This project belongs to other technical fields. For long-span bridges, based on function and economy, adopting a dual-use integrated double-deck bridge for public and rail purposes is a relatively economical and reasonable solution. Since urban rail transit is different from the "heavy load and high speed" of ordinary railways, but has the characteristics of "light load, low speed, and customized vehicles," existing technical standards cannot be fully adapted. Therefore, relying on the Minpu Second Bridge Project, the key technologies for building a long-span dual-use double-deck bridge for public and rail have been studied, providing a theoretical and technical foundation for the promotion and application of similar bridges in the future. Key innovations include:
(1) Innovative application of all-welded steel plate truss composite beams in double-deck bridges for both public and rail purposes. Research and launch a new type of all-welded steel plate truss composite beam structure, its main performance characteristics are: ① box members, ② large pitch spacing, ③ integral nodes, and ④ all-welded structure. Based on the structural characteristics of the overall welded joint, the laws of structural performance are established through 1:3 scale model tests and theoretical analysis, which is of great significance to structural design, manufacturing assembly and welding control. For the first time, the thermo-elastic-plastic finite element method was used to discuss the welding deformation and residual stress of common penetration welding during the processing of integral welded joints, and the elastic plate element finite element method based on inherent strain was used to predict the welding deformation of local and integral models of joint processing., filling the gap in domestic research. A total of 6 papers have been published on this application technology and 1 patent has been authorized.
(2) Innovative application of ballastless track bed on steel-concrete composite track deck. According to the characteristics of urban rail transit operation and track, combined with the characteristics of integral orthotropic steel bridge slabs, the steel-concrete composite track deck ballastless track bed is applied to reduce dead weight and improve structural performance compared with traditional track beds. 1 patent is authorized for this technology.
(3) Create a method for analyzing and determining the vehicle-bridge coupled vibration of a double-deck cable-stayed bridge for both highway-rail purposes. According to the service load characteristics of double-deck bridges for both highway and rail purposes, a three-dimensional refined vehicle-bridge coupling dynamic simulation analysis method for studying double-deck bridges is established. On the premise of meeting the accuracy requirements for overall dynamic performance analysis, good calculation efficiency and calculation accuracy are achieved. Using this method, on the basis of studying and comparing the technical standards of highway and railway bridges, the dynamic response of the bridge under highway and track loads is analyzed through three-dimensional dynamic simulation, and a reasonable stiffness index of the bridge is established, which provides a theoretical basis for the design of double-deck bridges. Published 2 papers.
(4) The first double-deck bridge structure with single column and high pier. In response to the limitations of urban bridge construction conditions, in order to reduce the amount of demolition and meet the organization of ground transportation, a new type of "stem"-shaped single-pillar pier was adopted. The shape is simple and the layout is compact, with little impact on the surrounding environment. Through the seismic test of a scaled model shaking table, the seismic response laws and seismic performance of a single column and high pier of a typical double-deck bridge are studied. On this basis, a conceptual seismic design method for a typical double-deck bridge is established, which is of great significance to the theoretical analysis method and design countermeasures of a double-deck bridge.
(5) Establish health monitoring system technology for dual-use double-deck bridges for public and rail purposes. Aiming at the performance of dual-use double-deck bridges for public and rail purposes, a set of suitable health monitoring systems during the bridge's service period is established to monitor the responses of various key performances (stress, deformation and vibration) of the bridge during the operation period in real time. It is of great significance to study the structural performance laws of this type of bridge.
This project has obtained 2 authorized patents and published 10 papers. The research results have generally reached the international advanced level (attached novelty search report and acceptance opinions). The research results have been successfully applied to the Minpu Second Bridge in Shanghai and the Liangjiang Bridge in Chongqing. The new output value was 34.314 million yuan, saving 101.7 million yuan in national investment, and published the monograph "Minpu Second Bridge-Double-Layer Fully Welded Steel Truss Beam Single Tower Cable-Stayed Bridge for Highway and Rail Transit." This achievement has far-reaching impact and significance on the construction of similar types of bridges in my country in the future.