Numerical investigation on strength of CFRST composite truss girder

CFRST composite truss girders consist of a CFRST truss and a concrete slab. The failure mechanism and strength of the girder were observed to be different under various failure modes. To investigate the strength of the girder under different loading conditions and parameter combinations, numerical simulations were carried out and validated against existing experiments. The axial force distribution of the girder was found to be similar to the pin-jointed truss model when the concrete slab and the chord were considered a unified component of the composite top chord. Three distinct failure modes were identified, including composite top chord failure mode, brace and joint failure mode, and bottom chord failure mode. The failure mechanism of each failure mode was analyzed, and a design method for the girder’s strength was proposed. The proposed method was validated through numerical analysis and compared with other existing methods. The results showed that the method can accurately predict the strength of the girder under different failure modes while maintaining reasonable safety margins.