Stress–strain model for FRP confined heat-damaged concrete columns

Analytical model to predict axial stress-strain behavior of heat-damaged unreinforced concrete columns wrapped by FRP jacket

“…( 35) v) Assume a level of axial strain (ε c ) vi) Calculate the corresponding axial stress (f c ) using Eq. ( 10) vii) Draw f c versus ε c relationship In the present study, the well-calibrated models developed by Shayanfar et al [28] was followed to calculate the mechanical characteristics of unconfined heat-damaged concrete columns (f T c0 and ε T c0 ), as presented in Appendix C. Furthermore, to calculate axial strain (ε c0 ) corresponding to f c0 , the well-calibrated formulation recommended by Shayanfar et al [36] was adopted as ε c0 = 0.0011 31) and Eq. (32).…”

“…Despite these FRP confinement-induced improvements, the likelihood of FRP hoop rupture at a relatively low level of axial deformation increases by exposure temperature, resulting in a reduction in terms of axial strain ductility of FCHCC/FCHSC compared to FCCC/FCSC ( [4][5][6][7]). Beyond the exposure temperature of 400 • C, Shayanfar et al [28] demonstrated that as a consequence of the degeneration of micro-into meso-and macro-cracks, thermal-induced damage leads to a noticeable increase of the axial deformation of FCHCC/FCHSC. Hence, axial response of FCHCC/FCHSC converts from a parabolic-linear stress-strain relation into an almost linear one, by increasing exposure temperature.…”

“…In the present study, to calculate the mechanical characteristics of unconfined heat-damaged concrete columns (f T c0 and ε T c0 ), the models developed by Shayanfar et al [28], calibrated based on a large test database, was followed. For the calculation of f T c0 , the following equation of Eq.…”

“…(C-1) was proposed as: where γ f is the calibration factor reflecting the effect of concrete strength on the magnitude of the decrease of f T c0 with respect of T m . Based on Shayanfar et al [28]'s recommendation, ε T c0 as a function of ε c0 (= 0.0011 [36]) can be calculated as: where α T0 presents the calibration factor reflecting the influence of T m on axial strain enhancement caused by thermal damage.…”

Nonlinear bond-slip model for fiber-reinforced polymer laminates externally bonded to thermally damaged concrete

“…FRP composites offer several advantages over traditional strengthening materials, including high strength-to-weight ratio, corrosion resistance, ease of application, and minimal changes in structural dimensions (Bisby et al, 2011). The use of FRP laminates has proven effective in the repair and strengthening of thermally or fire-damaged concrete (referred to as “thermally damaged concrete” for brevity) and RC members, including columns (Al-Kamaki et al, 2015; Bisby et al, 2011; Ouyang et al, 2021a, 2021b; Shayanfar et al, 2023; Song et al, 2021; Yaqub and Bailey, 2011) and flexural members such as slabs and beams (Alshannag and Alshenawy, 2020; Haddad et al, 2011; Xu et al, 2019). For example, Haddad et al (2011) conducted an experimental study using carbon FRP (CFRP) and glass FRP (GFRP) laminates to strengthen thermally damaged high-strength RC slabs.…”