Experimental study on the behaviours of spliced reinforced concrete girders strengthened with NSM CFRP bars

Abstract

This paper presents the results of an experimental investigation of spliced and non-spliced reinforced concrete girders strengthened with near surface mounted (NSM) CFRP bars. Six reinforced concrete girder specimens were tested, divided into two groups according to their support condition: simply supported and continuous. Each group thus contained three girders; one girder of each group was single segment without splicing, as a control for comparison purposes. The second girder was spliced in three precast segments without strengthening, and the third girder of each group was spliced in three precast segments strengthened with NSM CFRP bars at the bottom surfaces of the two splice regions. The main variables studied were support conditions, presence of the splicing technique, and strengthening with NSM CFRP bars. The strengthening of spliced girders was achieved by using two bars of 6 mm diameter CFRP in the longitudinal direction. The results for the simply supported group showed that this strengthening resulted to an increase in ultimate load of 11. 25%, as compared with that seen in the spliced girder without strengthening, and of 5.4 % when compared with the control girder. This strengthening method also reduced the maximum deflection by about 23%. The results also showed that strengthening the continuous girder resulted in an increase in ultimate load by 3.76% compared to the spliced girder without strengthening, and the maximum mid-span deflection was reduced by 8.7%. It was also found that the ultimate load of the control girder was greater than that of the strengthened girder by 2.54%. These results indicate that strengthening with NSM CFRP was more effective within the simply supported group than in the continuous group.