In this paper, an innovative sustainable semi-rigid beam-to-column composite joint with deconstructable bolted shear connectors is modelled by using the general purpose software ABAQUS. The structural mechanics of this joint considered in the paper requires careful consideration; in order to capture the response accurately using computational techniques as the interactions of the various components is complex. Three test specimens having sustainable and deconstructable semi-rigid beam-to-column joints have been tested and the results are used for validation of the finite element model. Precast “green concrete” (GC) slabs having reduced emissions during their manufacture were attached compositely to the steel beam via pre-tensioned bolted shear connectors, with the composite beam being connected to H-section columns a using flush end plate with two rows of bolts. The numerical model simulates the composite beam-to-column connection under hogging moment and includes the non-linear material properties of all constitutive materials of the composite joint. The experimental testing was full-sized, with all the components being of the same size as would be met in practice. For validation of the computational procedure, the results of the numerical modelling are compared in the paper with the experimental results, with good agreement being demonstrated.