Welcome to the Cast-in-Place NBIMS website
Overview
This project will take the first major step in realizing interoperability standards for reinforced concrete construction in buildings. The process for developing such standards is spelled out in the US National BIM Standard. Activities are mapped according to the roles involved in various data exchanges and the lifecycle stage of the project. Exchanges between these activities are documented. Needed project data exchanges are then specified in terms of the information content of the exchanges. These exchange requirements become the specification for information exchanges specified in IFC and later implemented by software companies. These requirements are called by the community Information Delivery Manual (IDM). The requirements may later be used to define a set of flexibly configured exchanges, adapted to different needs. The Information Delivery Manual for Reinforced Concrete will be the major product for this effort.
What is an SEM?
An Short Introduction to Semantic Exchange Modules
Chuck Eastman, Manu Venugopal, Rafael Sacks – Georgia Tech and Technion
Context: The Industry Foundation Classes Schema (IFC) has become recognized de facto standard for interoperability in the AEC/FM industry. IFC is a rich yet redundant schema providing multiple ways to represent information. The 'Model View' approach has been identified as the needed answer for more precisely specifying the contents in a given exchange. The National BIM Standard (NBIMS) was developed in part to address this need.
Many industry and research groups are developing model views for varying aspects of the AECO realm, using the NBIMS. However, only a few exchanges have been defined and implemented thus far. The most visible and important exchange requirements are contractually specified handovers, such as contract documentation at bid time and operations handover when construction is complete. Model views are rigid in their contents and work well when the requirements can be fixed long ahead of time. They are too rigid for problem-solving workflows within a project, where needs quickly vary to support collaboration. There are other limitations. The current approach to MVDs require intensive efforts on the part of users, who using their experience, must specify and agree on the content of exchanges for use far into the future. In reality, the needs often vary case-by-case and the specifiers must normalize these varied needs to a fixed set of content. After the domain users specify the needed exchange content intuitively, software vendors must code and test the numerous model view exchanges, eventually for every domain within AEC/FM that their software supports. Methods for development of model views, while organizationally defined, are not rigorous logically and have limited tools to support the work.
SEM's Contribution: The idea of modularization of model views has been around for awhile. SEMs makes them partial implementable units. The idea of Semantic Exchange Modules (SEM) is to provide a layer of specificity above the base level of IFC. The modules are organized based on clear model functionality. SEMs are linkable modules of exchange content that can be combined to compose exchanges at run-time, that allow re-use of export and import functions for multiple domains, and that can be tested and certified as units. Thus they allow flexible exchanges, adapted to the needs of the day. See Figure One. Users can modify existing MVDs, by switching a few SEMs, or define a new one from scratch. They are composed grammatically, as shown in Figure Two. This provides users rich control how each object is represented for an exchange. Another objective of this approach is to make model views using IFC consistent and reusable by building them from tested and validated SEMs. Such a methodology will help reduce the development time for model views and IFC implementation, support the flexible definition and implementation of MVDs and provide better understanding of model views among users.
FIGURE ONE: SEMs as a layer of strong set of intermediate layer definitions on top of IFC, that allow composable implementation of translators.
FIGURE TWO: a partial composition structure for defining a model view using SEMs.