Advanced Materials Research Vols. 446-449

Abstract: In order to research the weathering characteristics of Tertiary silty Mudstone along Chengnan Freeway, the experiment of the engineering characteristics, the weathering durability, the weathering speed to be done for the different weathering degree silty mudstone. The test result show that when the weathering degree of the rock mass deepen, the content of clay minerals in the rock mass is increase, the activity chemical composition in the rock mass is decrease relatively, the dry density of the silty mudstone is decrease, the total porosity and the water absorption of the silty mudstone is increase, the mechanical properties is weak, the rock mass is soften and collapse easily. The weathering speed of the rock mass with the relevant to the weathering degree and the exposed area of the rock mass.

Abstract: In order to research the different types of isolation bearings impact on bridge performance, parameters of lead rubber bearing, super high damping rubber bearing and friction pendulum bearing are designed for the three-span continuous bridge. With the method of nonlinear time-history analysis, dynamic characteristic of this isolated bridge is studied by using sap2000. Analysis results show that the isolated bridge with three types isolation bearings has a good seismic isolation effect under rare earthquake. The difference of shear force between friction pendulum and other two types is about 4% below.

Abstract: The Taizhou Yangtze river bridge is a suspension bridge with three pylons and two 1080m long navigation spans. The middle pylon with height 191.5m is made of steel. The general construction procedure of the middle steel pylon is briefly introduced. Construction control of the pylon is carried out during the whole process of the construction. The control concept is extended to the manufacture stage besides the installation stage. The manufacturing alignment errors are strictly controlled in precast process of the segments in factory, and the alignment error is identified and predicted precisely during the installation stage. The adjusting joints are adopted to adjust the accumulated errors, which ensure that the steel pylon alignment could satisfy the as-built precision requirements.

Abstract: In this paper vehicle-bridge coupling system is divided into vehicle system and bridge system. The equations of vehicle vibration and bridge vibration are solved in numerical method, considered the displacement of wheel and rail as convergence criterion. The security of running train is studied on the hand of wheel-rail force, derailment coefficient, load decrement rate of wheel weight, and the reason of train derailing on high-speed railway bridge is analyzed. By the example of multiple span simple supported beam bridge, the result derived by this method is proved that the bridge meet train security and amenity requirement.

Abstract: The anchorage zone of pylon is the key part of the cable-stayed bridge, and it is also the difficult and important part in designing and construction of cable-stayed bridge. Especially for an abnormally shaped anchorage zone, it is hard to analyze the actual stress distribution on the bridge pylon by a simple mechanical method. The full scale segment model test of the abnormally anchorage zone of Maling River cable-stayed bridge pylon was described. In the test, the cracks, stress and deformation were observed and analyzed. Further more, the finite element analysis for the segment model was carried out. Through the contrast analysis between the model test and the finite element analysis, some important conclusions are drawn such as the model test and the finite element analysis have a good agreement, “the joints outside” and “the polyline inside” are the easy cracking zones, the cracking resistance coefficient of the model is no less than 1.3 and the destroy safety coefficient is no less than 1.6, which can provide important theoretical basis for the design and construction.

Abstract: The α-type high-strength gypsum with its superior strength and performance is widely used in precision casting, ceramic molds, arts and crafts as well as plaster and GRG self-leveling and other industries that have higher demands to the dimensional stability of the products. Solidification rate of expansion is an important characterized parameters of gypsum volume stability, and also an important indicator of α-High-Strength gypsum plaster. The common adjustment method of Solidification rate of expansion is to add additives to change the gypsum hydration process. But the influences of different types of additives on setting expansion have not been studied yet, therefore, this paper studied on the influences of citric acid, tartaric acid and sodium pyrophosphate on the solidification rate of expansion of the α-High-Strength gypsum plaster. The results indicate that the gypsum expansion rate was decreased with the increase of gypsum set retarder, the expansion rate was firstly increased and then decreased when the citric acid and sodium pyrophosphate increased; however, when the tartaric acid increased, the expansion gradually decreased, and the tartaric acid and the expansion of the gypsum by and large are in an inverse proportion.

Abstract: Different from traditional strengthening methods, the technology on replacement of structural members is a new strengthening concept for solving the problem of local failures in prestressed concrete cable-stayed bridges. To clarify the characteristics and realization ways of this technology, practical experience and latest achievements of strengthening prestressed concrete cable-stayed bridges in recent years in China were summarized comprehensively, such as replacement of stay cables, replacement of closure segment, replacement of tension rocker bearing cables at subsidiary piers, et al. Forms of Special diseases were described, and their failure mechanisms were given. Then calculation methods and key techniques of these strengthening ways were introduced. Engineering application and practice showed, the technology on replacement of structural members is a system engineering, namely, not only new structural members should meet the mechanical requirements of their own, but also the structural condition of whole bridge should be improved through replacing structural members. Establishment and development of this technology had important and far-reaching significance to promote the technical level of strengthening long-span bridges under the condition of special diseases and ensure bridges in the sate of safe and sustainable operation.

Abstract: Increased traffic volume has made it urgent to improve highway capacities by widening the existing embankments in south-eastern coastal areas of China. Adding a new embankment adjacent to the existing embankment will result in additional settlement within the existing embankment. And also, differential settlement will occur between the existing and widened embankment over soft soils. Excessive settlement and/or excessive differential settlement may cause longitudinal cracks, drop-off on the road surface, even local or global instability. A numerical analysis was conducted to investigate the influence of the thickness of soft soils on the development of settlements of the existing and widened embankment. The effect of widening time on the settlements was also discussed. The results indicate that the thicker the soft soils, the more time needed for the existing embankment to reach its final settlements. It is also found that there exists a most appropriate widening time for minimizing the additional settlements of the existing embankment on soft soils with a given thickness.

Abstract: This paper introduces the main dimensions and drawings, and discusses the static analytical results of a prestressed concrete bridge with slant-legged rigid frame. The numerical mode of this bridge was built by the specialist FEM software. The results show that the central span of box-beam and the slant-legs forms an arch-like structure which brings these members into compressive-bending states, the side span of box-beam is in bending. For the box-beam, the internal forces mainly come from the dead load, the prestress effects and the vehicle load. The sedimentation of supports and the entire warming or cooling have certain influence on the side span box-beam and the slant-legs. Decreasing the shrinkage and creep of concrete is also important for this bridge.

Abstract: The Fu River bridge in Hechuan district is located in Chongqing where the summer temperatures could be overed 40°C. It is necessary to analyze the temperature to reduce the impact of high temperature to the line shape. The impact of temperature on the line shape was described in this paper. Based on the analysis of monitoring results and Newton method of interpolation, the change rate of cantilever elevation and the temperature influence law were shown. And the control measures were also proposed. Finally achieved the design requirements of the line shape of bridge and construction monitoring.