Applied Mechanics and Materials Vols. 501-504

Abstract: Vertical prestressing tendons finishing twisted steel is widely used in the concrete box girder, but ,it is hard to effectively control the loss of anchor stress. Based on the dynamic, the three-parameter model was built which include the frequency of the exposed segmentthe segment length of the exposed steel reinforcements and effective tensile force. The vertical tensioning force of the box girder webs model was designed at laboratory .The natural frequency was obtained through test. Relying on experimental test data ,the model of the nonlinear relationship between fine bundle the rebar tensile force and the exposed segment frequency was established. Here in NDT methods to be able to quickly and effectively measured vertical prestressing tension.

Abstract: With a double-beam calculation model, the study on dynamic characteristics of the cable-stayed bridge with one tower was carried out. Modal analysis and space nonlinear time history analysis were adopted.The latter used EI-Centro earthquake wave, it acted on the structure from three different direction:transverse, longitudinal and vertical respectively. From these analysis, dynamic characteristics of the bridge are acquired, internal force and displacement in critical position of the beam and tower are given too. At the same time, wind-resistant stability of the bridge is also calculated through a experienced formula. All the results provide important reference for design and construction.

Abstract: An on-site static load test of a reinforced concrete double-arch bridge with fracture is carried out, and a comparative analysis of the measured experimental results of the bridge working conditions and the calculation results of Midas/civil Finite Element Model is performed. The results show that the performance and structural deformation recoverability of the bridge is weak. The bridges overall load-bearing capacity does not satisfy its designed requirements.

Abstract: There are many old damaged double-curved arch bridges with design drawing lost serviced for more than 40 years are still used in West China. Based on the repair and improving the carrying capacity work of a damaged badly double-curved arch bridge whose design drawing is lost with main span of 41.0m constructed in 1962 in Sichuan province of China, health inspecting and safety assessment for this type bridge using non-destructive methods is studied. Then the strengthening design of filling concrete and enlarging the section method is proposed. High performance self-dense slight-expansion concrete and embedded bar techniques are applied in strengthening construction. After the strengthening work completed, the arch bridge is still in very good work condition experienced two devastating disasters of the 2008 Sichuan Wenchuan and the 2013 Sichuan Lushan earthquake, with the distance of bridge site to epicenter less than 100km, which proved the safety assessment and the strengthening design proposal are effective and feasible.

Abstract: this article through the detection of T-shaped girder bridge, grasp the present situation of bridge structure and disease, and evaluate existing technical conditions to provide technical basis for the repair and reinforcement of the bridge in the future.

Abstract: Influence analysis of train speed on vibration responses of footbridge entrance to platform induced by wind pressure due to main line train have been researched in the paper. With some footbridge as the research background, different wind pressure produced by different train speed acting on the bridge surface simulated by CFD method has been adopted to the bridge, thus influence of train speed on vibration responses of footbridge induced by wind due to main line train are obtained. Simulating results show that the vibration responses of footbridge entrance to platform intense with the increase of train speed.

Abstract: Safety inspection of the bridge has become particularly important owing to a large number of aging bridges in China, in order to evaluate the safety of a bridge project that has been completed in Harbin, research methods of combining theoretical analysis, numerical simulation and field test is applied, response parameters changes under static and dynamic loads is studied emphatically in this paper.

Abstract: When the scaffold construction method is applied on long-span steel trussed arch bridges, reasonable setting of the temporary pier elevation has significant influence on assembly linearis and safety assembly of long-span steel trussed arch bridges with semi-cantilever. In this paper, in accordance with the manufacturing linearis steel trussed beam bridge and steel truss beam linearis changing during building process, the calculation of temporary pier elevation was studied systematically, and practical function was deduced. Then, the method was applied to a long-span steel trussed arch bridge. The obtained result by in-situ assembly and dismantling presents that: 50 mm preserved method is considered in this paper, which can provide convenience for removing the temporary pier. At the same time, the rationality and reliability of the presented approach are verified. It also can provide reference for similar bridge construction.

Abstract: When the cantilever construction is adopted by the prestressed concrete continuous girder bridge, the order of two key procedures between removing temporary support and tensing remanent prestressed cable is used to be ignored. In order to study the influence of procedure inversion, the influences on bridge shape, stress distribution and prestressing loss were calculated for one common prestressed continuous concrete box girder bridge by MIDAS CIVIL 2006, respectively. The obtained result presents that: the influence on the bridge shape and the prestressing loss are not apparent, but the influence on the stress distribution is serious; the maximal compressive stress of procedure inversion is more 42.3% than common construction procedure only by tensing the remaining steel beams at box girder; especially, the combining area between the box girder and temporary support is easy to pull out. So, the procedure inversion construction method cant be accepted.

Abstract: Due to vehicle load, shrinkage, creep, temperature and other factors, the strength and stiffness degenerate increasingly for the pre-stressed concrete continuous beam bridge in service. The problem, such as cracking, excessive deflection in the mid-span caused by the deterioration of the elastic modulus and pre-stress, has a direct impact on the usability, durability and security. To solve the problem mentioned above, according to the monitored deflection of the bridge in service at different time, the elastic modulus and the effective pre-stress are evaluated by establishing the inversion analysis model based on the inversion theory.