BIM for structural design

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More than simply a collection of tools for representing designs and engineering parameters, BIM is a practical technology shift that directly benefits engineersÝ productivity, collaboration, and accuracy says Phillip G. Bernstein, FAIA.

China, it seems, is one giant construction project, and like all giants, it has a large appetite ± in this case, for steel. Half a world away, ChinaÝs steel consumption has created indigestion for European architects and structural engineers, forcing them to struggle with the spiralling cost and availability of structural steel for their projects. With each change in the price of steel – sometimes weekly – project costs escalate, necessitating a constant process of redesign as teams strive to hit construction budget targets.

And with each such cycle, you can hear the cry of the structural engineers, asked once more to reduce the cost of the work: ýNot again!¯

Of course, China and steel is hardly the only challenge structural engineers face on projects large and small. And in most of those projects, the cost and associated tedium of these changes are skewed to the later stages of a project, as the architects and developers become better acquainted with the engineering issues.

ItÝs time to place some renewed vigour behind an idea structural engineers, architects and others have discussed for years: the extension of Building Information Modelling, or BIM, throughout the entire enterprise and industry. The core idea of BIM, applied to structural engineering, is to deliver information that is co-ordinated, internally consistent, and computable – that is, where the computer knows how to treat the aggregated data like a building. For many engineers, this is already accepted practice – and it has already begun delivering efficiencies and bottom-line benefits. Indeed BIM has reached acceptance among many architects as well, and in some cases the resultant collaborations have led to tremendous productivity gains.

" BIM affords an outstanding opportunity for structural engineers in particular to take a leadership role as the rest of the building industry begins to adapt and adopt model-based tools "

Unfortunately, BIM remains underused throughout the building process. Even if some professionals on a given project are using BIM and technology that supports it, the conventional design and construction process typically transfers information from one phase to the next via paper. Time has always been money, but in the modern building environment, this kind of disconnect among disciplines is too expensive and time consuming to continue.

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Properly integrated into the traditional processes between designers and engineers, BIM offers the chance to not only reduce the disruption of frequent or late changes, freeing up the engineersÝ time for more challenging work, but also to greatly improve client satisfaction.

BIM: practical and tactical vs transformational change

Often, technology changes in a traditional business such as structural engineering are portrayed as requiring dramatic transformation in the ways professionals work. Inherent in this view, though, is the notion that the transformation will be so profound that it will take years of work and a huge budget to implement.

It also has professionals wondering how their jobs will change – and if, in fact, the ýtransformation¯ will make it impossible for them to practice the profession for which they have trained in ways they understand.

BIM, however, can be viewed in a much different light. Its promise is not to create some incredible shift in the fundamentals of structural engineering. It wonÝt change the use of carefully constructed analytical models engineers have built over the years. Nor does it replace proven analysis applications like Robobat, CSC or Sofistik.

Instead, what it does provide is a common modelling front-end to interface with those applications and a common model to document the results. This provides both technical and tactical business advantages to structural engineering firms – improving communication with clients, speeding up the process of making changes that are out of the control of the engineer, and delivering final work products more efficiently. This can both improve profit margins and free up time to take on additional projects.

BIM can serve as an effective bridge between a structural designÝs analytical model and its physical representation and a link to the rest of the building process, offering breakthrough opportunities for efficient collaboration across design to construction – and a lot less paper. Purpose-built BIM software now exists for architects, structural and even building services engineers; technology that literally blends CAD with the data and 3D models resulting from performance analysis, in a high-fidelity, functional model.

By adopting technology that supports the use of BIM – and encouraging its adoption throughout the AEC industry – structural engineering firms can address four major areas of concern: creating greater efficiency through concurrent modelling; increasing the quality of work using parametric change management; improving design flexibility by better accommodating design alternatives and supporting more effective collaboration

Creating greater efficiency

For structural engineers whose work long has depended on analytical models that predict performance, the immediate promise of BIM and related tools and technology is greater efficiency.

Structural engineers must be particularly adept at reacting to late-stage changes that demand compromise because itÝs often ýtoo late¯ or too expensive to alter physical design. One of the major issues with last-minute changes to a project is the need to re-enter information for those changes. First, models must be updated to perform the variety of analyses demanded by changes in structure or materials. After those analyses are completed, the results must be communicated across the project team and require meticulous insertion of new data in all building documentation. Too often the resulting data isnÝt completely co-ordinated into the production documents, creating further difficulties in the field.

Typically those changes have been made using paper as the medium, or with multiple entries into discipline-specific software, both within the engineering firm and with designers and other partners. This kind of manual co-ordination and redundant data entry isnÝt engineering – itÝs tedious inefficiency, and a tremendous waste of the experienced professionals and highly-trained staff at an engineering firm.

