Application Of Hydraulic Jack-up Unloading Technique In Strengthening By Bonding

Since the twentieth century, with the rapid development of the construction industry, a large number of concrete structures have been built up. However, due to the poor management and other technical reasons such as the design, reconnaissance and construction, there are more or less potential security hazards in these existing buildings. Appropriate and effective corresponding measures must be taken without any delay to deal with these problems, otherwise, serious accidents might occur. Under such circumstances, structural strengthening technology has emerged and developed.In recent years, with the development of strengthening technology, bonded reinforcement has become mature and widely used and achieved great successes in the structural strengthening. Its theoretical perfection and increase in strengthening materials have also contributed to its further development. With the shortcomings of the secondary load in the traditional technology considered, this paper mainly deals with the hydraulic jack-up unloading technique. By the use of the performance analysis function of Software SAP2000, the analogue simulation was conducted for two bonded reinforcement techniques. Stress of members, bending deformation and ultimate bearing capacity were analyzed and compared, comparative results showed that the bending stiffness and ultimate bearing capacity of the structural members had changed considerably when using hydraulic jack-up unloading technique in strengthening by bonding. Compared with the traditional technique, the mechanical properties of the structure and the strengthening effect were both greatly improved when using the new hydraulic jack-up unloading technique,, having brought high economic effectiveness.This paper consists of the following contents:Chapter â…  introduces the research background and significance, the current situation of the application of hydraulic jack-up technology, as well as the main contents of this paper.Chapter â…¡ describes the method of bonding steel plates and the technique of carbon fiber reinforced plastic (CFRP) sheets, based on the traditional bonding technology, this paper adopts the hydraulic jack-up unloading technique in strengthening by bonding, and describes its technical principles, contents and the main points of the process. Chapter â…¢ mainly introduces the computational formulas of the short-term stiffness in the current specifications of the reinforced concrete members, and emphasizes the computation and influencing factors for the short-term stiffness of concrete members, described in Code for Design of Concrete Structures. The concrete is normally working with cracks, so this paper adopts the short-term stiffness in calculating the reinforced concrete members. On the basis of the computational formulas, this paper puts forward the computational formula for the short-term stiffness of concrete members after using the strengthening by bonding. Eventually, according to the current theory of strengthening, this paper offers the computational formula for the stress of strengthening materials.Chapter IV, as a case study of an engineering case, compares the different stress states by adopting the traditional bonded strengthening technology and hydraulic jack-up unloading strengthening technique. Finally, this paper verifies that the mechanical properties of the concrete members when using the hydraulic jack-up unloading technique can be significantly improved.Chapter V serves as conclusions and suggestions.