Phase O tests - Double Shear Tests of Anchor Rods

Monotonic and cyclic tests of anchor rods were used to further investigate the seismic capacity reductions for anchors in shear. This additional study was conducted to identify the key parameters that affects the seismic behavior of anchors in shear, focusing on steel fracture. Three types of threaded rods, made of ASTM A193 Grade B7, ASTM A307, and ASTM A304 steel, were tested under monotonic shear and cyclic shear. A gap was introduced in between the loading plates, in terms of 1, 2, and 4 times the anchor diameter. The cyclic shear tests indicates that low-cycle fatigue had negligible impact on the behavior of anchor rods made of ASTM A193 Grade B7 and ASTM A307 steel, which are most commonly used for anchor bolts. The impact was significant for the anchors made of ASTM A304 steel, a highly ductile steel. These tests indicated that the seismic capacity reduction observed in the reported shear tests of anchors and the tests in the literature may have been largely caused by progressive concrete damage rather than low-cycle fatigue of steel.