## HEADED STUD SHEAR CONNECTORS IN FULL-SIZE COMPOSITE BEAMS WITH WIDE RIBBED METAL DECK

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##### Date

1998-09##### Author

Wu, Hang

##### Type

Thesis##### Degree Level

Masters##### Abstract

This thesis summarizes the results of an experimental investigation of the behavior of headed stud shear connectors embedded in slabs with wide ribbed metal deck oriented parallel to the beam. The test program involved the testing of 60 push-out specimens and 4 full-size beam specimens. The main objectives of this investigation were to evaluate the reliability of existing provisions for headed stud connectors in composite beams with wide ribbed metal deck placed parallel to the beam and, if necessary, to develop a new equation which will provide more. accurate results.
Test results indicated that for the push-out specimens with wide ribbed metal deck, the CSA provisions overestimate the observed connector strength. The average predicted strength was approximately 33% higher than the average observed value. Moreover, the coefficient of variation was found to be approximately 61%. The corresponding values for Eurocode 4 were 10% and 19%, respectively.
The test results indicated an increase of 17 % in the shear strength per stud when the longitudinal stud spacing was changed from 3 to 8 times the stud diameter. The longitudinal stud spacing greatly influences the failure mode of push-out specimens. In general, the failure modes of specimens with closely spaced studs were concrete related. As the stud spacing was increased, the failure mode changed to shank shear of the headed studs. The maximum strength per stud is realized when the stud fails due to shank shear.
The stud shear strength is also affected by a change in the transverse stud spacing, although not to the same extent as that of longitudinal stud spacing. As the transverse stud spacing was varied from 4 to 6 times the stud diameter, the maximum variation of the stud strength was about 7.6%. The optimum transverse stud spacing was found to be 0.53 times the average width of the deck flute.
The observed ultimate load per stud was found to increase as the width to height ratio of the metal deck was increased. The strength gain was approximately 20% as the deck ratio was increased from 1.58 to 3.32. The load per stud increased by 17% as the concrete compressive strength was increased from 32.7 MPa to 42.1 MPa. The increase in the strength of concrete tends to change the failure mechanism from concrete related failures to stud shank shear failure.
This investigation resulted in the development of a new equation for predicting the shear strength for headed studs embedded in composite beams with wide ribbed metal deck. The proposed equation provides much better correlation to test results than that of CSA and Eurocode 4 provisions. The average absolute difference between the observed values and those predicted by the proposed equation was found to be approximately 2.90%, compared to 32.55% and 10.30% for CSA and Eurocode 4, respectively. The coefficient of variation was estimated to be 3.5%. The better results may be attributed to the fact that the proposed equation takes into account, not only
the longitudinal stud spacing, concrete strength and width to height ratio of the metal deck, but also the transverse stud spacing.
A simplified version of the proposed equation was also found to be more accurate than CSA and Eurocode provisions. The average absolute difference between the observed values and those predicted by the simplified equation was found to be approximately 5.50%. The coefficient of variation was 7.6%. Because of the simplicity of the approximate equation and only slightly lower accuracy, this equation is recommended for design purposes.
The experimentally determined ultimate flexural capacities of the four full-size beam specimens agreed very well with the predicted values based on the proposed equations. The average absolute difference between the observed values and those predicted by the original version was found to be approximately 2.77%. The coefficient of variation was estimated to be 2.7%. The current CSA provisions for predicting the vertical deflection of a composite beam was found to provide accurate results.