Terrain-aware BIM Construction Planning for PrefabricatedBuildings in Complex Mountainous Sites: Method and SimulationValidation

Prefabricated construction in mountainous cities requires coordinated planning of component delivery, temporary storage, crane lifting and assembly under terrain-constrained site conditions. Existing BIM-based planning studies support construction visualization, site layout and logistics optimization, but they seldom evaluate road grade, terrain slope, storage fragmentation and crane-platform usability together at the component level. This study proposes a terrain-aware BIM construction-planning method for prefabricated buildings in complex mountainous sites. The method links IFC-level component semantics with terrain, road, storage, crane and assembly-sequence constraints, and evaluates planning feasibility through a reproducible simulation protocol. A three-storey prefabricated building model with 315 components is tested across five controlled terrain scenarios and one public DEM/OSM-derived proxy scenario. Compared with conventional BIM planning, distance-based BIM logistics and resource-aware BIM logistics, the proposed method achieves the highest mean feasibility index, increasing it to 0.897. Ablation and weight-sensitivity analyses show that sequence and storage constraints contribute most strongly, while Monte Carlo perturbation confirms the robustness of the main comparative conclusion.