Structural BIM (Building Information Modelling)

 What is BIM? 

BIM is a collaborative tool used by any member of the architectural, engineering and construction (AEC) industry based upon a number of software solutions. BIM incorporates all the building components including their geometry, spatial relationships, properties and quantities, including all the services and equipment information for the full life-cycle management of the building and even its demolition. 

One of the main advantages of this way of working is that the different members of the AEC design team can utilize physical or reference models from other team members, without having any specialized industry knowledge. For example, the integration of services and structure schemes could first be co-ordinated by simply checking the objects from the two schemes to ensure clash avoidance. 

It is commonly acknowledged that the only solution for managing building information efficiently is with product modelling. This type of modelling was originally developed as a solution for the mechanical and plant design sectors. Since the early 1990s, structural steelwork detailing has made a remarkable shift from 2-D drawing to 3-D product modelling and a finite number of software solutions have played a pivotal role in facilitating this change. 

Structural BIM 

The use of a single 'total' BIM on large projects, containing all the architectural, structural and services object information, is still sometime away and may never be totally available. Structural BIM is the most important area for structural engineers and their immediate supply chain and is currently available. This multi-material (steel, concrete, timber, masonry etc.) subset can include the physical and analysis and design (AED) information, and can be used for all drawing and report production. 

Structural BIM is the part of the BIM process, where the majority of multimaterial structural information is created and refined to form the actual structure. Architects' models are not included in the scope of structural BIM, as these are not based on the same concept as this model. Architects work with space, mass, texture and shapes; they do not work with building objects in the same way as defined in the structural BIM. However, the connection between architects' models and structural BIM is a very obvious way to help in the future development of intelligent integration and these should always be available in the form of reference models, in the same way that the XREF function is used in a 2-D drawing. These reference models could also be 2-D information for collaboration with non-BIM applications. 

The model starts to evolve during the engineering stage, where conceptual decisions of the structural forms are made. It is sometimes thought that the design portion of AED is just the pure physical sizing of the structural elements. In practice it is more than that, as it should also include the engineering and the value engineering of the project, including all materials, their relationships and their reference to the architectural objects. 

The load-bearing structures are designed and integrated into the model and AED plays a significant role at this stage, though not in the classical sense of using separate independent tools. Structural BIM AED, is not a primary phase in the process. When changes occur, they are made directly in the structural BIM models with all AED results and all other output updated accordingly, as parametric objects can adapt and react to change. 

Open interfaces are fundamental for a structural BIM solution, not only from an interoperability point of view, however also from that of customization and localization. It is also easy to use open interfaces, which provide the opportunity to supplement the functionality of the structural BIM system with plugin software modules. 

Structural BIM is not an island of interoperability, so it needs to interface and synchronize with other applications and information. In the past the Steel Detailing Neutral File 9SDNF) and CIMsteel Integrated Standard Release 23 (cis/2), together with other industry or proprietary neutral file transfer formats. Globally Unique Identification Numbers (GUIN) are adopted sometimes to track element history between the analytical and physical models and to monitor change. 

The problem is that these formats have mainly been defined around the structural steelwork market requirements, as this was the lead sector. A multimaterial solution will always be required as even the structural steelwork contractors need to model their industries interfaces. These formats have provided a firm foundation for data interoperability; however, technically the future for data transfer has to be with the IFC developments, as this is the only way to support the round trip of true multimaterial objects. 

With the use of IFC and .NET technologies, BIM will become more transparent and complete within the next few years, as these two developments will greatly advance the interoperability of the BIM platform. The structural BIM is also not restricted just to members, as loads and load combinations can normally be handled within the modelling application. 

Finland Pavilion in Shanghai World Expo 2010 

Finland's pavilion for the Shanghai World Expo 2010 is called Kirnu, or 'Giant's kettle'. Tekla Structures BIM (Building Information Modelling) software is being used to model and manage its structural information in 3-D throughout the project. The use of Tekla Structures supports the pavilion being constructed as a laboratory for sustainable building. 

A World-Class Landmark : Mumbai Airport Terminal Building 

Mumbai's Chatrapati Shivaji International Airport (formerly Sahar International Airport) is the busiest airport in India, and caters to Cargo and Passenger flights. It has two terminals: the Domestic Terminal and the International Terminal. The domestic terminal includes two terminals: Terminal 1A and Terminal 1B. After the expansion and modification of Terminal 1B it was opened to the public on September 17th 2007. Tekla structures software was used to model this complex framework, thus ensuring highly effective detailing and optimized fabrication of this exceptional structure. 

World's Highest Railway Bridge crossing Chenab Bridge 

The world's highest Railway bridge crossing over Chenab river in India was also first designed in BIM  software. The Chenab bridge is extremely challenging logistically, as the terrain is rough and the roads are poor. The structure was modelled with Tekla Structures in its entirety, including base structures and also parts of the existing structure. During the different phases of construction, the bridge geometry was measured several times, and the rersults were compared with Tekla model.