Abstract:The fatigue properties of corroded reinforced concrete beams reinforced with non-prestressed arylon fabric (AFRP) and prestressed AFRP with permanent anchorage are studied. Through fatigue test, the influence of prestress level and steel corrosion degree on fatigue failure mechanism, fatigue life and deflection of reinforced beams is discussed. The test results show that the fatigue failure mechanism of prestressed AFRP and non-prestressed reinforced beams is the same, and both are fatigue fracture of longitudinal reinforcement. The fatigue resistance of prestressed AFRP reinforced corroded concrete beams is obviously better than that of non-prestressed reinforced beams. The higher the prestress level, the higher the fatigue life of moderately corroded beams after reinforcement; The higher the corrosion rate, the lower the fatigue life of the beam, and the reduction of fatigue life of the severely corroded beam is more obvious than that of the moderately corroded beam. The equivalent fatigue notch coefficient Kf of the corroded longitudinal bar is obtained by comparing it with the plain steel bar. The results show that the fatigue life of corroded beams decreases obviously with the increase of steel bar corrosion rate. Based on the test results, a formula for calculating fatigue life of moderately corroded reinforced concrete beams reinforced by prestressed AFRP is established, which can be used as a reference for bridge reinforcement design.

Abstract:When the Fiber Reinforced Polymer/Plastics (FRP) bars or cable are applied to the cable system of cable bearing bridge, the bonded anchorage and the clip anchorage have their own limitations. According to the characteristics of common cable anchorage system, combined with the research results of FRP bar clip anchorage and bond anchorage, the composite anchorage of FRP bar was proposed. The composite anchorage consists of a wedge anchorage at the rear and a bonded anchorage at the front. The wedge anchorage part includes an anchor cup, a clamp with concave teeth, an aluminum sleeve and a plastic film, and the bonded anchorage part includes a steel sleeve and Reactive Power Concrete (RPC), the bonding medium. The effects of the length of anchor cup, the length of steel sleeve, the pretension force of clip and the pretension force of reinforcement on the anchoring performance of composite anchors were studied by static load test. The results show that the maximum limit load in the composite anchorage specimens is 208kN, and the corresponding anchoring efficiency coefficient is 104%, greater than 95%, which meets the requirements of the code. The reasonable combination of anchoring length of the two anchoring forms of composite anchorage is as follows: for no pretension anchorage, the length of the anchor cup is 40mm and the length of the bond anchoring is 100mm; For pre-tensioned anchors, the length of anchor cup is 60mm and the length of bonded anchorage is 60mm. The calculation formula of ultimate load of the composite anchorage has good applicability.

Abstract:In recent years, the frequent occurrence of large earthquakes in the world has aroused people's attention to this special unsafe factor. In China, various kinds of vibration isolation devices used in bridge vibration isolation design technology have also been introduced. Among them, there are several kinds of rubber isolation bearings of small and medium tonnage that are widely used. What is the difference between the performance of these rubber isolation bearings and whether the isolation effect is the same is the topic that the article will discuss.

Abstract:The main bridge of Lhasa Najin Bridge is a three-tower low tower cable-stayed bridge with a span of (70+117+117+70)m. In order to study the performance of the bridge tower segment with a small radius (the radius of the splitter tube is 2.5m) and a large cable force (the maximum radial uniform load of the cable in the saddle segment is 2372kN/m), the finite element model of the 1/4 tower segment is established by ANSYS for stress analysis, and the full scale model of the bridge tower is made for test, so as to test the structural stress, the relationship between the cable and the cable The friction resistance between the cable saddles, the gripping force of the epoxy mortar in the anchoring device on the cable. The results show that it is safe and reliable to use small radius pipe for the bridge tower, and the friction resistance and anti-sliding force of the cable saddle meet the application requirements. Based on the finite element analysis and test, some suggestions are put forward, such as strictly controlling the processing and positioning accuracy of the steering saddle, ensuring the compactness of concrete pouring, and ensuring the simultaneous construction of both sides of the main beam.

Abstract:This paper introduces a new type of rock anchor system based on carbon fiber cable and ultra-high performance concrete, and conducts relevant experimental research on these two new materials. Through the test results, the performance indexes of anchor cable and concrete and the selection of raw materials are determined, and the production and construction technology are formulated.

Abstract:The round tower anchor plate adopts the structure form of multi-level steps to disperse the anchorage force and improve the bearing capacity of the anchor plate. This paper takes OVM.M15-9D and OVM.M15-12D anchor plates as examples, by changing their structural forms, that is, removing the end two steps, using ANSYS finite element analysis and load transfer test methods, to compare and study their effects on the bearing capacity of anchor plates, and analyze the force transfer forms of multi-step steps under the anchor concrete.