Shear Strength and Behavior of Flat Slab Structures Reinforced With Headed Shear Studs

by Thai Xuan Dam

Institution: University of Michigan
Year: 2016
Keywords: punching shear; slab reinforcement ratio; shear studs; shear reinforcement layout; Finite element anaysis; flat plate system; Civil and Environmental Engineering; Engineering
Posted: 02/05/2017
Record ID: 2064885
Full text PDF: http://hdl.handle.net/2027.42/133346


Headed shear studs, or stud rails, are a popular form of shear reinforcement used at slab-column connections. In North America, stud rails are typically placed perpendicular to column faces in a so-called orthogonal (or cruciform) layout to reduce interferences with slab flexural reinforcement. A potential issue with the orthogonal layout of shear studs is that large regions of the slab extending out from the corners of the columns are essentially unreinforced in shear. This issue can be addressed by placing stud rails that project radially out from the corners of the column, referred to as a radial layout. Conflicting results were found from research investigations on the effect of the two shear stud layouts. These conflicts are likely related to the percentage of flexural reinforcement in the slab near the slab-column connection. An experimental program consisting of five full-scale slab-column connections was conducted to study the effect of the layout of stud rails and the percentage of slab flexural reinforcement on the behavior and shear strength of slab-column connections. Significant differences in failure mode were observed in slab-column connections with shear studs arranged in a radial layout compared to those with an orthogonal stud layout. Also, post-yield punching shear failure in slabs with relatively low flexural reinforcement ratios occurred at shear forces lower than the nominal shear strength calculated according to the ACI Building Code. For these slabs, the use of a radial stud layout led to substantially greater ductility compared to a cruciform layout. A minimum percentage of slab flexural reinforcement is proposed so that the nominal shear strength given by the ACI Code for slab-column connections can be reached. Three-dimensional nonlinear finite element analyses were conducted using Abaqus to simulate slab-column connections. The developed models were able to simulate shear strength and behavior of the test specimens with reasonable accuracy. Also, the finite element models were able to accurately reproduce the flexural, shear, and splitting cracks observed in the test specimens Advisors/Committee Members: Wight, James K (committee member), Barber, James R (committee member), McCormick, Jason Paul (committee member), El-Tawil, Sherif (committee member), Parra-Montesinos, Gustavo Jose (committee member).