Experimental Investigation of the Behavior of a Lattice Steel Column Repaired with Pultruded GFRP Profiles

In this paper, a series of joint tests and full-scale structural tests were performed to assess the effectiveness of pultruded glass fiber-reinforced polymer (GFRP) profiles for rehabilitating lattice steel columns. The data for the displacements and strains of typical members were recorded. The experimental results showed that the failure modes are generally identical for the original column, the column restored using angles, and the column that adopted the stiffer GFRP-to-steel bolted joints (using steel cover plates, bolts, and nuts) repaired with pultruded GFRP sections. In contrast, the failure pattern of the column that used the ordinary GFRP-to-steel bolted joints (only using bolts and nuts) was not the same. Additionally, the ultimate strength of the specimen that employed the stiffer GFRP-to-steel connections was slightly higher than that of the specimen retrofitted by angles, and the ultimate capacity of the sample that adopted the ordinary GFRP-to-steel connections was significantly lower than that of the sample restored by angles because of the premature failure of the ordinary GFRP-tosteel connections. Additionally, better coordination in the working capacity of the GFRP members was exhibited by the restored structure. Furthermore, joint slippage dramatically decreased the stiffness of the structure, and its influence on the load-bearing capacity and failure mode is not obvious if the structure is subjected to the transverse loading. The conclusion is that pultruded GFRP profiles can be used for retrofitting of lattice steel structures and that the performance of GFRP-to-steel connections is a key factor in this novel method. This preliminary investigation into the feasibility of using pultruded GFRP profiles in the repair of lattice steel structures shows promising results and provides a basis for the development of other FRP shapes for application in the rehabilitation of lattice steel structures. (C) 2014 American Society of Civil Engineers.