Effect of bending test setup on the structural stability of I-shape pultruded FRP profiles using variable step size FE analysis

Abstract

AbstractDespite the widespread use of pultruded Fibre-reinforced Polymers (FRP) profiles, there is still a lack of standardised guidelines for the design of bending test setups on the structural-size level to match the structural stability demands of real applications in construction. This study investigates and compares the structural instability failure modes of lateral-torsional buckling, local buckling, and web crippling of I-shape pultruded FRP profiles under three-point and four-point bending. A novel modelling approach capable of capturing the longitudinal and sectional instabilities was established and verified against published experimental data and against the theory. The validated modelling approach was used to perform parametric studies on the bending test setup parameters, namely the span-to-depth ratio L/d and shear span-to-depth ratio a/d. The effect of these parameters on the failure modes and their thresholds was investigated and their interactions were characterised. Guidelines and recommendations were proposed for consideration when designing test setups and span lengths of I-shape pultruded FRP beams to widen the use of these profiles with more confidence in broader structural applications.

Keywords

• I-shape pultruded GFRP beam
• lateral-torsional buckling
• local buckling
• web crippling
• bending test setup