Development of improved shear connection rules in composite beams (DISCCO) : final report

This Final Report describes the technical activities carried out under this RFCS contract RFSR CT 2012-00030 which is concerned with developing new rules for the partial shear connection of composite beams. Based on a comprehensive series of push tests on deck profiles of 56 to 80 mm height with 19 mm and 22 mm diameter shear connectors, a proposed standard for the push-out test regime has been prepared which permits use of a transverse loading of 5% of the applied shear load. Ten short span beam tests were performed in order to verify that plastic analysis principles may be used for beams with low degrees of shear connection using shear connector resistances obtained from the push tests. A 15.3 m span composite cellular beam with 36% degree of shear connection was tested in order to examine the extreme case of partial shear connection and it was found that end slips up to 20 mm could be developed at the plastic bending resistance of the composite beam for the particular degree of shear connection. An 11.2 m span composite asymmetric beam with 33% degree of shear connection was also tested, and again the failure load exactly matched the predicted bending capacity to Eurocode 4. As the final part of the testing programme, a 10 m x 4 m floor plate consisting of 9 beams and 6 columns was tested to investigate the interaction effects between the secondary and primary beams and also the effect of the reinforcement around the shear connectors at edge beams. Numerical studies with regard to modelling of composite beams were used for predictions related to the short span and long span beam tests. The numerical analyses also extended to the local behaviour of the shear connectors particularly when affected by concrete cracking and high strains due to concrete crushing. Studies on the relaxation in shear connection rules for composite beams that are partially utilised in bending and for cellular beams have been performed which have led to easy to use results.