RST - Chapter 1: Building Information Modeling

Building information modeling (BIM) is an integrated workflow built on coordinated, reliable information about a project from design through construction and into operations. The Revit platform is purpose-built software for building information modeling.
Building information modeling (BIM) makes sustainable design practices easier by enabling architects and engineers to more accurately visualize, simulate, and analyze building performance earlier in the design process.

Chapter Objective

In this chapter, you will learn about building information modeling methodology.

Lesson: Building Information Modeling for 

Structural Engineering

This lesson describes the building information modeling (BIM) process for structural engineering. Applying building information modeling results in better drawings, shorter timelines, and improved productivity. It offers an opportunity for building industry professionals to design, construct, and operate buildings of higher quality at a lower cost and at reduced environmental impact.

Objectives

After completing this lesson, you will be able to:

• Describe building information modeling.

• Describe bidirectional associativity.

About Building Information Modeling

Building information modeling is a building design and documentation methodology based on coordinated, reliable, high quality information. It enables design and construction teams to create and manage information about a building project consistently and reliably across the scope of the project. The information is stored in a single building model. This ensures that the information is coordinated, consistent, and complete.
The building industry has traditionally illustrated building projects with manually created drawings. Information was added to these illustrations by using notes and specifications. With the advent of CAD technology, this process was automated. However, the output of manual drafting, graphics CAD systems, and object-oriented CAD systems remained the same: a graphic abstraction of an intended building design.
The development of the building information modeling methodology represents a new way of thinking and working. The ability to model with objects minimizes tedious drafting by having one 3D object handle multiple 2D representations when placed in a project. More important is what you can do with the model. You use the coordinated data inherent in the model to visualize, simulate, and analyze your designs and make better informed design decisions.
Building information modeling supports large team workflows to improve project understanding and enable more predictable outcomes. The visibility that BIM provides to all members of the project team contributes to its success through better coordination, improved accuracy and the ability to make more informed decisions earlier in the process.

Definition of Building Information Modeling

BIM is an integrated process that allows professionals to explore a project’s key physical and functional characteristics digitally before it is built.
Coordinated, consistent information is used to:

• Design innovative projects from the very earliest stages

• Visualize, simulate, and analyze real-world appearance, performance, and cost

• Document accurately

• Deliver projects faster, more economically, with reduced environmental impact

By adopting BIM, architects, engineers, contractors, and owners can easily create coordinated, digital design information and documentation.

Autodesk Revit Structure and Building Information Modeling

Revit Structure is purpose-built software for building information modeling. Traditional drafting and CAD software represent the geometry of a design by using stylized symbols from designated illustrations. Some examples of these illustrations may be a series of plans, elevations, and sections. These illustrations are essentially independent of one another.
Building information modeling software represents the design as a series of intelligent objects and elements such as walls, beams, schedules, and plan views. These objects and elements have parametric attributes. The information about these objects and elements is stored in a single building model. You can extract any number of different views of the data from the model.

Revit Structure is a building design and documentation system that supports the design, documentation, and even construction efforts required for a building project. Because of its parametric change technology, any change you make is automatically coordinated everywhere in your project, including model views, drawing sheets, schedules, sections, and plans.

Building Information Tailored to the User

When using a building information modeling process, the building information is stored in a single building model instead of in a format predicated on a presentation format, such as a drawing file or a spreadsheet. The building information model presents intelligent data for editing and review in views and formats that are appropriate for and familiar to the user. Some examples of these formats are a structural detail or a framing plan.
For example, information such as structural beams are represented differently in a framing plan than they are in a structural detail. While the beam is represented by a symbolic line in plan, and a realistic representation in detail, both are different representations of the same structural element. Managing Change with Building Information Modeling Building information modeling solutions manage iterative changes in a building model throughout the design, construction, and operation phases. A change to any part of the building model is replicated in all other associated parts.
Maintaining a single, internally consistent representation of the building can improve drawing coordination and reduce the number of errors in the documents. As a result, building documents can be of higher quality, and the costs of changes and coordination reduced. Building information modeling tools can enable the design, construction, and occupancy of the building to proceed with less friction and fewer difficulties than conventional tools.

