Advanced Materials Research Vols. 1065-1069

Abstract: To explore the practical rail-bridge seismic design methods, dynamic response analysis model of the train-rail-bridge system under seismic loads was established, and the widely used simply supported track-bridge in rail transport was taken for the study. By inputting different intensity and frequency artificial seismic waves to the train-rail-bridge system, the whole history of the vehicles running through the bridge is simulated and the dynamic responses of the bridge and the vehicles are calculated. The influence of train type, seismic intensity and spectral characteristics of the earthquake were analyzed. Taking Japanese traffic safety evaluation indexes including derailment coefficient, wheel offload rate and lateral wheel-rail force as evaluation criteria, the allowed lateral bridge displacement limits and acceleration limits that ensuring train running safety under earthquake were obtained, and the bridge vibration limit curve was drawn. Using Lagrange interpolation method, the mathematical expression of the curve was worked out, which can provide a reference to rail-bridge aseismic design.

Abstract: Currently, a lot of ramps adopted continuous box girder with single column pier structure in a bridge design. If the structure is mishandled, the box girder is likely to cause overall overturn under overloaded vehicles. The cause of overturn is analyzed and calculated, and through comparing the anti-overturning ability of different substructures, the key design points are put foreword to provide some experience for the design.

Abstract: In order to research the most reasonable layers of reinforcement for stone arch bridge through section enlargement method, based on a bridge, on the premise of ensuring coordinated consolidation layer and original structural deformation, the finite element software is adopted to analyze the stress state of old and new concrete with different thickness of reinforcement for arch ring with the detailed exploration and structure evaluation data. Through consolidate the optimal reinforcement layer, in order to maximize the whole bridge bearing capability, then each section mechanical performance is improved, achieving ideal reinforcement, the conclusion can be used to reference for similar reinforcement design and construction, reducing workload of trial and calculation to increase the cross section technology.

Abstract: The main bridge of Quanzhou Bay Sea-Crossing Bridge is a composite girder cable-stayed bridge with span arrangement (70+130+400+130+70) m and with double pylongs,separated decks.It’s the first time to using the dry joints assembly in composite girder cable-stayed bridge,the technology of precasting and installing for integral segment is introduced.

Abstract: The reasons that the differences in temperature distributing and thermal stresses are produced in water conveying Box Bridge under solar radiation are analyzed in this paper. By FEM software ANSYS, temperature field and thermal stresses are simulated. Results indicate that temperature distribution in water-conveying concrete box bridge due to solar radiation is very complex. Temperature changes in the top plate are the most severe, followed by web-plate, with the bottom slab minimum. The actual temperature distribution can be approximately considered as conic curve. Under solar radiation considerable thermal stresses are produced in concrete box bridge both along the longitudinal and transverse direction and their value exceed tensile strength of the concrete. Therefore, thermal stresses under solar radiation must be considered in the design of water-conveying box bridge and temperature reinforcing bars should be appropriately added to the structure.

Abstract: Based on introducing engineering background and characteristics of river, the Yellow River in lanzhou section of the hydrological and sediment characteristics and characteristics of riverbed evolution are analyzed. On this basis, determine the once-in-a-century flow, and calculate the once-in-a-century flow when the bridge was analyzed and local scour of general erosion depth, scope of backwater height, etc.On the bridge of the embedment depth, clearance under the bridge, such as the check, and the bridge construction impact on the stability of river regime is analyzed.

Abstract: Based on the energy method and beam-element theory, the nonlinear strain are considered, non-stress length and non-stress curvature of element of geometry control method are introducted in the integration process of stain energy. The static equilibrium equation of the geometry control method is established. Take the impacts of structural geometric profile induced by temporary loads and temperature field during the construction procedure are investigated, the correctness of the geometry control method is verified by the numerical simulation analysis.

Abstract: Long-span suspension bridges are usually affected by the ambient temperature and the moving load during the service life. The concrete tower has lots of visible cracks and other diseases. In this paper, Fengdu Yangtze River Highway Bridge with main span of 450m was taken for example. Based on the thermal structure coupling analysis for the main tower, the elastic damage model for concrete was introduced. The bridge damage field was calculated under different temperature load conditions, which illustrated the reasons of cracks objectively and effectively. The results can provide reference for the future analysis on crack propagation behavior of concrete structure under the temperature effects.

Abstract: Structures are designed based on the seismic precautionary intensity, which is regulated by the government for each county. The basic target is to avoid the structure collapse under rare expected earthquake by the method of FEA and kinds of seismic measures, but buildings may encounter the seismic action with much higher intensity, the structural performance in this situation is researched by numerical methods in this paper. By controlling the parameters of displacement angle, axial compression and so on, the results show that the buildings may possess greater potential than expected.

Abstract: A mall large roof rack has been used 17 years. Because of upgrade, addition of decorate load, and missing the original design drawings, the spatial site test and check calculation of bearing capacity will have to be done. Using some detection tools, we can get arrangement, size, displacement, deformation, etc. And we can sue 3d3s software of Tongji University to check the calculation of bearing capacity. Through calculation and analysis, put forward to the original network frame the whole pre-stressing reinforcement and part of steel reinforcement bar outsourcing way, satisfying the requirements of design and specification, and to avoid the welding process, shorten the construction period, and achieved good social benefits.