Abstract:Taking the Wuhan Yangtze River Flood Control Model Test Hall as the engineering background, a new hybrid spatial structure system is proposed: arch supported prestressed grid structure. Combined with the characteristics of the structural system, from the angle of initial cable deformation, the stiffness method theory of the structure is established, and the mixed influence matrix method, cyclic iterative approximation method, "sequential analysis method" of initial cable deformation, and "sequential analysis and reverse Iterative method" of cable tension are proposed for the analysis of the whole process of prestress of the structure, which is not only applicable to arch supported prestressed grid structures, It is also applicable to other similar hybrid spatial structures. Finally, the accuracy and effectiveness of this method were verified through an actual calculation example of the Yangtze River Flood Control Model Test Hall project

Abstract:The cracking problem of concrete in the negative moment zone of steel box concrete composite continuous beams has affected the development of such composite structures towards larger spans. In response to this issue, a new technology of applying external cables in steel box concrete composite continuous beams is proposed, and the beneficial effect of applying external cables on enhancing the crack resistance of concrete in the negative bending moment zone of steel box concrete composite continuous beams is studied, improving the elastic-plastic structural performance of steel box concrete composite continuous beams. Through comparative experiments, it has been shown that after the application of external cables, the cracking load of concrete in the negative bending moment zone of the steel box concrete composite continuous beam increases by 2.8 times, the elastic-plastic bending stiffness of the composite continuous beam increases by 29.35%, the bearing capacity increases by 34.67%, and the structural performance is significantly improved. On the basis of experimental research, the relationship between the local mechanical properties in the negative moment zone of the steel box concrete composite continuous beam and the overall nonlinear structural performance is analyzed, revealing the mechanical essence of external cables improving the elastic-plastic structural performance of the steel box concrete composite continuous beam, and providing suggestions for bearing capacity calculation. The research results can serve as a reference for the engineering application and theoretical analysis of external cable steel box concrete composite continuous beams

Abstract:Design concept of a new method for externally anchored FRP sheet prestressed reinforcement, fully utilizing the characteristics of waveform toothed fixture anchors, using two ends fixed first and then middle tightened, forcing the geometric elongation of the FRP sheet to generate pre tension. Using the old bridge components removed from Chengdu–Chongqing Expressway, the experiment of externally anchored carbon fiber cloth prestressed reinforcement is carried out. The test results show that this method is very simple and convenient to apply prestress, and the technology is feasible. It does not need special tensioning equipment, and significantly improves the reinforcement effect. It has a very broad application prospect

Abstract:The large-tonnage prestressed anchorage system for the safety shell of nuclear power plants is an important and complex part of the construction of the safety shell. The static anchoring performance of the anchorage is measured through static load tests of the steel strand anchorage assembly. According to the requirements of the nuclear power design unit, the actual working conditions should be simulated during the static load test of the prestressed anchor of the nuclear safety shell, and concrete anchor blocks should be added at the ends. Compared with the conventional anchor static load test, the steel wire strands bend at the concrete anchor blocks, which greatly increases the difficulty of the test. This article introduces the static load test of prestressed anchors for nuclear safety shells under simulated actual working conditions. The success of the test has led to the application of domestically produced prestressed anchors for nuclear power plants

Abstract:Ultra High Performance Concrete (UHPC) is a new type of cement-based composite material with ultra-high mechanical properties, excellent durability, and excellent volume stability. This article introduces the basic preparation principle of this new composite material, and introduces the use of commonly used building raw materials such as cement, quartz sand, and mineral admixtures to prepare ultra-high performance concrete. Through comparative experiments, the types of mineral admixtures are studied The influence of fiber content and curing process on the compressive and flexural strength of ultra-high performance concrete has been determined to determine the optimal mix ratio. The experimental results show that this ultra-high performance concrete (UHPC) has good flowability. Under high temperature environment curing, the compressive strength of the specimen reaches 325MPa, and the flexural strength reaches 54MPa; Curing under natural conditions, the compressive strength of the specimen at 30 days is 187MPa, and the flexural strength is 35MPa. This paper then explores the application of this kind of ultra-high performance concrete in prestressed Structural engineering, replacing steel anchor plates and other products, and using the prestressed components prepared by it, all performance indicators meet the technical requirements, and the cost is significantly reduced, laying the foundation for the popularization and application of ultra-high performance concrete in prestressed Structural engineering

Abstract:On the basis of experimental research and numerical analysis, a new composite soil nail support technology was successfully designed and constructed for a soil cavern with a gross span of 10.5m and a gross height of 7.07m, and monitoring results and conclusions were presented. Its novelty lies in the use of composite soil nails to support large-span soil caverns, eliminating the secondary permanent lining, breaking through the traditional construction method of caverns, saving cumbersome mechanical equipment and expensive multiple trolleys, making construction convenient and feasible, providing a new type of support method for the construction of large-span soil caverns

Abstract:The pedestrian cable bridge of Wanjiazhai Dam on the Yellow River was originally a temporary structure. After more than ten years of application, it is now required to strengthen the superstructure of the main bridge according to the permanent structure system in order to make it a permanent structure. The main cable anchorage system of a cable bridge is the lifeline of the entire cable bridge, and its durability and reliability are key to the sustainable use of the entire cable bridge. Due to the use of imported steel wire rope systems from the 1950s as the main cable of the cable bridge, which is a construction turnover material, and the fact that the original anchorage system of the cable bridge used a structure of tight fitting and rope clamps, it posed significant challenges to ensure that the new reinforcement system worked together with the original system. After different experimental studies, a new combined anchoring system of "three piece clamping, epoxy mortar wrapping, and support box force transmission" was ultimately adopted. This system adopts special tensioning and top pressing processes, which can use the new clamping system to bear the force together with the original system, and has good gripping and protective effects. It has a good reference and reference value in the same type of structural system