Applied Mechanics and Materials Vols. 361-363

Abstract: In this paper, it is on the basis of gaining the main influence factors of strengthening economy for in-service bridge, using recursive hierarchical structure of analytic hierarchy process, constructing the assessment models about strengthening economy for in-service bridge in bottom, middle and top levels, combining with weight modify technology and fuzzy mathematics theory, the assessment results strengthening economic state is gained finally. By practical test, it can discriminant bridge using actuality effectively, and it has been a good guide to maintain in-service bridges safely, effectively and reasonably for maintenance administrative departments, and save a great deal fund for bridge construction cause.

Abstract: For solving the big deflection problem which is cause by the far cantilever segment of dead load zero bending moment method, analyzing the composition process of dead load and prestress bending moment, and this paper presents the improvement of dead load zero bending moment method.The improved method adopts the prestress in principle: far segment more and close segment litter, which not only can insure the prestress bending moment bigger than dead load zero bending moment in all over the cantilever constructing stage, but also can control the deflection well. The improved method is applied to a PC continuous bridge which has a main span of 168 metres, the deflection decreases 37.4% to that of the original design.

Abstract: In this paper a “bridge management intelligence decision support system” (BMIDSS) will be introduced. This system is based on the theory of decision support, considering the need of bridge manager and decision maker, utilizing database, model base, graphics base, knowledge base, and inference engine to realize date management, damage identification, status evaluation, fault diagnosis, remedy guidance to existing bridge.

Abstract: Three-dimensional finite element model of Yingwuzhou Yangtze river bridge was established by using the finite element software ANSYS. Since the characteristics of bridge fire differed much from that of buildings, Heating curve HC_inc was selected as heating curve caused by tanker fire. Heat loading was imposed on the middle of main span where the tanker fire had taken place of three-tower and four-span suspension bridge . The temperature field and stress, modulus of elasticity, strength of sling changing with time caused by tanker burning in midspan were systematically investigated to obtain the failure time of the sling. The calculation also compared the above results of HC_inc curve with that of ISO834 curve. This research can provide some references to fire risk prevention measures of bridge during its service life.

Abstract: Numerical simulation model to analyze the coupling vibration between vehicle and bridge established in this paper, upon the engineering background of Jinsha River Bridge. The finite element commercial software, ANSYS, is employed to set up the dynamic analysis model and to compute its natural vibration characteristics. Then CRH3 special refined model is built with SIMPACK, a multi-body dynamics commercial software. Considering the factors like track-rail irregularity, the dynamic performance of bridge and driving comfort level are obtained. The analysis results of coupled vibration demonstrate that bridge bears sufficient stiffness due to its satisfying vibration performance; the safety in operation of vehicle meets the requirement with the comfort index of "good". All the results not only provide reference for design, but also work as the theoretical basis for future design of similar bridges. The paper is deemed a s evidence of the priority of bridge-vehicle model by finite element method and multi-body dynamics method. The process of modeling turns to be stylized, which avoids the unnecessary programming for individual project.

Abstract: Yongjiang railway extra long-span cable-stayed bridge uses the orthotropic deck of steel box girder, and it is the first time that box girder used in the railway cable-stayed bridge, so it is necessary to do a research on the mechanics behavior of this structure with fatigue model test. The accuracy of the fatigue model test data results in the rationality of the test scheme, and the research contents of the test scheme are as follows: the finite element model of steel box girder has been built to analysis the characteristics of the stress distribution, and the fatigue-sensitive regions have been determined; three model schemes have been designed and compared under the principles of stress equivalence and economical efficiency , and the third model has been used as the final fatigue test model . The research result can provide reference for the design of fatigue test model scheme of the same kind of bridge.

Abstract: In recent years, with the rapid urbanization process and increased accidents of bridge damage and collapse, the research of bridge health monitoring and early-warning technology for the public safety has been promoted. Temperature load is one of the main loads to incur the deformation and the variation of stress of bridges. So temperature measurement is an important component of health monitoring for urban bridges. In this paper, a smart temperature measurement system is described which takes advantage of FBG sensor performance characteristics to improve the bridge temperature measurement. At present, the system has been integrated and applied in the project of main roads bridge Online Safety Monitoring Management System in Hangzhou (Phase II), a web-based urban bridge cluster monitoring system have been established since 2007. According to a tied arch bridge case studies, the one-year measurement data shows that the system not only can accurately collect the bridge temperature information and variety, but also successfully improve the performance benefits such as reduced measurement uncertainty, increased robustness, and failure prediction and detection.

Abstract: Crossing Anchang River in Mianyang City，Anchang Landscape Footbridge connects Yuyingba and Baisheng Plaza. It bears large amount of pedestrian loads. The approximately anti-symmetric structure of this prestressed concrete bridge is girder-arch combined with unique and elegant appearance. However, without much design and construction reference, loading test is necessary for this footbridge to ensure its security in the future. Tanks are adopted in static test as the equivalent pedestrian loads to imitate the actual working conditions of the bridge and to assess its working capacity and construction quality, providing basis for the completion and the design exploration. Test methods and analysis results of this footbridge can be used as reference in loading test and dynamic performance analysis of similar bridges in the future.

Abstract: Fiber-reinforced concrete is well known for crack control by bridging cracks in the concrete. Short, discontinuous fibers are added into plain concrete to provide post-cracking ductility to the fiber-reinforced concrete. Although fiber-reinforced concrete has been used in various civil engineering applications, the practical application of fiber-reinforced concrete in bridge approach slabs is rarely found. In this paper, steel fibers, serving as macro-fibers, and polyvinyl alcohol fibers, serving as micro-fibers, were added to the approach slab concrete for crack control purpose. This paper describes flexural tests of four fiber-reinforced concrete beams and loading test of a full scale fiber-reinforced concrete approach slab. Results from the flexural beam test show that the addition of fibers greatly improves the fracture toughness of the concrete. Results from the loading test show that the overall performance of the slab is comparable to conventional reinforced concrete approach slabs, and the surface cracks on the slab due to negative moment can be adequately controlled by the addition of steel and polyvinyl alcohol fibers into concrete, even without top reinforcement mat.

Abstract: The vehicle and TMD were modeled as a combination of several rigid bodies, which were connected together by a series of springs and dampers, the bridge was modeled by beam elements, and thus the spatial vibration equation of the system of TMD, vehicle and bridge was established, which was solved by direct integral method. A highway and railway bi-purpose cable-stayed bridge was taken as an example, the spatial vibration responses were calculated when the train and car run through the bridge, and the influence of TMD on the vibration response was discussed. The results show that the bridge has the sufficient lateral and vertical stiffness, the train and car affect each other when they cross the bridge at the same time, and TMD can play a good role in controlling the vibration response of long span cable-stayed bridge-train-car coupling system.