EULER BUCKLING OF PARTIALLY STIFFENED PULTRUDED GRP COLUMNS: A COMPARISON OF SHELL FINITE ELEMENT AND BEAM-COLUMN MODEL PREDICTIONS

Abstract

A two-dimensional shell finite element (FE) model and a one-dimensional beamcolumn model are presented for the global (Euler) buckling analysis of partially stiffened pultruded GRP (Glass Reinforced Plastic) WF (Wide Flange) columns subjected to uniform uniaxial compression. By comparison with the buckling loads predicted with the two-dimensional FE model, it is shown that the beam-column model gives accurate predictions of the global buckling loads of simply supported and clamped columns partially stiffened with Type 1 and Type 2 GRP and CFRP (Carbon Fibre Reinforced Plastic) stiffeners. The results obtained also show that Type 1 stiffeners are more effective in raising the buckling load for simply supported columns and, moreover, that there is little benefit in stiffening more than three-quarters of the length of the column. However, for columns with clamped ends both types of stiffener produce similar increases in the buckling load and the greatest increase in the buckling load occurs when the column is stiffened over the whole of its length. Finally, and despite its accuracy, it is shown that the beam-column model is likely to be of limited use for columns with CFRP stiffeners which extend over their whole length, because local or combined mode rather than global buckling occurs for practical column lengths of 3 - 3.5m.