In this paper, the efficiency of a new strengthening technique is evaluated. Strengthening-by-Stiffening, or SBS, utilizes out-of-plane stiffness of pultruded composite sections to enhance the local buckling properties of thin-walled steel structures. This new method has been tested experimentally in a pilot study that showed its potential in improving the shear strength of steel beams. Not only are high strengthening levels achieved using SBS impressive, but also the cost at which they are achieved. SBS relies on the geometric stiffness of pultruded sections. As a result, in this research we utilized glass fiber reinforced polymer (GFRP) sections rather that the more expensive high-modulus (HM) carbon fiber reinforced polymer (CFRP) materials. The performance of SBS stiffened beams depends on the bond between the composite section and the stiffened plate, which takes place on the flange of the composite section. A finite element model was built and calibrated using experimental results. The model was then used to assess the effect of contact flange area on SBS efficiency. GFRP stiffeners with different bond areas (flange widths) were considered while maintaining the overall stiffness constant. It was shown that the efficiency of SBS is affected by the bond area, which is expected since the failure mode is governed by debonding of the stiffening GFRP element. Strengthening levels ranged from 40% for the smallest to 60.2% for the largest flange bonding area. Based on the findings, conclusions are drawn and recommendations for future research are made.
展开▼
