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AECbytes Product Review (October 31, 2006)

Bentley Building V8 XM Suite

Product Summary

Bentley Building V8 XM Suite is the new version of the integrated multi-disciplinary set of BIM solutions built on the MicroStation platform, and includes Bentley Architecture, Bentley Structural, Bentley Mechanical Systems, and Bentley Electrical Systems.

Pros: Inherits all the power and comprehensiveness of MicroStation's CAD platform in modeling, documentation, rendering, and animation; building information can be easily shared and integrated across the various disciplinary applications, facilitating collaborative multi-disciplinary design; its federated database approach lends itself much more easily and efficiently to distributed work processes, varied workflows, and large projects; several enhancements in the new version including task-based interfaces, an interface for organizing and accessing project files easily, improved editing, better graphics with real-time interactive shading, and many others.

Cons: Very complex, requiring a significant amount of time to master; requires the user to learn both MicroStation as well as the discipline-specific BIM application; requires a lot more work from the user in setting up the project, modeling it, extracting the necessary drawings, ensuring coordination between them, and managing all the component files and documents.


Earlier this year, I wrote about Bentley's V8 XM edition of its main platform product, MicroStation, which was unveiled at the BE conference, Bentley's annual user event. At that time, the V8 XM editions of Bentley's various discipline-specific products for different industries including AEC were still in beta. These products have now been released and include Bentley Architecture, Bentley Structural, Bentley Mechanical Systems, and Bentley Electrical Systems, all forming an integrated multi-disciplinary set of BIM solutions within the Bentley Building V8 XM Suite. This AECbytes review explores the main features of the Bentley Building Suite, including the enhancements in the V8 XM edition that are common to all its BIM applications. It will be followed by a combined exploration of Bentley Architecture and Bentley Structural in the next issue. Since these applications are being reviewed in AECbytes for the first time, the reviews will focus not only on the new features but also on their overall functionality as BIM applications for architectural and structural design.

Let us start by looking at some of the key aspects of Bentley's BIM solutions that differentiate them from other industry-leading solutions. These are applicable to all the solutions in Bentley's Building Suite.

Key Aspects of Bentley's BIM Solutions

There are three key aspects that can summarize Bentley's approach to BIM. First, Bentley sees BIM as a superset of CAD and wants to provide its users with a "ramp" as a transition path from CAD to BIM, without abandoning current capabilities. Second, Bentley has a "federated database" approach to BIM, where all the data related to the building is not centralized in a single building model contained in one file, but is instead distributed across multiple files in a coordinated fashion. And third, Bentley believes in "not starting over" with a new solution, and so all its individual discipline-specific BIM solutions are built on top of its existing MicroStation platform and TriForma extension.

The concept of a ramp from CAD to BIM is manifested in a key feature called "2D/3D Choice," which gives the user the choice of four different 2D/3D design modes: Drafting, where designers create 2D plans and other drawings only and not a 3D model; Plan to Model, where designers work in 2D, but a 3D model is dynamically generated behind the scenes and can be viewed at any point for visual feedback, but any changes made to the model do not affect the plan; Plan and Model, where there is a two-way relationship between plan and model, allowing designers to work either in the 2D plan or 3D model; and 3D Modeling, where designers work entirely in 3D mode, and any 2D drawings that are required have to be extracted from the 3D model. Users can choose the design mode by selecting the appropriate "seed" file (the term used for a template file) when creating a new project, and can subsequently switch to other design modes if needed. Since the option to work only in 2D is also available, all legacy 2D content can still be used. What makes it possible for Bentley's BIM solutions to offer these four different design modes is the separation of 3D model objects from their 2D plan counterparts accompanied by a sophisticated coordinated documentation technology for keeping them consistent. In contrast, in other BIM applications that have the centralized building model approach, there is no plan independent of the model—the plan is simply one view of the building object while the model is another.

The separation of 2D and 3D objects is ultimately a manifestation of Bentley's federated database approach to BIM, which also means that all the project data does not have to be stored in one file, but can be distributed across multiple files. This has several important implications for BIM, including project setup, organization, coordination, usability, project size, and so on, which are discussed in more detail in the next section.

