The paper is a part of wider research based on the system approach to the problem of modelling and calculations of bolted flange connections. With this approach it is possible to independent consideration of each system's element in order to find the best model of this element. The aim of this study is to develop a model of the single-bolted joint separated from the bolted flange connection. An analysis is conducted for the spider bolt model which is an equivalent model corresponding to the

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... ial bolt model. The key problem in the case of modelling bolts with the spider bolt model is adequate distribution of the preload on the bolt head. Accuracy of modelling bolts using the spider bolt model strongly depends on the way of this distribution. The effect of preload distribution in the spider bolt model on stiffness values of the element fastened in the bolted joint has been examined. The result of actions described in the paper is proposal distribution of the preload on nodes belonging to the bolt head which guarantees the best effects of spider bolt model application.