Applied Mechanics and Materials Vols. 256-259

Abstract: Loukouni bridge is a deck type arch bridge with box section which is a part from the second stage of the 1st national road project of the Republic of Congo. This paper focuses on the optimization design analysis of the Loukouni bridge to make it more economical and reliable. The optimization analysis is implemented by ANSYS and contains two parts. One part focuses on the whole shape of the arch and try to optimize the arch axial coefficient. The other part considers the optimization of the size of the box section. The analysis results could provide useful suggestions for the design of Loukouni bridge and related steel arch bridges.

Abstract: This article studies on the effect of magnetic field strengths on the flow field in a liquid bridge under zero gravity. The mass conservation level set method is used to track the two-phase interface. The results show that inhibitory effect of additional axial magnetic field on thermocapillary convection within liquid bridge is obvious, and this kind of inhibitory effect increasing as the magnetic field strength is strengthened.

Abstract: Due to over length and weight of the girder segment, the main bridge steel box girder of Chongqi Bridge adopts large segment integral lifting erection method; two sets of large floating cranes are needed for hoisting. According to the water environment condition at site, select the lifting equipments to research on; conduct restrict checking on the lifting weight, height and amplitude; new automatic balance type lifting sling structure form is adopted during lifting erection to make sure the stress on each lifting point is balanced; conduct optimization design onto the lifting points; aimed at lifting erection of large segments, use ansys to establish large solid simulation model for finite element analysis so as to guarantee safety of steel box girder structure during lifting erection of large segment.

Abstract: Due to the benefits of having a larger span length, a more elegant structural shape, better adaptability and financial feasibility, the use of self-anchored suspension bridges as solutions in the engineering industry has been widely adopted. Based on the theory of 3D flutter analysis, this study chose to analyze an entire bridge. The effect of initial wind attack angle and static wind loading on the flutter stability of self-anchored suspension bridge was investigated. The results show that the critical flutter wind speed varied noticeably with different initial wind attack angles, and that an angle of +3° gave the most adverse state. Moreover, when static wind loading was considered, while changes in structural vibration characteristics showed little influence on the flutter stability of self-anchored suspension bridge, the added attack angle on the main girder affected the flutter stability remarkably.

Abstract: A research based on Jiashao Bridge is carried out to reduce buffeting response under strong wind of the control section of main girder of the longest cantilever state and to ensure the security of the bridge during the construction period. A method that the ends of cantilevers are connected with several temporary damping cables is considered as wind-resistant measure. 4 modes with different damping cable arrangement are supposed, and the wind-resistant effect corresponding to the 4 modes are compared by FEM analysis. A mode with the best wind-resistant effect and economical meanwhile is selected out and local optimization is added to the selected mode. Some valuable conclusion obtained from the research could be adopted in Jiashao Bridge and the similar projects.

Abstract: A FEA program using 8 nodes and 40 freedoms degenerated solid shell element was developed to analyze the spatial stress of long span prestressed concrete box girder bridges during construction stage and finished stage. The maximum principal tensile stress positions on box girder section and shear lag coefficient were researched according to spatial stress results. It presented suggestions on prestressed concrete box girder bridges anti-crack design.

Abstract: In the paper, relying on the full-scale model test of embedded pile cap of the HZM Bridge, the method of combining the theoretical calculation analysis and in-situ monitoring test are used to study the slope stability and over-break depth of foundation excavation. In the theoretical calculation analysis, an empirical formula of the Hydtology of Sea-port is adopted for the over-break depth while the G-slope software is for the safety factor of slope stability; in the in-situ monitoring test, the single-beam is used for the topographic survey underwater at random after the foundation excavation. Analysising on the theoretical calculation analysis and the result of in-situ monitoring test, proper slope ratio and over-break depth of pile cap foundation excavation is put forward to provide key construction parameters for the main project of the HZM Bridge.

Abstract: The surface-layers have very high water content and low bearing capacity, so far to be the very soft clay foundation, which come from the reclaimed land in project of reclamation. It is difficult to improve the very soft clay foundation by traditional vacuum preloading. A new method named surface soft soil improvement is presented in this paper, which can make the soft clay foundation to be improved in preliminary. Once forming the hard coat layer, the foundation may reach the needs of further construction. In the construction technology, the horizontal filter pipe net is used to instead of the sand bedding course. By laying of woven cloth and non-woven geotextile over the surface of reclaimed silt, installing PVDs by manpower becomes possible. Besides, the vertical PVDs all are connected with the horizontal filter pipe net directly, that makes a whole spatial drainage system. The loss of the degree of vacuum is decreased, and the improvement is increased. Thus, this construction technology is as a reference to the large scale engineering construction and similar projects.

Abstract: In recent years, as the rapid development of highway construction and the increase of road traffic mileage of China, the highway traffic safety smooth has become an essential question of highway projects. In this paper, the second line which was modified by fiber slurry of S211 provincial highway construction engineering as the test prototype. We have calculated the optimum mixture ratio of the slurry mixture which was modified by fiber in the laboratory. In this condition, the shear performance, anti-fatigue performance, water damage resistance and mechanical impact resistance performance of the mixture have improved compared with the mixture without fiber modified. At the same time, the same section road with fiber modified slurry mixture and without fiber modified slurry mixture have been compared and analyzed by finite element method based on the ANSYS. We could draw some basic conclusions: The value of pavement deflection and the tensile stress of fiber modified slurry layered road have reduced compared with the slurry layered road without fiber modified.

Abstract: Semi cover and cut construction have been widely used in solving the traffic problem in narrow area. The main issue of this method is to make sure the safety of temporary road and bridge system. The paper is based on a subway station, it simulates foundation pit with different width-depth ratio through finite element methods and analyzing different pile parameters. The research shows: (1) When use different width-depth ratio the shape of basal heave and the position of maximum value are different. (2) When there is a plastic uplift, the positions of “double-peak” don’t change with the width. (3) Increasing the length of pile is better than increasing the diameter of pile to decrease the upheaval of temporary road slab.