The simulation of the welding process by means of continuum mechanics models has a very high cost both in input data preparation time and in computing time required for the integration of the complex thermoelastoplastic equations involved in solids with temperature dependent properties. For this reason, the plates in this study will be visualized as formed by a certain number of bars that can carry out elastoplastic behaviour and having temperature dependent properties. The thermal loads are simulated by analytical singular solutions, the thermomechanical problem being solved by means of an incremental algorithm of high efficiency. An excellent agreement has been found between the results numerically predicted and those previously obtained with an experimental technique and the Finite Element Method. Finally, the one-dimensional model developed here is used to predict the effects of a local heat treatment on the residual stresses originated by the welding. The versatility and rapidity of the use of this model makes it specially suitable to be used as a tool to select among different stress relieving procedures.