Modelling Rocking Behaviour Using Physics Engine Simulation

Abstract

The response of a rigid rocking block has been thoroughly studied. From a mathematical modelling standpoint, a pure rocking system is complex, sensitive and sometime chaotic. Because of the complexity, it is generally not practical to develop equation-based models beyond simple three-dimensional rigid blocks or simple idealised structures. Whilst equation-based formulation is valuable and will remain a key method for understanding the fundamental mechanisms behind rocking, a more versatile yet reliable technique is required to model the response of real engineering systems. This study demonstrates the use of physics engine based simulations to model rocking behaviour. Physic engine based simulation is an agent based modelling technique that is sufficiently versatile to simulate complex three-dimensional systems. Importantly, it is also ideologically consistent with fundamental equation-based modelling approaches, such as that of Housner’s simple rocking model. This study simulated the response of 102 free rocking rigid blocks and 96 rigid blocks subjected to sinusoidal motion using Blender (an opensource software with an embedded physics engine), and compared the results against classical numerical integration of Housner’s equation of motion. The results comprehensively validated that Blender can produce results consistent to Housner’s assumption with relatively minimal modelling and computation efforts. As a proof of concept, qualitative results from a masonry wall rocking out-ofplane under base excitation simulation is presented.