Experimental and Numerical Investigation of CFRP-Strengthened In-Plane Curved Steel Beams with Circular Hollow Cross-Section Subjected to Transverse Load

In-plane curved steel beams with circular hollow sections (CHSs) are widely gaining appeal in bridges. Strengthening such elements for increased demand or decreased strength due to environmental effects or fatigue, without affecting the usage of structure, is a timely need. Carbon fiber-reinforced polymer (CFRP) materials have been a promising solution for such situations. This paper investigates the flexural behavior of CFRP-strengthened vertically curved steel beams with CHSs. Sixteen such beams, each with a span of 1200 mm and having four different radii of curvature, i.e., 0 m, 2000 mm, 4000 mm, and 6000 mm, and retrofitted with a range of CFRP bond lengths, are considered. Numerical models of these beams are developed and validated using the results of tests performed by the authors, and the validated models were used to simulate bond characteristics and structural performance. Optimum performance was noted in the specimens strengthened with CFRP fibers attached in the axial direction of the members, irrespective of their curvature. On average, strength enhancements of 21% and 14% were obtained in CFRP-strengthened straight and curved beams, respectively. Detailed bond characteristics presented in this paper under transverse loads yield important data for researchers, designers and material developers to strengthen in-plane curved steel members.