Abstract
Aging building structure has become a world problem. This problem is particularly serious in developing and underdeveloped countries. The multihazard resilience and sustainability (e.g., seismic performance) decrease at the aging building. A construction method for strengthening aging-reinforced concrete buildings by wrapping structural members with carbon fiber sheets has been proposed and implemented in recent years. Authors aim to develop a seismic retrofitting method of aging concrete structural wall with a rectangular cross section using carbon fiber sheets. In this paper, authors examined the stress-strain relationship of concrete elements with rectangular cross sections reinforced by wrapping with carbon fiber sheets. Monotonic uniaxial compression tests were performed on 21 specimens using the ratio of the long side to the short side and the ratio of the element height to the short side of the concrete cross section, the weight of the carbon fiber sheet, and the chamfer radius of section corners as variables. The tests revealed that (1) the compressive strength decreases and ultimate strain increases as the ratio of the long to short side (longitudinal ratio) of the cross section increases even in a range the ratio exceeds 2 and (2) the ratio of the element height to the short side does not significantly affect the stress-strain relationship. Furthermore, authors proposed evaluation formulas for the constitutive law of concrete elements with rectangular cross sections including the longitudinal ratio which exceeds 2 reinforced by carbon fiber sheets and confirmed that the formulas can reproduce the test results with good accuracy.
Highlights
A construction method for strengthening aging-reinforced concrete buildings against earthquakes by wrapping structural members with carbon fiber sheets (CF sheets) has been proposed and implemented in recent years [1,2,3,4]
Monotonic uniaxial compression tests were performed on 21 specimens of concrete elements reinforced by wrapping with carbon fiber sheets. e following are our findings within the scope of the specifications of specimens used in the tests: (1) As the aspect ratio of the concrete section increases, the compressive strength decreases, while on the contrary, the ultimate strain determined by the rupture of the carbon fiber sheet increases and ductility capacity improves
(2) For the experiments in this study, there were no changes observed in the stress-strain relationships of concrete elements reinforced with the carbon fiber sheet as the ratio of height in the direction of axial compression of the element over the short side of the cross section changes
Summary
A construction method for strengthening aging-reinforced concrete buildings against earthquakes by wrapping structural members with carbon fiber sheets (CF sheets) has been proposed and implemented in recent years [1,2,3,4]. Ercan et al [9] clarified experimentally that the reinforced concrete beam-column connections strengthened with carbon fiber-reinforced plastic (CFRP) sheets increase the bearing capacity and ductility. New-type mixed structure connection consisting of the reinforced concrete column and steel beam (RCS) is developed [10]. E authors have proposed seismic retrofitting using the wrapping method of structural members with CF sheets for the problem of flexural failure in aging columnless The method had not been used on walls or other cross sections with extremely large aspect ratios. e authors have proposed seismic retrofitting using the wrapping method of structural members with CF sheets for the problem of flexural failure in aging columnless
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