Donny YULIANTO
Study on Behavior and Strength of Lying Stud in the Ultimate Limit State
Masatsugu NAGAI
Recently, Cost down measures on Construction of Steel Bridge is increasing in number. One of the alternative methods is Composite Bridges. Composite Bridge which is optimizing the merit of Steel and Concrete materials has shear connector as a member for transferring its composite action. There are various types of shear connector, and among them, Headed-Stud is the standard type, applied in Japan Road-Bridges.
As the development of Composite Bridges continuously held, Double Composite Bridge is proposed. Double Composite Bridge is thought to be a promising type for long span bridge. This is made possible with the casting of lower slab at the mid-span support, which prevents local-buckling of lower flange.
Lying Stud is proposed as the shear connector for transferring horizontal shear force between lower slab and lower flange. Both Lying Stud and Vertical Stud transfer horizontal shear force, but the positioning of Lying Stud, cause shear-actions in the slab-thickness direction. Based on previous research held by Kuhlman, these shear-actions are found to extend as splitting-actions, which cause cleavage cracks and resulting in the splitting of the slab. Kuhlman proposed an empirical equation for predicting strength of lying stud, which considers these splitting actions.
In this study, push-out tests considering 2 types of lower slab are performed, and the ultimate strengths are compared to values from various Shear Connection Equations.
The results from this Study could be concluded as below:
1.Ultimate Strength Characteristics of 1-row and 2-row of studs (Case 1 and Case 2).
It is found that the Ultimate Strength of 1-row and 2-row of studs are mostly identical.
2.Fit in of Kuhlman Equation in Predicting Ultimate Strength of 1-row and 2-row of Studs.
Kuhlman equation values were found approximately 1.25 times the Experiment results. Since Kuhlman Equation has a partial factor of 1.25, Kuhlman Equation shows a well fit in. Meanwhile, approximately 10% safe side could be reached by applying this 1.25 factor to Chang Equation.
3.From the Load-Slip Relationship, during the increment of loading, rising and lowering of Load were found. These phenomenons are thought as the result of large amount of reinforcement steel and stirrup on the test specimen.
4.Comparison of All-lying stud and Mixed-Stud Test Specimen(Case 3 and Case 4)
All-Lying Stud and Mixed-Stud Test Specimen showed almost the same strength per stud.
5.Comparison of Case 1&2 and Case 3&4
The Strength of Case 3&4 are nearly 40% of Case 1&2. The presence of Lower Flange and the difference of Stirrup Hook are predicted to be the reason, but this study did not reach the thorough cause folding.
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