Behaviour of Headed Stud Connectors in Composite Beams with Very Deep Profiled Sheeting

Lack of design rules and no past research on the behaviour of composite beams with steel decks deeper than 80 mm is a major knowledge gap. Thus, this research provides fundamental information on the behaviour of headed stud connectors with narrow and very deep decks. After a series of extensive validation, a vast number of 3-D push-off tests are modelled using ABAQUS/Explicit package. Both secondary and primary composite beam systems are investigated. Critical examination is conducted on the existing design equations to assess their accuracy in predicting the shear stud capacity with the use of narrow and very deep decks.
The numerical analysis regarding the secondary composite beams showed that the shear stud capacity with narrow and very deep decks (i.e. 100 and 146 mm deep) was almost 65% of that obtained from the traditional steel decks (60-80 mm deep). The shear stud capacity was mainly affected by the concrete embedded within ribs. Reinforcing that area by a unique wire-mesh bars layout, which has not been investigated before, led the load bearing capacity to increase by 24%. For the primary composite beams, the numerical analysis indicated that the correlation between very deep decks and traditional ones regarding the shear stud capacity can not be represented through the rib deck geometry as it was believed in the past. A new concept was introduced to more accurately explain that correlation. This was through the effective cross-sectional area of concrete.
The existing design equations, when validated, did not account for narrow and very deep decks. As a result, a big discrepancy up to 50% was noticed between the predicted strengths and FE results in some cases, especially among EC4 and ANSI/AISC provisions. This necessitated to introduce more effective formulae. The developed equations regarding the secondary composite beams covered for the first time a wide range of ribbed geometries including narrow and very deep decks. For the primary composite beams, the correlation between different types of decks was established in the new equations through the effective cross-sectional area of concrete. The reliability of the new equations was proven against many previous experiments. The accuracy in results remained within ±10%. Besides the accuracy, the new equations are easy to use. This will help the designers to directly apply these equations in the practice.