BIM for Structural Engineering

BIM for structural engineers follows the same methodology for the entire structural engineering process, focusing on a digital design model that can be used for coordination with architects, and mechanical, electrical, plumbing, and civil engineers. BIM is integrated with analysis, design, and construction documentation. The design model can also be extended from design through fabrication and construction. Autodesk has a complete portfolio of structural engineering software that supports this end to end workflow.

At the center of the BIM workflow is Autodesk Revit Structure, integrating a multi-material physical and analytical model. This single model can be created on its own, or by leveraging 2D or 3D architectural information.
The Revit Structure model can be used throughout the interactive design process to collaborate with all parties involved. The result is a coordinated and consistent design model that reflects the most upto-date design.
The analytical model is used to integrate Revit Structure and widely-used industry standard structural analysis and design applications, such as Autodesk Robot Structural Analysis Professional. The analytical model contains information such as loads, load combinations, member sizes, and release conditions for use in leading third-party analysis applications. The creation of the analytical model uses engineering rules to produce a consistent analytical representation of the physical structure.Engineers can override initial analytical settings and edit the analytical model before linking to structural analysis packages.
Autodesk Robot Structural Analysis Professional software is a collaborative, versatile, and fast structural analysis and design application that incorporates BIM, allowing engineers to readily analyze a wide variety of structures.
Revit Structure is also used to create the construction documents required for the project. Its bidirectional associativity ensures that changes made to the model are automatically updated on every sheet of the construction documents. Revit Structure can also be used in conjunction with AutoCAD to leverage the power and productivity of the widely-used drafting platform, providing a robust and powerful solution for construction documents.
Finally, the same model can be used downstream for fabrication detailing and shop drawings of steel and concrete reinforcement using leading third-party detailing applications as well as AutoCAD Structural Detailing. AutoCAD Structural Detailing software is a powerful solution for faster and efficient detailing and creation of fabrication shop drawings for reinforced concrete and steel structures.

About Bidirectional Associativity

A key feature of Revit Structure is bidirectional associativity, which ensures that changes to any elements of the design model are immediately reflected in all views where those elements appear.

Definition of Bidirectional Associativity

Bidirectional associativity is the ability of the building information model to coordinate changes made in any view and propagate these changes out to all other views. Bidirectional associativity is applied automatically to every component, view, and annotation. For example, a change in the size and location of a column is reflected in all plans, details, and schedules; all of which are associated with the column and influenced by the change in the column properties. The beams framing into the column are also affected by the changes and are automatically adjusted. Revit helps ensure that plans, schedules, and building sections and elevations are immediately available, up-to-date, and accurate.

Parametric Relationships

The term parametric refers to the relationships among the elements of a building design model. These relationships enable the software to coordinate and manage the changes made to the building model. The relationships are created either automatically by the software or by you. In mathematics and mechanical CAD, the numbers or characteristics that define these relationships are called parameters; therefore, the operation of the software is called parametric. It is these parametric relationships that deliver fundamental coordination and productivity benefits provided by the building information modeling methodology.

Updating the Design Model

A fundamental characteristic of Revit Structure software is the ability to coordinate changes and maintain consistency. You do not have to intervene to update drawings or links. When you change something, the bidirectional associativity feature of the software determines the elements that are affected by the change and propagates that change to any affected elements.

Examples of Bidirectional Associativity

• Flip a section line and all views update.

• Draw a wall in plan and it appears in all other views including material takeoffs.

• Change a beam or column type in a schedule and the change propagates throughout the graphical and non-graphical views.

Examples of Parametric Relationships

• Beams attached to supporting columns located on column grids. When a grid moves, the column moves with it and the beams lengths adjust accordingly.

• A structural truss modeled using constraints that define the number of bays and lengths of diagonals. When the span of the truss changes, vertical members are added where necessary and the diagonal web members adjust accordingly.