PLT - 3D Detailing for Hydraulic Structures: Capabilities and Deficiencies

Starting with hand drafting and evolving with the increased use of computers and computer aided design and drafting (CADD) in the early 1980s, production of construction drawings for hydraulic structures has typically been created as two-dimensional (2D) representations of three-dimensional (3D) objects. However, for dams, spillways, gates, and other hydraulic structures that may have complex geometries, 2D CADD has its limitations. Since the late 2000s, building information modeling (BIM) has become heavily used. BIM programs are tailored towards efficient modeling and development of construction drawings for building structures. 2D CADD models can be difficult to produce complex structures.

Designs often progress rapidly throughout a project. Changes, especially late in the design or construction process, can lead to redrawing elements numerous times on multiple different sheets in 2D CADD. 3D modeling can better illustrate more complex or irregular geometries while also improving production of less complex structures. Another benefit of 3D modeling is updating an object one time can apply that change to all occurrences in a drawing set. Modeling structures in 3D accurately improves visualization and communication with owners, reviewers, and contractors. BIM is a great tool for modeling, visualization, and it creates quality details, but it does have its challenges. 3D object-based modeling changes the workflow for drawing production. Producing detail views such as sections and isometrics may only require a few mouse clicks, but annotation poses challenges not observed in 2D CADD. Some issues have workarounds within the software while others do not, which could result in increased production time or adjustments to one’s drafting standards.

Presents the capabilities and challenges of producing construction documents using BIM software, based on examples created using Revit software that include a labyrinth weir, converging chute, stilling basin, and other structures. Lessons learned for addressing design changes, complex geometries, object modeling, annotation issues are presented for the betterment of the dams industry. Better and more efficient designs can lead to safer dams, better clarification of design intent, and overall higher productivity during design and construction.

This paper will benefit engineers, CADD technicians, contractors, owners who operate and maintain their dams, and regulators who review design drawings, whether produced in 2D or 3D, and presents selection considerations. Although this paper focuses on more commonly utilized aspects of 3D versus 2D modeling, capabilities of up to seven dimensions are summarized, adding the dimensions of time, money, sustainability, and facility management.