Since all the Bentley BIM solutions are built on the common platform of MicroStation Triforma, building information can be easily shared and integrated across various disciplines, facilitating collaborative multi-disciplinary design. Thus, the structural and MEP components of a building, designed using Bentley Structural, Bentley Mechanical Systems, and Bentley Electrical Systems, can be seen and queried in Bentley Architecture, without requiring the original applications to be installed (see Figure 1). Similarly, the entities created in Bentley Architecture can be viewed and queried in the other applications and used as the basis for structural and HVAC design. A separate Interference Manager application is available to detect spatial interferences between the architectural, structural, and MEP models of a project. It is also possible to run all the Bentley Building applications that are installed in the same MicroStation session by using a Bentley Building Suite Icon instead of launching the individual applications. This is illustrated a little later on in Figure 3. Bentley's BIM applications are also integrated with Bentley Facilities, an application for space and asset management by building operators.

Figure 1. Viewing the structural model of a building, created using Bentley Structural, within Bentley Architecture. The design of this small hospital model is courtesy of Gresham, Smith, and Partners. (

How the Federated Database Approach to BIM Works

Bentley's federated database approach makes its BIM solutions very different from solutions like Revit and ArchiCAD that use the centralized building model approach, where much of the project organization and setup is already taken care of. For example, if you were modeling a 10-storey building in Revit, you could simply create the levels at the specified height in an elevation view; the application would then automatically create the placeholders for the floor plans at each level for you to model. Elevations, sections, and 3D views automatically show the entire model, and schedules can be created that collate information across the model. 2D and 3D views can be placed into drawing sheets, and are automatically updated if any change is made to the model. For example, if the height of any floor is changed, it automatically ripples through the entire model, adjusting the elevations of all the upper floors. While models can be divided into worksets for sharing between a project team or linked together to form a larger project like a campus, for the most part, users are working with a single project model where most of the basics are already taken care of and you can pretty much jump in and start modeling right away. (See the recent AECbytes reviews of Revit Building, Revit Structure, and ArchiCAD.)

In contrast, in Bentley's BIM solutions, the project information can be stored in a variety of ways to cater to many different workflows or setups that don't fit a preset standard. You can create the entire model in one DGN file (DGN is the native file format of the Bentley applications) and store all the extracted 2D drawings, views, sheets, and so on within the same file (similar to how you can create separate worksheets within the same Excel file), or you can choose to create separate DGN files for the models, drawings, sheets, images, other documents, and so on. Even for the modeling aspect, you can choose to create the entire building in one model, or break it down into multiple models in different ways: by floor, interior elements versus exterior facade, and so on. Thus, project organization becomes crucial when working with Bentley's BIM applications, and you have to spend time deciding on it and setting it up before getting started, as well as take care to follow the project structure as the project progresses. The project organization can be changed later if required, making the setup very flexible.

Prior to the V8 XM edition, the only way to organize a project was through the use of folders. Thus, you would create a folder for a project and create sub-folders in it for holding the models, drawings, and so on. This made it difficult to see the project structure and access the different files from within the application, a limitation that the new Project Explorer in the V8 XM edition has been designed to overcome (see Figure 2). You can now create one or more "link sets" in the Project Explorer, and within each link set, you can create links to different project data such as model files, drawing files, sheet files, and other documents, categorized in folders as required. This allows the user to navigate more easily through all the different components of a project, without leaving the application. Any file can be opened from the Project Explorer by right-clicking on it. Links can be created not just to a file but also to specific sections of a file, for example, a specific view in a DGN file, or a specific section of a Word document. Once a link set is created and saved in a specific location within the project folder, it is available in the Project Explorer window for all the files of that folder. As the project progresses and new files get created, options are available to automatically create the links for these files in the Project Explorer. While the Project Explorer may look similar to Revit's Project Browser or ArchiCAD's Project Map, the critical difference is that the Project Explorer in Bentley Building is an optional component rather than an integral aspect of the application. It provides a more convenient way to access the project files, whereas in Revit and ArchiCAD, it is the only way to access the different views of the model.

