Structural Performance of Strengthened Box Steel Beams with composite materials

Abstract
The main objective of the current study is estimate the structural performance of box steel beams strengthened with composite materials. Eight steel box beams (typical beam and seven strengthened beams) were tested in four-points loading. The beam samples are 50x50x1000 mm. Four out of the seven beams were strengthened with steel elements. The other three beams were strengthened with composite materials; CFRP and GFRP flexible sheets. The sheets were wrapped around the whole section of beams at the critical locations. The tested beams also were simulated by the Finite Element (FE) method using ANSYS program. The numerical results in terms of load–deflection curves, load-strain curves and failure modes were compared with experimentally measured data. Also the normal stresses distribution for the eight beams as obtained from the numerical model were presented. Additionally the comparisons between the results of the eight beams were presented and discussed. From these results, it was observed that the predicted FE results are in good agreement with the experimental results. Also the experimental results showed that the failure in the strengthened beams with carbon fiber occurred in the top flange and the upper part of the two webs due to debonding and breakage in CFRP.