鹽害損傷된 鐵筋콘크리트構造物의 下部大斷面 補强에 관한 硏究

Abstract

This paper deals with the strengthening method for the Increase durability of the reinforced concrete structures with Chloride Damage, and the purpose of this research is to develop the construction method and materials for extending the lower large section of the structures which is set up on the sea. Accordingly, a reinforced concrete pier, which has serious damage at the lower large section, is adopted as the subject structure for the study. A close safety inspection is taken on this structure and the utilizing condition and the structural capacity should be taken into consideration, it needs mending, reinforcement and limitation of using. Besides, it also needs its lower large section to be extended so that it can resist the increased load up to about 30% heavier than one of existing design. The choice of an method of repairing or extending the lower large section for the structural reinforcement like the matter in this study, the following components are necessary. They include weather condition of the ocean surroundings, environmental pollution, and the limit of working time by the difference of the ebb and the flowing of the tide. They also contain the solution of the problems of concrete structures forward the opposite direction 300～500mm from the lower to the upper, Repeating the work by intervals several times can get more or less thick. In addition, by preventing cold joint from working among layers, the wet jet spray method which unifies the concrete structures and increases the utilizing and durability of the concrete structures, is chosen. In this study, the mock-up tests on a model structure, which is a similar structure, are executed according to the repairing and strengthening method which are applicable to extending the lower large section of the reinforced concrete structure set up on the sea, and the application and problems are examined. As a result of the Mock-up tests, the wet spray method is suggested to be the most suitable for the extending the lower large section of the reinforced concrete pier. The lower large section extension work of the subject is executed with the newly-developed material and the method for strengthening, and as a result of the quality inspection, the material and method prove their superiority since the compression and adhesion strength of the concrete are huge, and the adhesion between the glass fiber and the section extended is great. In conclusion, the wet jet spray method increases the safety rate of bending enormously. the durability and the utilizing of cracking width are found very satisfactory because cracking width in all the section decreases rapidly below the permitted cracking width. As the material and the strengthening method developed in this study bring about little possibilities of polluting the ocean, make it easy to operate on the sea, and have great adhesion not only between the existing and new concrete but also among each mortar layers, they are considered to be very suit to strengthening and extension of the reinforced concrete structure set up on the sea.