Abstract:The "Material Inspection Laboratory" of the city of Milan, Italy, as an official body, has completed a load transfer test of the cast anchor plate of the clip anchor to confirm the load capacity and safety of the anchor plate used in concrete structures. It is based on the European standard ETAG 013 "Post-tensioned Assembly of Prestressed Structures" and its "Understanding Document "(published in December 2007). All 28 European member States implement this standard, and many non-regional engineering units also adopt it. The new anchor national standard (GB/T 14370) to be implemented in China is basically consistent with the European standard. This test report is of great reference value to the present situation of our country. In China's prestressed industry, most practitioners are still relatively unfamiliar with the "load transfer test", and will soon encounter the work requirements of this test. In this paper, the test process is comprehensively sorted out and explained according to the chapters of the original test report, and the relevant points of European standards are added, hoping to reduce readers' doubts.

Abstract:As one of the widely used structures in modern civil construction, cable system as the main bearing component is very important to the safety and service life of the whole structure. At present, the main detection methods for cable system include visual inspection, cable force measurement, acoustic emission, ray, magnetic, ultrasonic, magnetostrictive guided wave detection, etc. Based on the brief discussion and comparison of the above testing methods, it is pointed out that the magnetostrictive guided wave nondestructive testing technology has become a widely used new nondestructive testing method for cables because of its unique advantages such as large detection length, wide coverage of structure area, far away from the difficult area to be detected by testing instruments, and no need to excavate or remove the coating layer and anti-corrosion layer. In this paper, the principle, sensor, experimental research, instrument development and application of magnetostrictive guided wave detection are reviewed, and the current research difficulties, hot spots and future research trends of this technology are summarized.

Abstract:According to the special construction conditions of mountain area, the construction technology of the main beam erection of suspension bridge by rail cable slip method is put forward. In this method, the main cable and sling of the suspension bridge are used as the load-bearing structure, the lower end of the sling is connected with the sling saddle, the sling is supported on the rail cable, and the section beam is transported by the beam carriage moving on the rail cable. After reaching the installation position, the cable load crane is used for vertical hoisting and installation. Based on the construction of Aizhai super-large suspension bridge, the paper introduces the composition and key technology of the beam erection system with rail cable slip method, and the structural design and calculation analysis of the core components, such as the saddle, beam carriage and rail cable system. The test methods and results of the whole scale model test and full scale model test for the whole beam frame system are introduced, and the practical engineering application is summarized. The results of model test and engineering application show that the rail cable sliding frame beam method can quickly realize the erection of the main beam of the suspension bridge, and has good safety and economy, and has a broad application prospect.

Abstract:In order to adapt to the reality and demand of high bearing capacity of modern long-span bridge, the cable must be crossed to the super-large hole position. Overem has been committed to the research of the cable system of steel strand, based on the international code as the design basis, according to the code and engineering design requirements, the fatigue test of the cable component of the OVM250 ultra-large hole cable system fatigue stress range meets and exceeds the requirements of the international code, the test results show that the OVM250 ultra-large hole cable fatigue The performance reaches the international advanced level.

Abstract:In this paper, based on the traditional wireless strain testing technology, a wireless dual-core stress testing device is designed to solve the synchronization problem of wireless network from the hardware architecture. The equipment is mainly composed of three parts: measurement circuit, data processing unit and radio frequency unit. The radio frequency unit uses an independent data processing module to form a dual-core system with an external data processing module. When synchronizing data acquisition, the clock in the radio frequency unit sends pulse signals directly to control the acquisition circuit, which greatly reduces the time delay and improves the synchronization accuracy of data. This paper mainly discusses the principle of strain measurement, wireless strain acquisition device, acquisition circuit, dual-core data processing circuit and the realization of the final product. Finally, the stress test is carried out in the process of opening and closing the gate support arm with this equipment. The test results show that the equipment fully meets the requirements of engineering test, the system performance is stable, the measurement accuracy and synchronization accuracy are high.

Abstract:OVM prestressed carbon fiber plate reinforcement technology is a new way of bridge reinforcement, anchorage as a key component, its anchoring performance directly affects the safety of the system. It has been proved by a large number of tests that its anchoring efficiency is very high, and it can meet the tensile technical requirements of carbon fiber plate.

Abstract:The cable network installation of the National Astronomical Observatories FAST project includes 2225 main cable nodes, 6670 main cables and 2225 lower cables, all installation work needs to be completed in the air, requiring high precision and difficult construction. In order to avoid excessive stress in the cable network during installation and meet the stress requirements of the ring beam, the entire cable network is divided into 5 construction areas symmetrically and equally during construction, and each area is constructed simultaneously. During construction, a large number of suspended ropeways are required for assembly. Among them, the construction channel is a fixed ropeway, which needs to bear a large force, and the construction ropeway is constantly transferred with the installation progress.

Abstract:The spherical cable network structure of the FAST project of the National Astronomical Observatory is composed of 2225 nodes,6670 main cables and 2225 lower cables. After the installation of the structure, the cable force of the cable network needs to be adjusted to meet the design requirements of the structure. The spherical cable network of FAST Project is connected with the ring beam through 150 edge main cables, the edge main cable adopts the cable structure with adjustable length, and the other main cables are the non-adjustable cable structure with fixed length. The cable network nodes are connected to the ground anchor through 2225 lower cable. The geometric position of the cable network is realized by the adjustment of the edge cable, and the late change of the node of the cable network is realized by the adjustment of the lower cable. This paper introduces the construction technology of the main cable force adjustment of the edge of FAST spherical cable network structure.