Parametric 3D modeling in building construction with examples from precast concrete

Buildings are complex products containing relatively large numbers of distinct parts that are collected in multiple assemblies for different design, analysis and production purposes. Modeling buildings in fully parametric 3D computer-aided design (CAD) systems offers numerous benefits in terms of productivity, the ability to rapidly generate design alternatives at different levels and elimination of errors that result from the disparity between different drawings in current practice. However, full realization of these benefits requires specialized functionality, including top-down modeling, objects with functional behavior, the ability to embed contextual design intent, automation of layout and detailing and appropriate management of similar objects. An effective system must provide such functionality while maintaining adequate response times. The requirements, features and performance have been examined as part of specification of a new 3D parametric CAD platform for the North American Precast Concrete Software Consortium (PCSC). They are described and discussed after a review of solid and parametric modeling, with examples from the domain of precast concrete construction.