Figure 2. A link set in the Project Explorer allows easy access to the different components of a project.

Another aspect in which the federated approach is dramatically different from the single building model approach is that of coordination. In Bentley's BIM solutions, drawings are extractions from the model which are associated with it but are still independent. Thus, a change in the model does not automatically update the extracted drawing—because of the association, the change is detected and the drawing is recognized is being out-of-date. The user is then given the choice of updating it. While this provides more flexibility in letting the model and drawings be developed independently of each other, it also means that coordination is not guaranteed by the application but remains the onus of the user. The aspect of change management also ties in with the coordination issue. Since the entire building is not contained in a single model, changes such as floor heights cannot automatically ripple through all the floors; they have to be manually changed by the user.

While this federated, decentralized approach to BIM is undoubtedly more complex and less intuitive than the centralized building model approach, it is also what gives Bentley's BIM solutions their main edge over competing single model-based applications—the ability to adapt more easily to distributed work processes and handle projects of any complexity. The different files making up a project can be easily handled by several project members working simultaneously, and since the master model can reference an unlimited number of smaller models, which in turn can have any number of attached references of their own, Bentley's BIM solutions are able to model very large or complex projects just as easily as smaller ones.

Main Improvements in the V8 XM Edition

Since the BIM functionality of Bentley solutions was built on top of its existing CAD applications, MicroStation and Triforma, the interface of these applications in previous versions seemed more CAD-like than BIM-like, compared to the interfaces of from-the-ground-up BIM applications. This problem has been tackled in the XM edition with the introduction of some additional interface elements in addition to the Project Explorer described in the preceding section, all designed to make the applications easier to use. Topping this list is the Task Based interface, which allows the vast array of tools and commands in each application to be organized according to tasks (see Figure 3). For example, in Bentley Architecture, all the tools relevant to the modeling of floor plans such as those creating walls, doors, windows, stairs, and so on can be grouped in one category, while tools relevant to the modeling of the site can be grouped into another category. Similarly, in Bentley Structural, tools related to the creation of columns, beams, and braces can be grouped in a separate category from tools related to the creation of slabs and foundations. Each application comes with a number of different task interfaces to cater to different needs and levels of expertise; for example, Bentley Architecture has different task interfaces for Architecture, Advanced Architecture, New User, etc., while Bentley Structural has different task interfaces for Structural Physical and Structural Analytical. Users can also create their own task-based collections for various tasks at different design stages, which can be used individually or across a firm to standardize core processes and improve efficiency. It is also possible to have multiple task interfaces open at the same time and tabbed together to conserve screen real estate while still allowing for easy access, as shown in Figure 3.

Figure 3. The new task based interfaces for Bentley Architecture and Bentley Structural, docked on either side of the graphics window. They were made available in the same session by launching the Bentley Building Suite Icon.

While at first glance, the task-based interface in the Bentley Building applications may look identical to the tool palettes of other BIM applications like Revit and ArchiCAD which also have different tools organized in related categories, the difference is that the task-based interfaces in Bentley Building are fully customizable by the user. Also, the task-based interface makes a reference to a specific tool rather than physically placing in a designated tool palette, which means that the same tool can appear in multiple tasks. This leads to much greater flexibility in customizing the interface to improve the usability of the application.

Another enhancement in the XM edition that helps to improve usability is right-click context menus that are opened when an element is selected with the right mouse button pressed down, providing a number of tools that can be used to conduct operations on it. For example, the right-press menu for a wall element showing the available tools and modification options is shown in Figure 4. While this is a relatively common feature in many BIM and CAD applications, it will definitely be welcomed by Bentley Building users as it saves them from the inconvenience of having to go elsewhere in the interface to select tools from a task group, tool box, or menu to apply to an object.

Figure 4. The right-press menu for a wall element showing the available tools and modification options, making its editing easier.

