Stress Wave Propagation and Structural Response of Precast Concrete Segmental Columns under Simulated Blast Loads

Although a number of precast concrete segmental columns (PCSC) have been built and developed in recent years owing to their various advantages, the dynamic responses of the column under blast loads are not well investigated. The characteristics of stress wave propagation within the column and their effects on the response and failure of the PCSC are still unknown. Understanding blast load induced stress wave propagation and the subsequent dynamic structural responses of PCSC is essential for blast resistant design and protection of PCSC. In this study the dynamic behaviours of the PCSC under blast loads are numerically investigated by using the explicit finite element software LS-DYNA. The numerical models and modelling techniques are carefully validated by three experimental blast tests from three different studies. The stress wave propagation within the cross-section and along the column height caused by blast loads is examined. The effect of steel tubes in protecting the PCSC from the blast loads is also investigated. It is found that the deformation of the column section under blast loads consists of two main phases, i.e. compression phase and expansion phase, in which failure of the concrete segment mostly occurs in the latter phase. Besides, the use of steel tubes has a marginal influence during the compression phase on the concrete section, but it becomes crucial in the expansion phase that the local failure of concrete segment, i.e. spalling and scabbing, is prevented by the confining effect. Furthermore, confining all concrete segments by steel tubes shifts the response of the PCSC from the local failure of the concrete segment to the global flexural response with fracture of the post-tensioned tendon. The influence of the blast location on the response of the column is also investigated in this study.