Knowledge-driven automated prefabricated bridge modeling from natural language using LLM and RAG
摘要
In the design of prefabricated bridges, translating unstructured natural language requirements into standardized Building Information Modeling (BIM) models remains a key efficiency bottleneck. Existing BIM tools lack knowledge-driven alignment between natural language and engineering standards, as well as end-to-end automation from textual instructions to geometric modeling. To tackle these challenges, we propose AutoBIM, a framework that integrates Large Language Models (LLM), Retrieval-Augmented Generation (RAG), and structured prompts to automate the conversion of open-domain instructions into fully compliant BIM models. The core innovation lies in using RAG to ground LLM outputs within a verified knowledge base of standard components, eliminating hallucinations with 100% parameter accuracy and ensuring strict adherence to engineering specifications. Experimental results from a real prefabricated box-girder bridge case show that AutoBIM achieves 100% task success across diverse instructions, completing modeling in approximately 3.5 min—significantly outperforming pure LLM and keyword-based methods. This work demonstrates the potential of LLM–RAG integration for semantics-driven, standardized engineering design and provides a feasible knowledge-driven technical pathway for intelligent BIM modeling in the architecture, engineering, and construction (AEC) industry.