.

Abstract: The present study uses the Global Flexibility Index (GFI), which is the flexibility matrix’s norm. For cases of ambient vibration, in which excitations are unknown, the flexibility matrix is unavailable, and the GFI cannot make out. Using the ANSYS set up and fixes the modal of structure in the condition of Vibration model to a unit, and then put the modal in the condition of Vibration model to a quality. Get natural frequencies and mode shapes, make up flexibility matrix, and then calculate Global Flexibility Index. Measure the Index regularly. With the change of the Index, judge the damage degree of the bridge. A sharp increase in the index calls for further detailed investigation for appropriate actions, such as reinforcement or maintenance.