Graphics-assisted tool for the automated numerical modelling of blast-loaded masonry structures - An automated finite-element workflow for constructing pressure–impulse failure diagrams of unreinforced masonry walls

Abstract

Pressure-impulse diagrams provide a compact representation of the failure boundary of a structural element under blast loading, but their construction for masonry walls is expensive, where each point requires a full dynamic finite-element analysis. This thesis develops a methodology and an accompanying graphical tool that automates the construction of pressure-impulse failure boundaries for unreinforced masonry walls. The objective is to establish a reproducible workflow for arbitrary wall configurations. The methodology selects components along three axes. Masonry is represented by a simplified-micro model with bricks modelled by Concrete Damaged Plasticity with rate-dependent hardening, along with mortar joints as cohesive interfaces. The blast load is implemented in two modes: validation mode applies a ConWep load for scenar ios with known charge weight and standoff, and sweep mode applies a single-coefficient exponential pulse parameterised directly by the target peak pressure and impulse. The sweep algorithm is an adaptive Bayesian boundary tracer that combines strategic seed ing, fix-pressure and fix-impulse bisection, and parametric hyperbolic fitting. The methodology is demonstrated on an arbitrary single-wythe unreinforced masonry wall of 1200 × 1155 × 50 mm, with zero-thickness mortar joints, in-plane fixed and out-of-plane pinned supports, and an axial pre-stress. The criterion used for failure is taken at the UFC 3-340-02 transition between the reusable and non-reusable damage states. The sweep identifies nine boundary points in sixty finite-element evaluations across approximately 35 hours of wall-clock time, spanning the impulsive, dynamic, and quasi-static regimes. Fitted hyperbolic curves bracket the pressure asymptote be tween 1.33 and 3.05 kPa depending on parametric form, with the impulse asymptote near 55 kPa·ms. The graphical tool achieves its design goal of making the modelling process accessible without case-by-case manual setup