Mechanical Behavior and Failure Analysis of Masonry Structures Subjected to Dam-Break Flood Loads

Dam‑break floods impose rapidly varying hydrostatic, hydrodynamic and debris‑impact loads on downstream buildings, creating failure conditions that differ markedly from conventional, slowly rising flood levels and that are especially critical for unreinforced masonry systems. This article presents a numerical workflow for evaluating the mechanical behavior and failure of masonry walls under dam‑break loading, and for comparing bare masonry with steel‑retrofitted configurations, as demonstrated on a generic but fully defined example. The protocol begins with the definition of a dam‑break scenario, construction of a two‑dimensional hydraulic model of the downstream valley, and extraction of time histories of water depth and depth‑averaged flow velocity at representative building locations. These hydraulic outputs are converted into time-dependent hydrostatic and hydrodynamic pressures and mapped onto nonlinear finite element models of masonry walls with and without steel frames, braces or anchors. Transient analyses are then used to track out‑of‑plane displacements, cracking and damage indices until one or more collapse criteria are reached. By repeating the coupled hydraulic-structural simulations over multiple dam‑break scenarios and parameter variations, the workflow produces depth- and depth-velocity‑based physical vulnerability curves that quantify expected damage or conditional collapse fraction across the analyzed scenario set for each configuration. The method is designed to be implemented in standard hydraulic and nonlinear structural analysis environments, to be validated against available experimental or analytical benchmarks, and to support performance‑based flood‑risk assessment and comparative evaluation of steel retrofit strategies for masonry building stocks exposed to dam‑break flooding.