Abstract:This paper reveals the corresponding relationship between the geometric shape of the cable and the bending moment diagram of the simply supported beam under the vertical load of the suspension bridge cable, which can be called the bending moment diagram theory in terms of the elastic theory, deflection theory and finite displacement theory of the suspension bridge structure analysis and calculation. Because the bending moment diagram of simply supported beam is convenient, intuitive and clear in concept, it can greatly simplify the structural analysis and calculation of suspension bridge, and is an accurate analytical solution. The cable shape calculation software of suspension bridge is compiled according to the bending moment diagram theory, which can calculate the empty cable shape and the completed bridge shape under the action of suspender force, and introduces the software function and use method.

Abstract:Fatigue damage of bridge cables is one of the main reasons for safety accidents of bridges in use. The cable fatigue test can obtain the fatigue life parameters of the finished cable, which is of great significance to estimate the service life of the bridge and improve the design scheme of the finished cable. The fatigue test cycle is long, the information obtained by manual inspection test process is limited, and the number of load cycles during fatigue failure cannot be determined. The sound pressure signal in the test is recorded with a recording pen, and the kurtosis analysis method is introduced into the sound feature extraction of fatigue failure to accurately determine the time of fatigue failure, which enriches the significance of cable fatigue test. The practical application shows that the proposed method is effective.

Abstract:The low-pylon cable-stayed bridge is mainly constructed by the cable-stayed cables bearing the tension at both ends. This paper takes the prestressed concrete low-pylon cable-stayed bridge with double towers and single cable plane of Beijing-Hangzhou Bridge as the engineering background. From the construction technology of the main bridge, this paper briefly describes the construction process of the main bridge of the low-pylon cable-stayed bridge, and introduces in detail the key construction steps in the construction process of the main bridge. This paper focuses on the concrete construction process and key construction technology of the cable-stayed cable of the main tower, finally discusses the construction characteristics of the main bridge of the low-tower cable-stayed bridge and the advantages of the construction technology of the cable-stayed cable, and draws the conclusion that this technology can be popularized and applied, which provides reference and experience for the construction of the same type of bridge in the future.

Abstract:Tie arch bridges were built in large numbers in China in the 1990s, and many of them have to be replaced due to serious corrosion of the ties. Ful River Bridge in Mianyang City is a (46+202+46)m swallow type bollard arch bridge, the length of the bollard anchorage section is long and the bollard cannot be replaced directly. Taking the bollard replacement project of this bridge as an example, the key technologies of structural system conversion, temporary bollard and temporary support system setting of bollard replacement project were studied, and the construction points of bollard replacement project were introduced for the reference of similar bridge projects for reinforcement and maintenance.

Abstract:Post-tensioned prestressed hollow core slab is a common form of superstructure in bridge engineering. In this paper, the theoretical analysis of anchor stress in post-tensioned prestressed concrete hollow core slabs was carried out, and the effects of setting of reinforcement bars and thickness of web on anchor stress were discussed; the strain under anchor of hollow core slabs under the tension of steel beam was tested, and the cracks under anchor concrete were observed to analyze the mechanism of cracks under anchor. The study showed that: increasing the reinforcement rate of under-anchor reinforcement and thickening the web can reduce the under-anchor concrete tensile stress, and the effect of thickening the web is more significant; excessive local stress in the under-anchor concrete leads to local cracks and structural damage, and the cracks do not necessarily appear on the concrete surface immediately when the prestressing beam is tensioned, but appear after the stress redistribution in the under-anchor concrete.

Abstract:Current evaluation methods for bridge technical condition often fail to reflect the fuzziness and stochasticity during the evaluation process, so the Cloud Barycenter Theory and the deterioration model are introduced to conquer the shortcomings. The cloud models of every hierarchy and every member are built respectively based on the Cloud Partition Method, and the bridge technical condition are divided into five clouds. The evaluation method based on the Cloud Barycenter Theory is developed and the deterioration model of bridge technical condition is obtained. Detailed technical condition evaluation is conducted on the Nanning Bridge by the proposed evaluation methods based on Cloud Barycenter Theory and current standards, respectively. The study results show that the final condition grade evaluated by the proposed method by this thesis agrees well with the method provided in current standards. However, the biggest difference is that the model built herein gives consideration to the fuzziness and randomness during the evaluation process, which shows high reliability and wide applicability of the proposed bridge technical condition assessment method.