All the Bentley Building applications also inherit the many additional new features and enhancements engineered in the V8 XM edition of MicroStation, which were summarized in my overview of the BE conference. These include better graphics with real-time interactive shading, allowing users to work directly in shaded views rather than working in line views and periodically shading them to better visualize the design; improved visualization capabilities for photo-realistic rendering and new animation tools; 3D modeling improvements such as creation of parametric 3D geometry, mesh modeling, and new handles for interactive editing; improved viewing and navigation in 3D; interface improvements such as dialog and element transparency, integration with PANTONE colors, and display priority; keyboard mapping that allows each user to configure their entire keyboard as desired; support for 3D PDF, allowing an entire project including 3D models, 2D drawings, specifications, and other documents to be packaged in a single PDF document; and integration with Google Earth, allowing a building modeled with the Bentley Building applications to be exported to Google Earth with the correct geo-referencing information, so that it can be viewed on the actual site. Google SketchUp and the Google 3D warehouse are also fully supported. In addition, anything drawn, modeled or imported into MicroStation can have BIM information added to it, allowing virtually any kind of geometry to be BIM aware.

Analysis and Conclusions

The features that have been described so far in this review barely scratch the surface of the full range of capabilities of the Bentley Building applications. Since they are built on top of MicroStation, a very powerful and comprehensive CAD application, the Bentley Building applications incorporate all of its many capabilities: a full range of surface and solid modeling tools; powerful visualization and animation capabilities including full-blown radiosity that can create highly photorealistic renderings and animations; a vast array of dimensioning and annotation tools for creating drawings and details; a Design History capability, which can track changes to models and restore a model, if desired, to a prior state; the ability to work directly with DWG/DXF files; support for several database formats allowing data to be imported as well as exported; full import and export support of IFC 2.0 through IFC2x3; and the ability for users and third party vendors to extend and customize the applications using APIs. The Building Suite also includes additional utilities such as the DataGroup System, which is used to manage application and user defined building objects and instance data for modeling, drawings, and scheduling, and includes the ability to add custom information and apply user-definable attributes to virtually any object in a 2D/3D file; and the Parametric Cell Studio, a standalone application for the creation of parametric objects such as doors, windows, casework, curtain walls, stairs, trusses, etc.

The flip side to being built on top of MicroStation is that users will essentially have to master not one application but two, if they are to take full advantage of it. Thus, architecture users will have to master MicroStation as well as Bentley Architecture, while structural engineering users will have to master MicroStation in addition to Bentley Structural. This is also evident in the installation of the applications—MicroStation has to be installed first before any of the Bentley Building applications can be installed. Even the documentation is not self-contained—for help with any of the base platform functionality, you will have to refer to the documentation for MicroStation. For users for whom the complexity of CAD and BIM applications is already an issue, it is vastly compounded with the Bentley Building applications. Mastering them along with MicroStation will take a serious amount of time and commitment. In that context, good support becomes critical, and most users opt for Bentley's "SELECT" update and support program, which provides full 24/7 access to phone support at no additional charge as well as access to a large collection of online on-demand learning opportunities.

While the interface improvements in the V8 XM edition are definitely a step in the right direction and will improve usability, I found that given the overall complexity of the applications, their impact on the overall ease of use was not that significant. In other words, the "guts" of the applications remain unchanged. As described earlier, the federated database approach in the Bentley Building applications, in contrast to the centralized building model approach, requires a lot more work from the user in setting up the project, modeling it, extracting the necessary drawings, ensuring coordination between them, and managing all the component files and documents. But on the plus side, it lends itself much more easily and efficiently to distributed work processes, varied workflows, and the sharing of information among design teams in multiple offices, aspects that become particularly critical for large projects.

Bentley's BIM solutions can be easily summed by just a few words: very powerful but also very complex. It is hardly surprising, therefore, to find that they are most commonly used by large firms, for multi-disciplinary design, and for very large projects such as airports, stadiums, campuses, and so on. I don't expect to see that changing anytime soon, unless Bentley moves to a radically different approach to BIM.

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at

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