Stiffness evaluation of steel rolled shapes strengthened with high-strength fiber reinforced cementitious strips

Abstract

High strength cementitious grout has been widely used as repair material in reinforced concrete structures. However, in steel structures its usage is limited. The aim of this project was to incorporate a glued precast strip of high strength cementitious grout with steel fibers (HSFRCG) and determine its effect on the structural performance of steel rolled shapes and on its load bearing capacity. To fulfil this aim, flexure, compression and direct tension strength tests were first conducted to determine the compressive, flexural and tensile strengths of the precast. A tensile strength test was also conducted between the concrete strips and steel plates to determine the bonding strength of Sikadur C31 resin. Afterwards, two IPE 220 beams reinforced with HSFRCG were tested under two point-loading in the laboratory to determine its effect on the beams’ structural behavior. Based on material testing, the compressive and tensile strength of the mixture were 82.91 MPa and 6.29 MPa respectively. Two cold bent steel beams labelled as TG1 and TG3 were used in the test and reinforced with 1cm and 0.5cm thick HSFRCG strips respectively. The beams reached maximum loads of 171.912 kN and 168.048 kN respectively (based on two-point loading where each load in labelled as P) and failed in localized buckling and torsion rather than bending. Stress-strain data showed that the beams were still in the elastic range and far from yielding. Finite element models representing TG1, TG3 and a control model were developed using ABAQUS CAE 2019 to compare results with experimental data. In conclusion, HSFRCG precast strips help in increasing the flexural capacity of steel beams. However, attention should be given to other types of failure such as crippling and twisting to ensure effectiveness.