Parametric modelling of a hybrid timber-earth floor slab for structural and fire safety requirements

Abstract

In recent years earth-based materials have gained increasing interest in the fields of architecture, structures, and building construction due to their broad availability, natural character, and ability to be readily reused in circular and regenerative construction. One recent development from the HORTUS building near Basel, Switzerland involves a standard hybrid floor structure with simple timber beams, an upper three-layer timber panel, and rammed earth located in the cavity space between each timber beam. This work presents a 3D parametric structural model of this timber and earth floor slab module, for use as a preliminary design tool for future projects and broader application. The parametric model is created with Rhino^® and Grasshopper^® software with Python coding, and takes the floor slab loading, floor slab module width and number of beams, and span length as basic input parameters, among others related to materials and fire rating. Optimized beam cross-sections are then computed for a minimal-material timber beam solution that also satisfies estimated fire requirements in an accidental limit state and static and dynamic structural engineering calculations at both the ultimate and serviceability limit states. The parametric model further creates a 3D model of the desired floor slab module using the state-of-the-art COMPAS Timber open-framework software, thereby providing future potential for compatibility with digital fabrication workflows and manufacturing in the longer term.