Experimental study on tubular K-joints under impact loadings

• Local plastic deformation is mainly concentrated on the intersection part.
• Unstiffened K-joints suffered dramatic indentation.
• Ring stiffeners sufficiently limited the local indentation.
• Ring stiffeners significantly improved the K-joints impact resistance.

This paper experimentally examines the behaviour of tubular K-joints subjected to impact loadings. An experimental programme involved two tests on unstiffened tubular K-joints under different impact energies and one on stiffened configuration is carried out through a high-performance drop hammer machine. The dynamic responses of three tubular K-joints are described and discussed with emphasis on the effect of impact energy and internal stiffeners. Based on the experimental results, the key behavioural patterns including the development of impact force, deformation and strain, as well as failure modes are identified, and impact mechanism is also investigated. It is shown that the local indentation at the impacted area of the chord is the main plastic deformation of tubular K-joints under impact, and higher applied impact energy results in larger plasticity. Moreover, the presence of internal ring stiffeners significantly improves the impact resistance of tubular K-joints.