Speaker
Description
Waterborne debris impacts in extreme hydrodynamic events are important threats to the structural safety of masonry structures. Recent studies highlighted the fundamental role of high strain rate effects in controlling the structural response of such structures under debris impact loads. Moreover, these studies revealed that the tensile strain rate dependent material response is significantly more influential than the compressive post elastic and elastic responses. This is due to the governing role of tensile cracks of masonry panels at failure. However, the heterogeneous nature of masonry structures, composed of units and mortar layers, requires special attention to the strain rate dependent failure modes at the micro scale, which is not currently discussed in the literature. This paper investigates the different strain rate time histories occurring in units and mortar parts under waterborne debris impact loads on masonry structures. The discussion is made in terms of the speed at which strain rates grow and of maximum strain rates. High-fidelity numerical models are developed using a detailed masonry micromodel with nonlinear and strain rate dependent material properties. The debris impact force is applied by directly modelling the debris body impacting and interacting with the structure. It is found that high strain rate effects are more important in mortar layers as strain rates develop faster and have higher extreme values than in brick parts. These findings lead towards optimised design and modelling strategies for masonry structures under waterborne debris impact loads.
