Abstract:With the increasing demand for global connectivity, research on superlong-span bridges has received increasing attention. This study revealed that the absence of internal forces and infinite structural stiffness are the basic conditions for building bridges with infinite spans. Based on this, three types of superlong-span collaborative bridge systems were built using the bridge type quadrant diagram and the characteristics of superlong-span bridges and specific measures to improve bridge stiffness were summarized. The bridge type quadrant diagram provides not only a simple approach for building structurally complex collaborative bridge systems but also a method for building superlong-span bridges. The results show the existence of three collaborative system bridges: the stayed cable-umbrella truss collaborative system bridge, the suspension-arch collaborative system bridge, and the stayed cable-suspension-arch-umbrella truss collaborative system bridge. Those collaborative system bridges meet the conditions of relatively ideal bridges and have the potential to become superlong-span bridges. The symmetry and force transmission paths of the bridge quadrant diagram reveal the construction characteristics of superlong-span bridges.

Abstract:To study the influence of viscous damper parameters on the mechanical behavior of long-span railway suspension bridges, a railway suspension bridge with a main span of 1,100 m and asymmetric towers was used as a case study. Using dynamic time-history analysis methods, different damping coefficients and velocity exponents were analyzed for their effects on the dynamic response of the bridge under both train crossing and E2 seismic conditions. The dynamic response results were compared, and a mechanism analysis of the damper's effect on the structural response was conducted. The computational results indicate that, for the train crossing condition, increasing the damping coefficient and decreasing the velocity exponent can reduce the longitudinal displacement at the beam ends while increasing the bending moment at the base of the towers; for the E2 seismic condition, increasing the damping coefficient can reduce the longitudinal displacement at the beam ends and decrease the bending moment at the base of the towers, whereas the value of the velocity exponent has little effect on the structure; the parameters of the dampers should consider various dynamic conditions to ensure control objectives while also considering the energy dissipation capacity and constructability. Finally, parameter design recommendations for nonlinear viscous dampers are proposed.

Abstract:The continuous increase in the single-unit capacity of wind turbines and the continuous increase in the hub height have led to new requirements for the structural performance of wind turbine towers. Precast pre-stressed concrete towers that are widely used in the field for large turbines and high towers are gradually replacing traditional steel towers on the market. However, research on structural joints, especially vertical joints where several precast concrete pieces are assembled into a ring segment, is limited. One way to improve the integrity of the structure and clarify the load path is to apply circumferential prestressing to the annular precast tower containing vertical structural joints. With the structural design example in a certain concrete wind tower project, this paper analyzes the effects of different magnitudes of circumferential prestressing on the structural performance under the service loads and the ultimate loads and proposes a method to determine the optimized design of the structure.

Abstract:Post-tensioned bonded prestressed concrete towers have gained wide recognition and application in the wind power industry because of their excellent integrity and high load-bearing capacity. During the design process, crack verification under normal service conditions is often a controlling factor in structure design, and this verification is closely related to the calculation of prestress losses. This paper, which combines Chinese and European codes, introduces in detail the calculation method for prestress loss in internally post-tensioned structures. Additionally, the differences in the calculation methods specified in the Chinese and European codes are compared and, considering the characteristics of wind turbine towers, methods and recommendations for selecting relevant parameters are provided, with the aim of serving as a reference for the design of similar structures.

Abstract:The main cable strands of self-anchored suspension bridges are typically anchored directly to the back of concrete or steel girders, a construction method that has durability issues. To address this problem, a new combined anchorage structure using finished cables and a connecting shaft is proposed. This anchorage structure is connected to the end of the main cable strands via the connecting shaft. This article provides a detailed description of the design concept and specifics of this new anchorage structure, including instal-lation methods and procedures for removal and reinstallation during bridge operation. Full-scale static load tests validated the feasibility of the proposed design. This new structure improves the durability of the main cable anchorage section, allows for its replaceability, and can be extended to other similar applica-tions, offering considerable reference value.

Abstract:The Yancheng "Green Energy Port" is an important project planned under the National Natural Gas Pro-duction, Supply, Storage, and Sales System Construction and Interconnectivity program, and it is also the largest liquefied natural gas (LNG) reserve base currently under construction in China. In the first phase of the "Green Energy Port" project, 10 large LNG storage tanks were built, including 4 tanks with a capacity of 220,000 m3 and 6 tanks with a capacity of 270,000 m3, the latter of which are currently the largest storage tanks with a single-tank capacity in the world. This report provides a brief introduction to the project context, outlines the layout of the prestressed system in the LNG storage tanks and the construction phases, and summarizes the critical tests for the prestress system in cryogenic tanks.

Abstract:The main bridge of the Hutuo River Bridge, a single-tower, single-pylon cable-stayed bridge, is inspired by "landscape painting", featuring a unique "scroll-shaped" tower with a spatially twisted cable arrangement. The bridge has a span arrangement of (40 + 150 + 150 + 40) meters and utilizes a fully floating system. The structural support system incorporates vertical seismic isolation bearings, longitudinal and transverse dampers, and transverse wind-resistant bearings. The tower’s cross-section transitions from oval at the base to circular at the top, with decorative scroll edges rotating counterclockwise at approximately 90° from the base to the top. The tower above the deck is steel, while the part below the deck is concrete, with a steel–concrete transition section near the deck level. The main girder uses a double-box steel structure with transverse beams. The stay cables are made of 1860 MPa-grade steel strands, with an anchorage spacing of 9.0 m along the cable-stayed beam. Unlike the traditional fan-shaped cable arrangement, this bridge adopts a reverse layout, with the outermost cable having the lowest anchorage point on the tower. The foundations for the bridge towers, auxiliary piers, and edge piers are all constructed using bored piles.