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Code and Title:
     ICTAG I575: Development of Retrofitting Techniques for Existing Structures

Principal InvestigatorAssist. Prof. Dr. Ugurhan Akyüz (homepage)


     The seismic repair and/or strengthening philosophy generally consist of a) system behavior improvement and b) member repair/strengthening. Although these two general approaches can be applied separately in some cases, they generally are combined. In the system behavior improvement technique, the general philosophy is to introduce a new lateral load resisting system, which will increase the lateral strength and the lateral stiffness of the existing system, which is generally a non-ductile frame with inadequate lateral stiffness. This principle relies on the safety of the existing structure under gravity loads. Various techniques based on this principle have been developed and applied in the past. Among them, the most widely used technique is the formation of new stiff walls through infilling some bays of the existing frame with reinforced concrete infills. In general, the new stiff elements are placed in such a manner as to minimize the floor torsion. Use of infilled frames as a method of seismic behavior improvement for existing structures is presently a very common application in Turkey. This approach was first proposed following the pilot tests made by the METU staff on the infilled frames, and was gradually established in practice on the basis of the underlying experimental research. In addition, the column jacketing is among the commonly used repair/strengthening techniques in Turkey. The efficiency of the method was investigated by a number of test series concentrating on various aspects of the problem.

      All these techniques are applicable at the cost of a certain discomfort to the occupants and, the application of these techniques in the rehabilitation of undamaged buildings may not very practical. In the scope of this research project, the development of new strengthening techniques is one major achievement. For this purpose experimental research programs will be initiated. In these research programs the use of new materials in system and member rehabilitation will be studied. It is intended to perform quasi-static tests on model frame structures, aiming at the investigation of the post intervention seismic behavior of frames retrofitted with various techniques to be proposed.

     Besides overall system behavior improvement, repair and/or strengthening of some reinforced concrete elements is sometimes required if their capacities are not sufficient to meet the strength demand of a major earthquake. In the past, many methods were proposed for strengthening of R/C members. Depending on the desired earthquake resistance, the type of elements and their connections members can be repaired and/or strengthened by epoxy injection, by jacketing or fiber reinforced plastics (FRP) or carbon fiber (CF) wrapping.

     Another objective of the proposed study is to develop alternative and yet feasible member strengthening techniques for structures in service.

     At the end of these studies, rapid and yet reliable rehabilitation methodologies for Turkey will be developed.

Keywords: Earthquake, reinforced concrete, repair, strengthening, earthquake resistance, earthquake safety, lateral load resisting system