Study On Loading Behavior Of Concrete Beam Strengthened With External CFRP Tendons

With the development of road and bridge construction in our country, the traffic flow and class of loading are growing larger, many existing bridges can not meet the demand for bearing capacity. In a many of existing bridge reinforcing techniques, external pre-stress strengthening technology is one of the most efficient reinforcing methods. As a new-type material, carbon fiber polymer materials has become a favorite of all the people in the engineering field due to its advantages. Among these materials, CFRP is mainly applied in structure as new material instead of steal, or which is applied strengthening concrete structure as external tendon.Anchoring device is one of important structure of the external pre-stressed bridge, which is the only structure tied in externally pre-stressed tendons and concrete, except deviators. External applying pre-stress is totally maintained by anchoring system, and transfers to structure through anchoring device.Once the anchoring device has the problem, the problem will induce the invalidation of the pre-stressed system. Therefore, anchoring device must provide higher dependability and security than normal internal pre-stressed force. In addition, due to the spatial stress is complex, non-uniform stress distribution, and local stress is over loaded, it is very significant to adopt reasonable space structure analysis and master the actual stress distribution. The contents of this research work include:(1)Bonding-friction anchoring is adopted, and relative connection and bonding technology with high strength bolts is briefly presented combine with the working principle of bonding-friction anchoring. While, focus on the characteristics of CFRP and anchorage, the anchoring device is designed based on existing design code.(2) The designed anchoring device is experimentally researched in this work. Two tested beams are made to test the mechanical behavior of linear type and folded type anchoring devices, which are performed in CFRP tension period and tested beams impact loading process. The distribution rules of strain and displacement of anchoring toothed plate and bolts is analyzed, and the dependability of anchoring device is validated in this research.(3) Based on the experiment, whole beam segment model is established by ANSYS finite element software,and FEM (finite element method) is used in bonding-friction anchoring device. The comparative analysis of theoretical results and experimental results is performed, and the calculation method is validated in this research.