On the fracture behavior of thin-walled SFRC roof elements

Several experimental investigations aimed at the analysis of the structural behaviour of thin walled steel fibre reinforced elements highlighted the effectiveness of design rules suggested in standards, recently proposed for the prediction of serviceability and ultimate limit states, but also a significant interaction between the longitudinal and the crosswise bending of such elements at failure. The interaction due to second order effects is caused by both the open cross-section shape of the prefabricated elements and the reduced thickness of the profiles. The tests correspond to a large scale tests of a strip plate 1 m wide and 30 m long subjected to an eccentric tension. The shape loss of the cross section drastically anticipated the longitudinal bending collapse. A model based on the equilibrium of a segment assumed perfectly stiff in the cross section plane and a Finite Element approach are compared to explain the onset of the collapse. Very precious indications are pointed out in order to realize what happens in this large scale fracture mechanical test.