Experimental Investigation of Anchor Group Effects on Concrete Breakout Strength Within Fiber Reinforced Concrete

摘要

This research investigates the effect of anchor groups on concrete breakout strength within steel fiber reinforced concrete (SFRC) under tension load. High strength steel headed studs (F1554 Grade 105) in grouping action were cast-in-place within concrete specimens of different amounts of steel fibers. Four types of concrete mix designs were produced in the lab by using different amounts of steel fibers (0%, 0.5%, 1%, and 1.5%) by volume fraction of the mixture. The physical properties of steel fibers reinforced concrete were calculated through testing of specimens at the Civil Engineering Laboratory Building (CELB). In total, 12 cylinder specimens of 4-inch diameter and 8-inch height for compressive strength, 12 cylinder specimens of 6-inch diameter and 12-inch height for split tensile test, 12 beam specimens of 6*6*20 inch for modulus of rupture and flexural behavior. 4 concrete beams of 54*18*10 inch were cast-in-place with 12 sets of anchor groups were installed and tested after 28 days of curing. Embedment depth and distance between anchors for all group sets are kept constant. The effective embedment depth and the spacing between two anchors in grouping action are specified as per ACI 318-19. The experiments revealed that the increase of the amount of the steel fiber fraction increases the concrete breakout strength of anchor groups in tension by 43.33%, 73.42%, and 81.1% for 0.5%, 1.0%, and 1.5% volume fraction of steel fibers respectively. The research shows that the diameter of the concrete failure cone was reduced by increasing steel fibers. The failure angle increased by 14.6%, 48.5%, and 70% for 0.5%, 1.0%, and 1.5%. The concrete breakout strengths for anchor groups were compared with single anchors were tested at the same conditions. The anchors group effect reduces the concrete breakout strength by (19.45%, 16.8%, 15.7%, and 14%) for (0.0, 0.5, 1.0, and 1.5%) steel fiber compared with single anchor. Concrete compressive strength increased by (9.5%, 25.5%, and 17.5%) for (0.5%, 1%, and 1.5%) steel fibers respectively. The split tensile strength increased by (20.5%, 32.63%, and 35.35%) for (0.5%, 1%, and 1.5%) steel fibers and the flexural of concrete increased also by (3.7%, 9.8%, and 16.4%). Finally compare the experimental results of the concrete breakout strength with modified Concrete Capacity Design Method (CCD).