SEISMIC EVALUATION AND ECONOMICAL STRENGTHENING OF REINFORCED CONCRETE BUILDINGS

Seismic evaluation standard for existing reinforced concrete buildings is outlined which has been in practical use from 1970’ in Japan. An effective, efficient and economical method is introduced using polyester sheet for strengthening old and non-ductile buildings. The remarkable effectiveness on the improvement of deformability has been verified through a various seismic tests such as number of static column tests and a shaking table test of frames, and already in practical use for columns. The verification test on walls strengthened with the polyester sheet was conducted recently. Since the conventional detail for strengthening walls with fabric sheets is generally complicated, a new detail for strengthening walls was developed. The bare reinforced concrete wall failed in a brittle shear failure mode, while much higher shear strength and deformability after flexural yielding were observed generally for the walls strengthened with the sheet. The new detail improved the deformability much more than the conventional detail.