Advanced Materials Research Vols. 671-674

Abstract: For better combining the uses of combat readiness equipments in war and in peace, taking the design of an extra-long railway overpass bridge’s construction supporting frame for example, this paper probes into the application method of the combat readiness equipments used in bridge construction.

Abstract: This paper studies the evaluation of the proper stress intensity factor ranges in the fracture mechanics-based fatigue analysis of the rib-to-deck welded joints of orthotropic steel decks. It is pointed out in the paper that the stress intensity factor ranges used in Paris law for the fatigue crack growth at a rib-to-deck welded joint can not be taken as a value proportional to the corresponding stress ranges since the compressive stresses are the dominant transverse stresses in the cyclic stresses under the action of truck traffics. The proper fatigue design loads to characterize the standard truck loading for the accurate calculation of the tensile transverse stresses at the rib-to-deck joints is also discussed in the paper. It is shown that the loads from two neighboring wheel-axles of heavy trucks have to be taken into account.

Abstract: For steel box girder of cable-stayed bridge, which using incremental launching method, during the launching process, structural system and boundary conditions were changing, structure mechanical behaviors were complex. It was necessary to conduct a comprehensive analysis on internal force and deformation of the whole structure during the launching process. Took a cable-stayed bridge with single tower, double cable planes and steel box girder in China as an example; finite element software MIDAS Civil 2010 was used to establish a model for steel box girder, simulation analysis of the entire incremental launching process was carried out. Variation rules and envelopes of the internal force, stress, deformation and support reaction were obtained. The result showed that: the maximum value of positive bending moment after launching complete was 60% of the maximum value of positive bending moment during the launching process. The maximum value of negative bending moment after launching complete was 78% of the maximum value of negative bending moment during the launching process.

Abstract: In order to determine every rational construction state and obtain perfect finished dead state of the cable-stayed bridge, a quadratic programming model for optimizing cable tension was put forward. The adjustment of multi-object control parameters was achieved by using the weighting coefficient in the optimization model. In the optimization calculation of a cable-stayed bridge, the forward-calculating method was used and the results show that mechanics concept of this method is definite, the rate of convergence is fast and some disadvantages of other methods are avoided.

Abstract: The shear lag and shear deformation effects on deflection of composite girder with corrugated steel webs (CGCSW) was studied. The influence of shear lag and shear deformation effect was expressed by deflection coefficient δ1 and δ2. Parametric analysis within a scope of dimensions of built-in girders was performed, including girder span, width, height, thickness of concrete flange and thickness of steel web. The results show that the deflection coefficient of shear lag effect is approximately directly proportional to square of width-span ratio, while the deflection coefficient of shear deformation effect is related to all parameters. It’s suggested that shear lag effect on CGCSW’s deflection be neglected when width-span ratio is smaller than 1/9, and shear deformation effect should always be considered.

Abstract: Bridge jacking technology is a new technology in the field of old bridge reconstruction. Based on the case of Beijiang River Bridge jacking of Fokai highway extension engineering, the paper designs steel hoop as jacking force platform. By using ANSYS software, it makes finite element analysis and calculation as well as compares with the experimental data to check the reliability of models. In addition, the paper puts forward the optimization methods of steel hoop based on the analysis of the results. At last, it achieves the objective of saving materials and simplifying installation and use as well as provides guidance for the similar engineering.

Abstract: Parametric design language in finite element analysis software ANSYS is adopted to establish the analysis model in the construction of the 0# block of a rigid frame bridge on the pier bracket in different times, simulating the placing process of the 0# block of this bridge with three times, and analyzing and understanding the deformation and stress distribution of the bracket and 0# block during each placement of the 0# block. The load participation coefficient of the concrete placed in the 0# block in subsequent 0# block construction is obtained by the analysis and comparison of the stresses of the bracket’s longitudinal beam in the 0# block placed in one time and the 0# block placed in different times. In the meantime, the numerical calculation is proved to be reliable and correct based on the calculation of multiple software programs and the comparison of field test data. These conclusions are meaningful for the design of the bracket for multiple mass 0# block placements, load calculation, and 0# block construction monitoring.

Abstract: To study the static and dynamic performance of large-span steel trestle, the steel trestle space finite element model was established with the consideration of the element coupling. The normal stress distribution of trestle bars under the static action was calculated.Combined with subspace iteration method and the time- history analysis, the trestle vibration modal and the dynamic stress extreme value of main bars were analyzed. The structure is more sensitive to transverse earthquake, and under the existing conditions the bar stresses are controlled in allowable range, the structure is safe and reliable.

Abstract: Taking Wei River Bridge with span combination of 69m+7×90m for example, the method of determining the steel-concrete joint section for variable cross-section steel-concrete hybrid continuous box girder bridge were investigated by finite element and parameter sensitivity analysis. The results show that it was an effective method for hybrid girder highway beam bridge from the view of mechanical property that the bending moment under dead load combination was employed as the main parameters, considering the negative bending moment in the pier top and the amplitude of bending moment in the joint section under live load. But based on reasonable structure stress conditions, the length of steel box girder that the host material of the bridge was concrete could determined by economy principle.

Abstract: Due to the environment, climate, loads and other factors, the pre-stress applied to the beam is not a constant. It is important for engineers to track the state of the pre-stress in order to ensure security of the bridge in service. To solve the problem mentioned above, the paper puts forward a new way to analyze the effective pre-stress using the displacement inversion method based on the inversion theory according to the measured vertical deflection of the bridge in service at different time. The method is a feasible way to predict the effective pre-stress of the bridge in service. Lastly, taking the pre-stressed concrete continuous rigid frame bridge for example, the effective pre-stress is analyzed by establishing the finite element model.