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The capacity of headed stud anchors installed in corner applications / Susan L. Caluwe Lasecki.

by Lasecki, Susan L. Caluwe

Anchorage (Structural engineering) -- Testing.

Reinforced concrete construction

101 leaves : ill. ; 29 cm.

Thesis advisor: Dr. John Zachar.

Committee members: Dr. Mahmoud Maamouri, Christopher Raebel.

Introduction -- Literature review: historical and current practices -- Experimental program -- Analysis -- Conclusions and recommendations -- Appendix A: Test specimen configurations -- B: Photographs of specimens during testing -- C: Theoretical calculations -- D: Equation development.

Decades of research and testing have been performed to determine the capacity of headed stud anchors in tension and shear loading. Additional studies have been made on the capacity of these anchors in combined loading. All of these studies have investigated headed stud anchors that have been installed normal to the face of the loaded concrete surface.

The purpose of the investigation was to determine the capacity of headed stud anchors cast into concrete at an edge where the anchor is at a forty-five degree angle. This type of installation is commonly utilized in many cast-in-place, precast and tilt-up applications. Equations which represent the observed capacities will be developed and proposed for use in future design conditions.

Four types of tests were performed to determine the capacities of the headed stud anchors. All of the headed stud test specimens consisted of 1/2" dia. x 4" long headed studs welded to a 3"x3"x5/16" steel angle at a forty-five degree angle. The first test type consisted of a single stud, the second type of test consisted of two studs spaced at 5" c/c, and the third test type consisted of two studs spaced at 9" c/c. The fourth test type was identical to the second test type except that confinement steel was added. The test specimens were each cast into an 8" thick slab with a center recess. Two slabs were cast; each with eight test specimens, four on each side of the center recess. A 3/8" thick steel plate was welded onto each of the steel angles. At the time of the test, a steel clevis was secured through the hole in this plate. A hydraulic ram was connected to a 3/4" dia. rod which was screwed into the clevis. The hydraulic ram was supported by a steel frame. One of the columns of the steel frame was located within the trough and the other was located to the outside of the projected failure area of the concrete around the headed stud. The hydraulic ram was used to then apply a vertical force on the test specimens. The maximum breakout strength was recorded and the failure areas were measured and documented.

The observed concrete breakout failure surfaces were similar to those documented in tension tests of headed studs near a free edge of concrete. The failure cones closely represented the 35 degree failure cone used in current design standards. The capacity of the single stud test was almost precisely one half of the test values of the two studs spaced at 9" c/c. Studs spaced greater than twice the effective length of the stud have the capacity of a single stud multiplied by the total number of studs used.

The ACI 318-05 and PCI Design Handbook - Sixth edition equations both provide an acceptable representation of the stud behavior, provided that the equations are applied properly. Proper application of these equations included correct determination of the effective embedment and the application of the eccentric load factor. New empirical equations were also derived from the actual test results which more closely represent the actual capacities of the connections. The use of these equations may be limited since the testing range was not broad enough to confirm their accuracy in conditions with longer or larger headed studs.

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