BIM technology, by contrast, aggregates all the relevant data into a consolidated, dynamic model that is integrated with analytical models, architectural design and rendering software and that treats the data in that model holistically. Late-stage changes can be made with a minimum of data entry, drastically reducing the expense of those changes (which can wreck havoc on what little of a projectÝs budget remains toward a projectÝs end).

By eliminating the need to set aside large chunks of an engineerÝs time for the tedious redrafting and co-ordination of inevitable changes, that time can be used for a better purpose: engineering and problem-solving, which add far greater value to a project.

Improving quality

One of the natural by-products of the reduction in repetitive data entry made possible under the BIM structure is a reduction in the errors introduced by design changes. Errors are always a possibility whenever changes are made, because humans make mistakes. But errors are practically a given when the changes are complex, and are accompanied by the stress and rush associated with the late stages of a project.

When a client is demanding a completed set of documents to hit a delivery deadline, itÝs easy to imagine small computational mistakes cropping up – even in just one model, they will create errors, add to lost time, and translate to lost reputation as well. BIM can help avoid that problem through parametric change management capabilities.

In other words, a change made once to any parameter or element in the design is instantly reflected in every representation of that element in the design – including, with the right technology, bi-lateral links with existing specialised tools for analysis. Any other parameters that are linked to the change are also changed appropriately. The approach improves quality, because not only can engineers rely on the results, design team partners can count on the information provided to them to be the best possible quality.

The value is increased exponentially if those partners are also using technology that understands BIM data, because now everything is linked – and every change is reflected accurately all along the line. This is the vision behind an integrated, BIM-based project.

Better design flexibility

As long as the tedium of change management rules the day, what are the chances that engineers will examine all the structural design alternatives that present themselves with a late change in a project? Chances are the team will choose one or two alternatives their experience tells them are likely to work, methodically enter the data for the changes, run the numbers, repeat the process, choose the better of the two alternatives, and call it a day.

ItÝs always possible that another approach – a different strategy, or an alternate material, for example – would provide a better, more elegant or more efficient solution. With the time and budget freedom afforded by the use of BIM across the project, engineers are free to consider such alternatives – the kind of work for which they have trained. More flexibility also leads to more satisfied customers.

More effective collaboration

Even applying BIM in the structural engineering office alone offers great benefits. No matter how a projectÝs architects prefer to share design information, even on paper, BIM at the engineering firm makes it easier to analyse late changes and rapidly return the data to the architect for examination.

Within the last few years, however, technology has come to market to help architects make the transition to BIM themselves. The best of these technologies use parametric change management technology for the structural engineer. Linking these technologies together further eliminates errors while automating the communication of changes between the partners in the AEC process.

By now, itÝs clear that employing BIM from design to build creates a new kind of faster and more efficient collaboration. And that leads to better decisions all around – the kinds of decisions that involve big money. The IT Construction Best Practice Service notes that in the UK, the annual cost of rectifying construction defects caused by poor drawings and incorrect instructions has been put at ú1 billion.

The experience of structural engineering firm, Atkins Global is typical of firms that have begun examining tools for BIM and the potential impact on its work for clients in the government, commercial and industrial sectors. So far, the company has seen great benefits from using the one model for multiple third-party analysis, cutting this process down from two weeks to two days. The firm expects even greater gains, anticipating that overall, its teamsÝ documentation, drawing production and co-ordination, and integration of design changes will take place in a far timelier manner.

Conclusion

More than simply a collection of tools for representing designs and engineering parameters, BIM is a practical technology shift that directly benefits engineersÝ productivity, collaboration, and accuracy. While investment in training and transitioning staff is required to implement building information modelling, it is an investment that will quickly lead to tremendous benefits in both profitability and client satisfaction.

BIM also opens the potential to another transformation in the industry, one thatÝs key in this world of pressure on razor-thin margins and multinational teams and projects. These realities demand new business models that integrate design and construction, such as design/build, that combine some of the tasks and responsibilities that traditionally belong to separate architecture, engineering and construction entities. BIM offers the key to consolidating them within one organisation or project team.

Given that modelling abstract concepts forms the foundation of the discipline of structural engineering, BIM affords an outstanding opportunity for structural engineers in particular to take a leadership role as the rest of the building industry begins to adapt and adopt model-based tools to coordinate design intent, structural performance and execution and achieve quality design that yields high-performance buildings.

About the author: Phillip G. Bernstein, FAIA, is Lecturer in Professional Practice at the Yale University School of Architecture and vice president of the Building Solutions Division of Autodesk, where he sets the direction of technology solutions for the building industry. Bernstein was formerly an associate principal at Cesar Pelli & Associates Architects.

www.autodesk.co.uk

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