AN EXPERIMENTAL ST UDY OF DEFECTُSEFFECTS IN DETAILING ON THE AXIALBEHA VIOR OF EXISTING CONCRETE COLUMNS

In many countries, Reinforce d concrete structures are traditionally designed without seismic provision. In particular, non-seismic detailing is specified in the columns. Seismic rehabilitation of old buildings has been a major challenge in recent y ears. The first step in seismic rehabilitation is e valuation of the existing capacity and the seismic behavior.The purpose of this research i s the study of defectُs effects in the transverse reinforcement details such as: bend type of transverse reinforcement, anchorage of transverse reinforcement, spacing and volume of transverse reinforcement, on the axi al behavior of reinforced concrete columns in th e existing buildings. On this basis, for investigation of the seismicmmbehavior of RC columns of a real old building in Iran which has been designed and constructed by E uropean engineers in 1940,four concrete specim ens with half-scale with the cross section dimension of300 x 300 and the length of 1000 mm, have bee n tested on the effect of vertical axis in the structures laboratory of faculty of engineering of University of T ehran. It should be noted that, all specimens are 28-day compressive strength of 25 Mpa. Samples are made with similar characteristics of old buildings and reinforced with plain bars by 90 and 135 degr ee bending of transverse reinforcement. Tests results indicated that the column specimens with non-seismic reinforcement detailing, possesses low ductility capacity. In addition, ratio, bending and anchorage of trans verse reinforcements are the most important beneficial effect on the stress-strain behavior of concrete .

Keywords:

Old RC Column , Transv erse Bar , Detailing , Stress-Strain Curve , Confine ment