Headed stud shear connectors in solid slabs and in slabs with wide ribbed metal deck
This thesis summarizes the results of an experimental investigation of the behaviour of headed stud connectors in push-out specimens with headed studs embedded in solid slabs and in slabs with wide ribbed metal deck oriented parallel to the beam. The experimental investigation involved the testing of 104 push-out specimens and was conducted in three phases. The first phase involved a study of the effects of transverse stud spacing on the shear strength of headed studs in push-out specimens with solid slabs and those with wide ribbed metal decks. The objectives of the second phase were to conduct a parametric study of the behaviour of headed studs in push-out specimens with solid slabs and to propose new equations for predicting the ultimate stud capacity for this case. A similar study involving specimens with wide ribbed metal decks formed the third phase. For specimens with 150 mm solid slabs, there is an increase in the shear capacity of headed studs when the transverse stud spacing is increased from 3 times the stud diameter to 4 times the stud diameter (d) beyond which the strength-transverse stud spacing curve forms a plateau. The percentage increase in stud shear capacity is higher when failure is concrete related than when shank shear of studs is the mode of failure. For specimens featuring 150 mm slabs with wide ribbed metal decks, the shear capacity of headed studs attains a maximum value when the transverse spacing is 3d and decreases when the transverse spacing is increased to 4d beyond which the strength-transverse stud spacing curve forms a plateau. For specimens with solid slabs, there is an increase in the stud shear capacity with the increase in longitudinal stud spacing, up to a transition point, beyond which the strength-longitudinal stud spacing curve forms a plateau. This transition point occurs at a longitudinal stud spacing of approximately 5d when the concrete compressive strength is approximately 25 MPa and at 4.5d when the compressive strength of concrete is over approximately 30 MPa. In general, the failure modes of specimens with closely spaced studs was concrete related. When the stud spacing was increased, the failure mode changed to shank shear of studs. The effect of concrete compressive strength on the shear capacity of studs was found to vary approximately in proportion to the square root of the increase in the compressive strength of concrete. The effect of transverse reinforcement is more pronounced for specimens with concrete related failure than those with shank shear failure of studs. A new equation proposed by the author for predicting the shear capacity of headed studs in solid slabs provides much better correlation to test results than those obtained using CSA and Eurocode 4 provisions. Unlike these code provisions, the proposed equation takes into account the effects of longitudinal and transverse stud spacing, and transverse reinforcement. For the specimens with wide ribbed metal deck, the relationship between longitudinal stud spacing and stud capacity was nonlinear and the strength-longitudinal stud spacing curve did not attain a plateau within the range of longitudinal stud spacings considered. Within the range of the flute widths considered, the deck geometry does not appear to have any significant influence on the stud capacity for specimens with 150 mm slabs as well as for those with 103 mm slabs. The most common failure mode for the specimens with wide ribbed metal decks was concrete shear plane failure. A new equation proposed by the author for predicting the shear capacity of studs in wide ribbed metal deck provides better correlation to test results than those obtained using CSA and Eurocode provisions.