The effect of cyclic loading on the bond strength of concrete plugs embedded in tubular steel piles

Investigations into the performance of concrete plugs in tubular steel piles under tension, compression and cyclic loading have been conducted at Monash University over the past four years. The work presented in this paper reports on the results of pull out with initial cyclic loading tests carried out on six steel tubes specimens filled with reinforced concrete plugs with variable depths. Test results included the initial cyclic loading, ultimate pull-out forces, slip of concrete plugs, and longitudinal and hoop strains along the piles for some specimens. The tests clearly showed that average bond strength achieved in static pull out and pull out with effect of initial cyclic loading significantly exceeds expectations and it is higher than the results of previous investigations using plugs without reinforcement. The test results also indicated that pre-cyclic loading tests reduced the bond strength due to the significant prior damage to the plug pile interface.