Integrating spatial and structural considerations in floor plan transformations of historic masonry buildings

Adaptive reuse of historic masonry buildings offers potential to convert vacant structures into multi-family housing while preserving cultural heritage and reducing construction and demolition (C&D) impacts. However, how can spatial reconfiguration and structural stability be computationally coordinated to support early-stage adaptive reuse decisions? This paper introduces a-ARCH, a computational framework that integrates an interactive spatial layout tool for apartment allocation, daylight, and circulation with a multi-objective structural optimization minimizing static eccentricity and C&D costs. The framework is evaluated through sequential and parallel workflows that either couple structural optimization to a spatial solution or compare independently generated spatial and structural alternatives. Results show that comparable structural performance can emerge from different intervention strategies, revealing trade-offs between coordination and design exploration. These findings support architects and structural engineers in performance-informed reuse and motivate future extensions towards broader typologies and sustainability-driven integration.