The challenge in understanding immense aspects of architectural design process has been the central issue in an attempt to computationally define design process and design knowledge. Relationships between designs and the sources of the ideas used to generate them are extremely complicated to quantify, and to represent in the manner of explicit knowledge and data. Parameters that influence architectural design include a body of knowledge about the subject-matter, requirements of all involved parties, information about prevailing conditions on the site, and information about the traits and trends in the society served by the building. This paper discusses development of knowledge-based representations of architectural design process, particularly focusing on representations of design knowledge and factors in ontological framework. A case study for tall building design is used to demonstrate the representations. Web-based application is presented to exhibit the method for utilization in the schematic design, especially for decision-making process.