Collapse simulation of reinforced concrete moment frames considering impact actions among blocks

• Impulse-based impact models for collisions between fractured components are proposed.
• A DEM-based collapse simulation system with impact models is developed for RC frames.
• Visual collapse simulation of two frames in an earthquake and controlled explosion.
• Collapse mechanism, including impacts and debris distribution, is presented.
• Proposed simulation system can facilitate collapse simulation of RC frames.

A simulation system based on the Discrete Element Method (DEM) was developed to model the collapse behavior of reinforced concrete (RC) moment frame structures subjected to seismic loads or explosions. This system mainly consists of two parts: a numerical analysis part that simulates the collapse process of RC moment frame structures quantitatively, and a visualization system that vividly shows the dynamic responses obtained from the numerical analysis. Using this system, the whole damage process of a structure can be numerically analyzed and visually simulated. Consequently, the collapse mode, mechanism and duration and the distribution of the debris after the collapse can be obtained. The numerical analysis is based on the DEM, in which the element shape is assumed to be cuboid, and the elements are connected by dummy concrete springs and steel springs. The impact actions among elements, particularly after breaking of the connecting springs, are taken into account with the application of impulse-based impact models, which are derived from the results of the experiments and the numerical tests. Finally, two examples, including a frame building demolished by a controlled explosion and a scaled model structure of an RC moment frame subject to an earthquake, are presented to verify the impact models and simulation system and to reveal the collapse mechanism of RC moment frame structures subjected to abnormal loadings.