Unjustifiably neglected especially in European practice, semi-rigid bolted beam-to-column joints with flange cleats allow great savings in the design, fabrication and erection. With simple stiffening of angle flange cleats and some small additional cost of execution better mechanical behaviour of this type of joint can be obtained. There are several theoretical models for characterization of the behaviour of the flange cleat in bending. Some of them are based on the model of T-stub in tension and some on the model of angle cleat in bending. The differences that are obtained with the application of the existing models are high and to date no systematic evaluation of these models has been implemented. In order to obtain the actual behaviour of this component advanced laboratory testing have been conducted. A detailed description of laboratory testing of four types of flange cleats in bending i.e. of pairs of angle cleats in tension has been given here. In this, original modifications of to date unresearched types of flange cleats with a stiffener have been tested. With the characterisation of F-Delta experimental curves, experimental values of resistance, stiffness and ductility have been obtained for all twelve specimens of flange cleats in bending. The results were used for the comparison and evaluation of the existing models of resistance and stiffness and for the development of models for the evaluation of the stiffened flange cleat behaviour. To characterize the behaviour of stiffened flange cleats, new models that are based on the existing models for standard angle flange cleats have been proposed. The existing and originally developed models for the assessment of resistance and stiffness of the tested types of flange cleats have been evaluated. The adequacy of the proposed stiffener, and the acceptability of the proposed models, is emphasized.

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