A new challenge in design: BIM (Part 1: what is BIM and why we use it)

It is well known that, as a design process starts and evolves, it gets more and more difficult to conciliate all the requests coming from the involved professionals. During the traditional process of design and construction of a building, most of the expenses come in the construction documentation phase and are due to changes and planning mistakes: the more advanced the design phase, the more expensive the modification.

MacLeamy diagram: Traditional design process concentrates most of efforts in advanced phases, with high costs.

Pre-built structures are more affected by this problem than traditional buildings, because they require clever engineering of the product, as it normally happens in mechanical industry. This means that, during the construction of a timber building, bumping into changes in the design can be highly unpleasant, because the whole product development process would be shaken; in a nutshell, there would be higher expenses and delays in construction!

Timber constructions, as all other pre-built realities, need to embrace a new design philosophy, that could solve most of the issues at early stages, in order not to slow down the building operations. This new method employs 3D modelling softwares, that use BIM technology.

MacLeamy diagram: BIM process gathers design efforts in early stages of the engineering process, where potential changes do not result in huge rises in costs.

Ergodomus Timber Engineering is up to date with the new philosophy regarding the engineering process, and uses BIM to develop its projects. Since this technology is continuously evolving, the staff of the company has started a research aimed to discover the potentiality of BIM when applied to timber structures. The research was done in collaboration with interns from University of Bologna (second level postgraduate degree in Timber Constructions).

What do you mean by BIM?

According to its most known definition, Building Information Modelling is the use of a shared digital model representing an object (such as a building, a bridge, a plant, and so on), in order to simplify design and construction processes. The NIBS (National Institutes of Building Science) describes BIM as a “digital representation of physical and functional characteristics of a facility”. That is because models generated with a BIM technology aren’t mere 3D representations of a building, but they also include information data regarding a number of components (geometry, material properties, structure, MEP, energetic performance, building site, building management, and so on). Moreover, with BIM it is possible to capture specific features and automatically generate documents such as bills of materials and tables of construction phases. CAD softwares using this technology are based on a drawing which is no more a set of lines and dots, but a multimedial object containing lots of information (for example, a wall-element may contain data regarding: geometry, stratigraphy, materials, transmittance, costs, and so on).

What could be the potentialities of BIM in the field of timber constructions?

Wooden structures require a very accurate design from the beginning of the process. The effectiveness of BIM can thus be summarized with two key-words:

1. Process engineering. The model contains all the data needed to automatize the construction of the building.
2. The model can interact with those made from other professionals involved in the design process.

There are various specific CAD softwares for timber structures. Generally, we are dealing with CAD/CAM softwares, that merge (Computer-Aided) Design and Manufacturing.

Ergodomus uses the software HSBcad, which is a CAD/CAM software for timber buildings, based on the Autodesk technology (Autocad Architecture and Revit).

This software can generate 3D models of every possible typology of timber buildings (from Timber Frame to CLT buildings), integrating them with data about the type of object (beam, panel, column, slab, and so on), its geometry, material, manufacturing (drilling, saw-cuts, milling). It is possible to convert the file into two formats: CNC-files (interface with Computer Numerical Control machines) and IFC (exchange format between BIM platforms). It is also possible to generate details, 2D drawings of the model and bills of materials.

Structural model of Pavilion of Innovation – University of Parma, generated with HSBcad and Autocad Architecture

The CNC output format can be imported from a CNC machine and used to automatically produce beams and panels.

What is the use of IFC?

The answer lies in the next article, in which we are going to show you all the pros and cons of BIM.

Written in collaboration with Francesca Bifulco, engineer and post-graduate degree in Timber Engineering, University of Bologna.