Effect of contact plasticity on the seismic response of a 7-duct bundle immersed in fluid

Abstract

In the reactor core, the ducts, submerged under fluid, are closely packed. As a result, the collision between ducts is inevitable during the seismic load. Understanding seismic response of the ducts needs to consider both the collision between ducts and the inertial effect from the surrounding fluid. For the collision model, we proposed a nonlinear contact model from a full scale simulation to consider the plastic effect during collision; For the fluid effect, we built an acoustic-structural model to obtain the added mass coefficient depending on the duct's location. Next, we integrated the effects from plastic collision and the fluid inertia into a beam model to study the seismic response of a 7-duct bundle, and then discussed the plastic effect on the contact forces, contact durations and duct acceleration. Results show that although contact plasticity hardly affects the ducts’ motion, it has a noticeable effect on both contact force and contact energy dissipation. In addition, our result shows that the contact duration for one typical type of collisions tends to be constant.