Glulam members strengthened by carbon fibre reinforcement

Abstract

Glulam members often become large in cross section where heavy loads should be carried. In some applications this may cause problems if limitations on height are posed. A possible solution is to reinforce the member by e.g. bonding fibre reinforced polymer (FRP) on the beams or between the glulam lamellas. The aim of this paper is to investigate the possibility of strengthening glulam beams by the use of pultruded rectangular carbon fibre rods and to establish the anchoring length for this system. Tests were performed in three different series completed by a reference series, 10 specimens altogether. All tests were performed as short-term experiments in four-point bending. The experimental results were compared to analytical models in several aspects. The overall capacity of the beam was established using an analogy with concrete beams. Special attention was made to establishing the anchoring length of the reinforcement bar, since this is governing to avoid premature failures. The anchorage length was tested and an analytical model established. The agreement between the analytical critical anchoring length and the test result was satisfactory. The proposed reinforcement method increased the short-term flexural load-carrying capacity by 49–63% on average.