Abstract:Regarding the application of high-strength steel in bridges, this paper describes the development and changes in the properties of high-strength steel through a review of the relevant literature from the past five years. This paper introduces the research status of high-strength steel, steel strands and high-strength rebars and focuses on the research status and application level of HRB500 and HRB600 high-strength rebars, combined with their performance characteristics and application cases, and prospects for corresponding development and application in the future.

Abstract:To promote the development of collaborative system bridges, a bridge type quadrant diagram is utilized in this study to build and validate multiple existing collaborative system bridges. Through the bridge type quadrant diagram, various new types of collaborative system bridges with different structures are built. The research indicates that collaborative system bridges are complex structures based on five basic bridge types. Using the bridge type quadrant diagram, various structural types of collaborative system bridges can be arranged and combined. Considering the characteristics of collaborative system bridges, a specific collaborative system bridge scheme is proposed to address mid-span deflection issues in large-span beam bridges. The bridge type quadrant diagram can be used to develop a simple and efficient method for the design and research of collaborative system bridges in the future.

Abstract:Herein, a main girder structure for a cable-stayed bridge with concrete-filled steel tubes serving as the main longitudinal ribs is proposed. The feasibility of this structure is verified by calculation and analysis. Then, economic analysis of this structure compared with other types of cable-stayed bridges with main girder structures of the same kind of span is carried out. The results show that the structure is feasible and eco-nomical, and it has superior seismic performance, especially in high-intensity and complex mountainous terrain regions in western China.

Abstract:Cracking evaluation technology during construction is crucial for evaluating the safety performance of long-span bridges and for selecting remedial measures. In this paper, by focusing on the cracking of pier cap block 0 during the construction of a continuous rigid-frame bridge in Guizhou Province and combining this information with measured data, such as crack depth, length, and position, the effects of two extreme remedial measures—complete closure after cracking and nonclosure after cracking—on the structural performance of the entire bridge are analyzed using the finite element software Midas FEA and compared with the originally designed structure without cracking. The analysis results indicate that the structural performance of the completely closed structure after cracking is basically consistent with that of the originally designed undamaged structure. Nonclosure after cracking has a significant impact on the stress distributions of the top and bottom slabs and webs near pier cap block 0, and the stress levels of these components are greater than those of the undamaged model. In this study, the most unfavorable conditions are comprehensively considered, and the influences of bridge cracks during the construction stage on the structural performance of the entire bridge are investigated. This investigation plays an important role in the safety performance evaluation after cracking during the construction of bridges, and it can serve as a practical reference for these tasks.

Abstract:Based on the phase II project of Block 07, District 14 of Shanggang, Baoshan New City SB-A-4, Shanghai, the underground three-layer foundation pits were excavated to the basement at one time. Due to project needs, the backfill construction progress of specific super high-rise building areas needed to be excavated sig-nificantly in advance. The calculation method of an elastic ground slab combined with a space frame beam was used to establish an integrated coupling analysis model for the foundation pit and the main structure in the incomplete state and to calculate the interaction mechanism and load distribution between the foun-dation pit and the main structure under a specific state. Under the premise of non-zoned excavation of the foundation pit, the preliminary removal of the supports in the specific area and the backfill construction of the main structure were achieved. The actual measurement data verify that, as a type of strut structure with a large bearing capacity and high structural stiffness, a plate wall combined with prestressed steel diagonal braces can ensure that the plate wall has better lateral stiffness and overturning resistance through the application of matching prestresses. This meets the conditions of an interstage support replacement system for deep foundation pits. The successful implementation of the project provides certain reference value for deep foundation pits that need backfill construction in advance.

Abstract:The Yanluo Pedestrian Bridge has a length of 136.0 meters, a width of 11.5 meters, a main span of 108.0 meters, and a rise span ratio of 1/11.74. The bridge design introduces the innovative "Downward Through-pass Cable-stayed Inclined Arch Composite Structural System." Compared to conventional deck-type arch bridges, this composite structural system significantly enhances the load-bearing capacity of the main arch, reduces the horizontal forces on the arch abutments, and improves the stiffness of the main arch. The Yanluo Pedestrian Bridge consists of the main arch, main girder, bridge towers, main cables, back cables, vertical braces, steel pipe columns, and foundations. The construction employs minimal support in the water.

Abstract:This paper presents the design and construction process of a 148° swivel for a curved bridge with a radius of 60 meters. Due to the small radius of the curved bridge, there is a significant imbalance moment during swivel. Therefore, in the structural design, measures such as pier-beam connection, installation of high-strength prestressed anchor rods, pre-eccentricity setting for the swivel structure, and filling of iron sand concrete inside the box beam at the top of the pier are adopted to balance the moment. Both the curve radius and the swivel angle of the bridge set world records for bridge swivel construction.