The co-ordination of multi-disciplinary models in a single environment is one of the foundations of Building Information Modelling. Greg Corke looks at a free tool from structural BIM specialist Tekla that enables engineers, architects or anyone involved in construction to do just that.
With Building Information Modelling (BIM) one of the primary benefits is the ability to co-ordinate architectural, structural and MEP (Mechanical, Electrical, Plumbing) models. Clashes can be ironed out and construction challenges resolved before anyone gets near a site – potentially saving lots of time and money.
However, of those that have fully adopted BIM working practices – and in the UK the percentages are still quite low – many are not taking full advantage. Co- ordination often happens late on in the design process, just before construction starts, and at this stage the potential to improve design or cut costs is reduced.
Finnish company Tekla, best known for its structural BIM software Tekla Structures, is trying to change this. Its new software tool, Tekla BIMsight, can import models from virtually any BIM application via the Industry Foundation Classes (IFC) format, an open data model designed to describe building and construction industry data. Users can carry out spatial co-ordination, perform visual checks for design and constructability issues, automate clash detection and mark up the multi-disciplinary model with notes and redlines.
While this is nothing particularly new, the key difference between Tekla BIMsight and applications like Autodesk Navisworks, Solibri Model Checker and Bentley Navigator, is that Tekla’s software is free. Architects, engineers, contractors and subcontractors can all get their hands on the software gratis. The only stipulation is that they have to register their details after ten uses.
The rationale behind this move is primarily to drive the use of digital information models and promote demand for them. Tekla also wants to raise its profile as, while the company is well known in the structural sector, its software is not really on the radar of architects and MEP engineers.
The company also wants to promote the concept of Integrated Project Delivery (IPD), whereby everyone is signed up to the design process nice and early. This means all subcontractors – including steel and pre-cast, cast in situ, whoever they may be – can collaborate on the design, make suggestions for improvements, or increase the use of off-site construction methods, for example, to reduce the cost of the overall project.
With Tekla BIMsight the company is promoting collaboration through the use of reference models. Here, the model is not coordinated in a single live environment; instead each party – architect, M&E and structural engineer – periodically publishes models in IFC format to a central location for group discussion, either together in a room or over the internet. Design co-ordination is managed by the contractor and all parties can collaborate in Tekla BIMsight to identify issues. The key idea is that everything happens early on in the design process.
While there is currently a big emphasis on using Tekla BIMsight at the early stages of design, there is also a big role for it to play during construction. With Trimble’s impending takeover of Tekla we expect to see closer links form between the construction model and Trimble’s on site positioning technology.
Tekla BIMsight was originally launched in February 2011, but the first versions were effectively beta software and the latest 1.2 release is considered to be the first ‘complete’ version. The interface is clean and clear and there are plenty of instructional video tutorials to help non-technical users get up to speed.
Reference files are typically brought into Tekla BIMsight in IFC format, though DWG and DGN are also supported. Depending on the workflow adopted by the users of each authoring software, IFC models are typically broken down into areas, such as by floor or building. Once inside, the software reference files can be organised into groups – e.g. architectural, structural, and MEP – making it easy to isolate individual parts of a project when required.
Users have total control over what’s displayed on screen and at any time models or model groups can be toggled on/off. Visibility control can even go down to an object level, and users can zoom in on individual beams, walls, or columns by picking objects off a list.
Objects can also be selected off screen, either individually or by area. Users can then drill down to get more info, ranging from spatial co-ordinates all the way down to weight, steel grade or finish.
Viewing 3D models
Models can be viewed in 3D, orthogonal or perspective and users can navigate their way around using all the usual rotate, pan and zoom controls.
Models can be shaded with solids, transparency or X-ray or sectioned using clipping planes to help expose details inside a building.
Any view can be saved for reference later with a handy icon stored at the bottom of the screen for quick reference. In addition to the orientation and zoom level, saved views remember which objects are visible, as well as any clipping planes used.
While Tekla BIMsight models are quite lightweight in terms of size (MB), they can still put a fairly hefty load on the graphics card. Loading up Tekla BIMsight’s standard datasets on a two-year old CAD workstation, we noticed that frame rates slowed down considerably when architectural, structural and MEP models were all made visible at the same time.
Tekla’s minimum recommended specification is a multi-core processor with 2GB RAM and an OpenGL graphics card. We found it will work on standard desktop PCs, but to get a better experience when working with large models we’d recommend a workstation or workstation-class laptop with a powerful graphics card and a high GHz processor.
As part of Tekla’s overall strategy to promote the use of Tekla BIMsight early on in the design process, the software is said to offer ‘clash prevention’, rather than ‘clash detection’. Here users define rules to govern which models or model groups are checked against each other and what tolerances they are measured against. For example, the contractor or engineer may not be bothered if a pipe overlaps a structure by 10mm as these low level clashes can easily be sorted out on site.
Significant conflicts are presented in a list and the user can step through each clash in turn. Double clicking on a clash automatically zooms to its location in the model, and the user can then assign notes or change its status (pending, resolved, etc). Changes to status can also be made on several objects at the same time, simply by selecting them in the model window.
Once problem areas have been identified, changes will need to be made in the originating BIM software. This can be done by simply using the Tekla BIMsight model as a visual reference or feeding back the spatial co-ordinates of the clashing element to the architect or engineer who can then adjust the design accordingly.
For real-time collaboration, sessions can be hosted using established technologies such as gotomeeting. TBP files (Tekla BIMsight’s native format) can also be saved and distributed using tools like Dropbox or dedicated project collaboration portals like 4Projects. The compact file structure used by Tekla BIMsight means even large building models are only in the order of 100s of MB.
To further aid collaboration Tekla BIMsight version 1.2 now includes new markup tools. Notes and redlines can be added to specific objects, the current view saved and a thumbnail view assigned for easy reference. Each note is attributed to the user that defined them.
In a similar way to conflicts, notes can stepped through in turn. They can be sorted by type in the right hand panel or browsed in the model window as each is assigned a visual tag. Once a note is selected it will automatically take the user to the saved view.
A neat feature of Tekla BIMsight 1.2 is that external documents can now be added to any object within the model. For example, a PDF of a product specification or a photograph showing an on-site issue.
Tekla BIMsight is an impressive tool, particularly when you consider that it’s free. It’s easy-to-use, even for non-technical users, and while it lacks some of the powerful 4D project scheduling features found in Autodesk Navisworks and Bentley Navigator, what it does in terms of model co-coordination, collaboration and clash detection it does very well. That’s not to say 4D project scheduling won’t appear in the product in future releases. Tekla has the technology – it is already a key part of Tekla Structures Construction management software – but there’s naturally a cost for this functionality.
Tekla has a bold vision for Tekla BIMsight. It wants it to be the ‘Adobe Reader of the AEC market’. Of course, there’s still has a long way to go, not only because it needs to build awareness across all sectors of construction, but widespread sharing of BIM models still requires a significant cultural change throughout industry.
There are also other challenges. While IFC is certainly the preferred format for BIM model data interoperability, the quality of exported data can vary from application to application. Some BIM software developers’ IFC files have even been know not to work between their own applications and users may also find certain building elements don’t have an IFC description. Furthermore, while the format is popular in some geographies including Scandinavia, awareness of the IFC format in other regions still needs to grow.
Industry challenges aside, for anyone that currently creates BIM models, whether that’s architectural, structural or MEP, Tekla BIMsight is well worth a test-drive. There’s certainly huge potential here for the AEC industry.