Failure analysis of hollow-core slabs tested in shear

G. Bertagnoli, Politecnico di Torino, Italy 
G. Mancini, Politecnico di Torino, Italy 

Many experimental campaigns on hollow core slabs put into evidence critical shear behaviour of such structures. Widespread perplexities on the actual shear resistance of such members took place in the scientific community when the results of these experimental campaigns were published. As a first result the model proposed in the Model Code 90 and in the Eurocode to evaluate the uncracked shear capacity of prestressed elements was supposed to overestimate the real ultimate strength of the members. A more careful interpretation of the shear design of such structures is presented in this paper and shows that there is no safety risk if these slabs are designed with care. The ultimate behaviour of hollow core slabs mainly subjected to shear actions is related to many different phenomena such as prestressing dispersion, anchorage of prestressing strands, cracking bending moment and, of course, shear resistance. The mutual interaction of such phenomena asks for a multi-criteria design approach which is presented in the following and which gives very good results when compared to experimental campaigns output.