Static Behavior of Anchors under Combinations of Tension and Shear Loading

A research project has recently been completed that had the objective of determining how the seismic behavior and strength of anchors (cast-in-place, expansion, and undercut) and their supporting concrete differ from the static behavior. To that end, a research program was carried out on the dynamic behavior of anchors (fasteners) to concrete. The research program comprised four tasks: 1) static and dynamic behavior of single tensile anchors (250 tests); 2) static and dynamic behavior of multiple tensile anchors (179 tests); 3) static and dynamic behavior of near-edge anchors (150 tests); and 4) static and dynamic behavior of multiple-anchor connections (16 tests). The anchors tested were selected based on their reported frequency of use in nuclear power plants in the U.S. Anchors included cast-in-place headed bolts, grouted headed bolts, two wedge-type expansion anchors, one sleeve-type expansion anchor, and two undercut anchors. Loading conditions included tension, shear, and combined tension and shear. Test variables included different concrete strengths and types, loading rate, and the presence of cracks. This paper deals with the static behavior of single and multiple undercut and sleeve anchors placed in uncracked concrete and loaded by combinations of tension and shear. The results are used to draw conclusions regarding force and displacement interaction diagrams for single anchors and the applicability of elastic and plastic theory to the design of multiple-anchor connections to concrete.