For many years, the deterioration and corrosion of ferrous materials have been identified as a major problem in Civil Engineering structures. Significant developments in material technology have made it possible to use alternative non-corroding materials such as pultruded fibre reinforced plastics (PFRPS) in construction. In order to improve the design efficiency of PFRP frame structures, the use of semi-rigid design techniques is recommended.The semi-rigid response of a frame connection is characterised by its moment-rotation curve. It is possible to determine the moment-rotation for any configuration by means of experimental testing, but this can be both time-consuming and expensive. An alternative method is to use numerical modelling techniques to analyse the connection behaviour.A two-dimensional finite element model of a PFRP semi-rigid connection is presented. A number of factors, which have a significant effect on the behaviour of the joint, are discussed. These include the modelling of the bolted assembly, the application of prestressing forces and the interface modelling of the contacting surfaces. Results from the finite element investigation compare favourably with measured data from experimental testing. (C) 2001 Elsevier Science B.V. All rights reserved.