Behaviour of glass FRP composite tubes under repeated impact for piling application

摘要: Fibre composites have been a viable option in replacing traditional pile materials such as concrete, steel and timber harsh environmental conditions. On the other hand, emergence of fibre reinforced polymer (FRP) composite tubes structural component their corrosion-resistant characteristics made these potential piling application. Driving piles, however, requires more careful consideration due to relatively low stiffness thin walls. The possibility damaging during process impact driving is always concern. Research has therefore focused understanding behaviour order for them be safely effectively driven into ground. This study investigated subjected by repeated axial impact. effects event (incident energy number impact) on instantaneous response residual properties were examined. Tubes glass/vinyl ester, glass/polyester, glass/epoxy different cross sections considered. was experimentally analytically investigated. An experimental square tube conducted. result showed that dominant failure mode tube repeatedly impacted characterised progressive crushing at upper end. This manifested inter intra laminar cracking glass ruptures with simultaneous development splits along its corners. It found drop mass velocity (or height) pronounced the collapse lower incident energies. Their effects, gradually decrease higher also indicated incident energy major damage factor impacts. contrary, impacts becomes key reason soon value decreases. The factors level energy, repetitions, impactor (post-impact) properties were investigation revealed significantly influenced strength degradation tubes. In contrast, modulus less affected since brought localised most cases. maximum reduction on moduli roughly 5%. other hand, strengths degraded up 10%. flexural severely than compressive tensile strengths. fact matrix both contributed degradation. Moreover, presence cracks or delamination lead an increase buckling instability test, resulting much compared comparison sourced locations height reduction varied with location. decreased when location from top increased. influence of impact concentrated only region closer point. Finally, theoretical prediction using basic principle performed gain additional evolution model verified through 100 mm pultruded tube. applied from vinyl ester/polyester/epoxy fibres. results proposed agreed well each other. variation 10% indicating predicted reasonably loading. energies describing cycle, high endurance fatigue regions are largely dependent corresponding critical Ec. Ec values, range characterising regions. curves Ec) tubes made materials. Similarly, circular greater values comparable rectangular From this study, improved FRP under can achieved. information provided will help developing efficient techniques guidelines piles.