حبیب اکبرزاده بنگر

This paper reports the results of an experimental study that involved the investigation of the axial capacity of re-damaged specimens repaired by expansive cement concrete and CFRP wrap. Specimens were subjected to axial compressive loading and their resulting stress-strain curves were recorded. Since the at sides of the square samples remained uncon ned, the cross-sections of the tested specimens largely remained uncon ned. The FRP jacket was e ective only along the two diagonals of the cross-section. Con nement is generally more e ective in specimens with circular cross-sections than in those with square ones. The change in cross-section for some of the specimens from square to circular ones was implemented. To modify the shape, expansive cement concrete was utilized to ll the gap between the circular and square cross-sections. The test results indicated that heating up to 500C caused a severe decline in compressive strength and the elastic modulus of concrete. Two layers of CFRP wrap around the concrete not only compensated the drop in compressive strength, but also increased the strength beyond that of unheated specimen. However, the e ect of wrapping alone on the sti ness and the elastic modulus is negligible. The heated square specimens that were rst subjected to shape modi cation and, then, wrapped by CFRP sheet experienced an increase in the strength and the elastic modulus. Therefore, the sti ness and the compression strength of re-damaged square concrete specimens could be compensated fully by the use of shape modi cation and CFRP wrapping of the cross-section.