If structures are exposed to accidental loading from seismic action, explosion, impact, fire or other causes, local load-bearing sections may be put wholly or partially out of function. From this perspective, considering tie connections for concrete components in precast structures, it is evident that their ductility when loaded to capacity is essential. Knowledge of the load–deformation relationship will, in many situations, make it possible to check the failure mode of a structure. A large displacement capacity, with the load capacity fully or partially maintained, will increase the possibilities of alternative load paths. In spite of the importance of the choice of suitable tie connections, little research has been carried out in this field.

This Technical Report is based on experimental work carried out at the Chalmers University of Technology in Gothenburg, Sweden. It aims to establish the order of deformation capacity for conventional tie connections as well as to indicate the potential of new types. It provides calculation methods for evaluating the displacement capacity in a specific situation. However, the experimental work so far deals with either comparatively simple or idealised tie connections; the fact that in practice they are often complex indicates that further experimental work is necessary in the future.

Mr Björn Engström (Sweden) prepared this paper for the FIP Commission on Prefabrication, of which he is also a member, and led the above-mentioned research work, which formed part of investigations carried out in Sweden on the theme of progressive collapse. The experimental work was to a great extent conducted by Mr Thomas Pettersson (Sweden), and contributions were also made by Professor Hiroshi Matsushima (Japan).

Mr Engström and Professor K. Cederwall (Sweden) have previously dealt with another important safety aspect on supports for the FIP Commission on Prefabrication, and a paper entitled Effects on the shear capacity of floor slabs due to support fixations was published in the Proceedings, Part I, of the FIP Congress 1978 in London. In that paper, experimental work is reported and recommendations for design are given.

The future research work of the FIP Commission on Prefabrication in this field is planned to be extended, so that a Working Party on Connections and Ties in Precast Structures will be formed, the aim being to prepare a guide to good practice or recommendations.