Analysis of Interfacial Mechanical Properties of Steel Beams Strengthened with CFRP Sheets under Temperature and Creep

Abstract

Under the combined action of temperature and creep of CFRP (Carbon Fiber Reinforced Polymer) sheet, the interface between CFRP sheet and steel beams which are strengthened with CFRP sheet will produce relative slip. This slip will affect the interface interaction, reduce the bearing capacity and stiffness of members as well as increase the deformation. In this paper, the elastic method is used to introduce the creep effect of CFRP sheet and the temperature effect of steel beam. The calculation formulas of interface slip between CFRP sheet and steel beam, CFRP sheet tension and steel beam deformation under the combined action of temperature and CFRP creep are established. The accuracy of the analytical formula is verified by finite element analysis using the software ABAQUS. The results show that the CFRP sheet tension is smallest at the beam end while largest at the middle of the span. When the stiffness reaches about 3 ka, CFRP sheet tension basically does not change. When the temperature increases by 5 °C, the tensile force of CFRP sheet increases by about 3.7 kN, 1.8 kN and 2.3 kN, respectively. The increase of stiffness under creep has little effect on the change of CFRP sheet tension. The deformation is largest in the middle of the span while smallest at the beam end. Stiffness, temperature (5–25 °C), CFRP thickness and stiffness under creep have little effect on deformation. When the load increases by 5 kN under creep, the deformation increases by about 2.2 × 10−7 mm, 1.8 × 10−6 mm and 9.4 × 10−7 mm, respectively.

The Use of CFRP for Structural Reinforcement—Literature Review

“…Steel beams strengthened with CFRP tapes are particularly exposed to the CFRP sheet's creep effect. Zhang et al [19] introduced an elastic method, which is used to insert the CFRP sheet's creep effect and the steel beam's temperature effect. Computational formulas of interface skid between the CFRP sheet and the steel beam, as well as stresses in the CFRP sheet and steel beam deformations under combined influence of temperature and CFRP creep, were presented.…”