Title: Evaluation of Concrete Anchorage for Rail Direct Fixation Fastener
Author(s): Arthur de O. Lima, J. Riley Edwards, Marcus S. Dersch
Publication: Structural Journal
Appears on pages(s):
Keywords: concrete anchorage; direct fixation rail fastening; adhesive; female insert; pullout strength; shear strength; threaded rod
Laboratory experiments were conducted to quantify the structural capacity of two concrete anchorage systems employed in rail transit direct fixation track systems (i.e., threaded rod and female insert). Laboratory results were compared with both revenue service loading demands and ACI 318-14 calculated design capacity. The experimental results identified the controlling failure modes in tension as adhesive failure in threaded rods and a combination of splitting and insert thread failure in female insert connections. Concrete breakout is the controlling failure mode for both systems in shear. These findings demonstrate agreement between design calculations and laboratory experimentation. Laboratory capacities were measured at 46,000 lb. and 53,000 lb. [204 kN and 235 kN] in tension, and 22,400 lb. and 18,500 lb. [100 kN and 82 kN] in shear for threaded rod and female inserts, respectively. For threaded rods, the magnitude of laboratory failure capacities is between 2.3 and 21.3 times larger than the calculated ACI design capacity. Although improvements to the direct fixation system’s anchorage capacity are possible through design modifications, the current capacity is adequate for the representative heavy rail transit service environment studied.