Evaluating the Efficiency of Strengthening Hot-Rolled I-Sectioned Steel Beams by using Additional Plates and Inclined Stiffeners with Various Widths

Abstract

Abstract In this research, an attempt has been made to study the efficiency of strengthening hot-rolled I-sectioned steel beams by using additional steel plates welded at top and bottom flanges and inclined stiffeners with various widths welded at both sides of the web. This addition was incorporated to increase the moment of inertia about x and y axes (Ix-x and Iy-y) in order to reduce the vertical mid-span deflection as well as the horizontal strain and to prevent (or at least postpone) the occurrence of the lateral buckling. It was found that, the basic governing role of the additional top and bottom steel plates was to enlarge (Ix-x) for the purpose of decreasing the vertical mid-span deflection and the horizontal strain, while the major contribution of the inclined stiffeners was found that primarily its configuration provides some kind of lateral support and secondarily through increasing (Iy-y). It was also found that the usage of this type of strengthening leads to increase the ultimate load value in addition to the pre-mentioned reduce in deflection and strain. On the other hand, the failure mode is noticed to be changed from “lateral buckling” type (for the non strengthened beams) to a “plastic hinge” type at mid-span (for the strengthened beams) which is attributed to letting the strengthened beam attain its full flexural capacity through preventing (or postponing) the occurrence of lateral buckling.