Refinement of a Design-Oriented Stress–Strain Model for FRP-Confined Concrete

Abstract

This paper presents the results of a recent study conducted to refine the designoriented stress-strain model originally proposed by Lam and Teng for FRP-confined concrete under axial compression. More accurate expressions for the ultimate axial strain and the compressive strength are proposed for use in this model. These new expressions are based on results from recent tests conducted by the authors' group under well-defined conditions and on results from a parametric study using an accurate analysis-oriented stress-strain model for FRP-confined concrete. They allow the effects of confinement stiffness and the jacket strain capacity to be separately reflected and accounts for the effect of confinement stiffness explicitly instead of having it reflected only through the confinement ratio. The new expressions can be easily incorporated into Lam and Teng's model for more accurate predictions. Based on these new expressions, two modified versions of Lam and Teng's model are presented. The first version involves only the updating of the ultimate axial strain and compressive strength equations. The second version caters for stress-strain curves with a descending branch, which is not covered by the original model. This is the Pre-Published Version.

Axial compressive behavior of FRP-confined concrete: Experimental test database and a new design-oriented model

“…Average hoop rupture strain reduction factor (k ε ) with FRP type and confinement technique Table 4. Lam and Teng [3] Wu and Zhou [52] Wu and Wang [51] Al-Salloum and Siddiqui [45] Wei and Wu [50] Realfonzo and Napoli [7] Bisby et al [5] Jiang and Teng [32] AAE in predictions of strength enhancement ratio (f' cc /f' co ) Wei and Wu [50] Binici [46] Jiang and Teng [42] Youssef et al [53] Teng et al [49] Fahmy and Wu [47] Teng et al [48] De Lorenzis and Tepfers [4] AAE in predictions of strain enhancement ratio (ε cu /ε co ) …”

A Design-Oriented Combined Model (7 MPa to 190 MPa) for FRP-Confined Circular Short Columns

“…While the prediction performance of some models are restricted concerning range [22], some of those models are also capable of reasonably predicting wider data ranges [5,33,41]. Specific strength models generally overestimate the ultimate strengths (f cc ) for f co > 70 MPa [1,5,22,33,41,43,44,50,55] or for f co < 20 MPa [1,22,44], however, some models having a good accuracy for all the data ranges are also available [45]. Herein, the performance details of those strength models will not be mentioned again in detail.…”

“…The prediction capabilities of specific strain models [2,32,33,[38][39][40][41]43,44,46,73] are investigated. Following this assessment, the empirical models of this study are introduced to predict the ultimate strains (ε cu ) with high accuracy.…”

“…The lower and upper parts of this line indicate conservative and unconservative strain estimations, respectively. The specific models [2,32,33,[38][39][40][41]43,44,46,73] were investigated with regard to the range of database in this study. However, it should be mentioned that those models tend to significantly overestimate the strain capacity, at or over about f co = 100 MPa.…”

Comparative Study of CFRP-Confined CFST Stub Columns under Axial Compression

“…In many engineering fields, the CFRP-metal composite tanks or tubes have been used widely, such as gas tank used in motor vehicle and pipeline system for transporting high pressure gas or liquid used in municipal engineering or chemical engineering. CFRP materials, as external jackets for the confinement of reinforced concrete columns, can enhance strength and ductility [3][4][5][6].…”