Importance of Model Checking in BIM for a effective BIM Model

The constant development and growing implementation of the BIM methodology and technology, as well as of neutral and interoperable formats such as IFC (Industry Foundation Classes) and BCF (BIM Collaboration Format), led to an increasing interest in Model Checking tools and to the development of a new generation of software for Quality Assurance and Quality Control (QA/QC) based on parametric rules (rule-based); Model Checking is now an integrating part, and key element in Information Modelling and Management. Since it is not just mere tridimensional geometric modelling, BIM is based on the exchange of information related to programming, design, execution and management of an asset, through the different stages of a construction lifecycle and by involving all the interested parties.

The more the BIM method is being enforced, the clearer become the benefits and limits of this technology in exchanging information. On one side, the interoperability based on native models may increase production and efficiency, on the other, the use of a neutral format allows both open and side communication. It becomes clear how the most important aspect of this process is meeting the EIRs as well as data reliability, in order to avoid controversies.

The digitalization of the construction industry cannot leave aside the client’s capacity to define the conditions and contents of the interventions required in computational modelling. As a consequence, the validation of the parametric models must be a joint effort made by both the designers and the client in order to improve the quality of the project solutions, their consistency with the client’s needs and their support to cost analysis and the construction phase. This way the number of project modifications required during the work execution is reduced, a functional and quality building is guaranteed at the end, and, at the same time, process transparency has been increased.

Model Checking?

The model verification and the analysis of the results should be included in the standard routine and sufficient time should be allocated for it, including the time required to make any adjustment. During the Model Checking phase, the parameters implemented in the informative models, whether geometric or not, are analysed and validated by testing the Building Information Model through various validation domains. Generally speaking, the rule-set to check the model is organized in three phases of consequential verification:

1. BIM Validation,
2. checking modelling attributes and procedures,
3. Clash Detection, i.e. interference check,
4. and Code Checking,
5. verifying compliance with the correspondent regulation

BIM Validation Phase:

The proper implementation of the BIM methodology cannot be irrespective of consistency checks and quality of the data conveyed through a Building Information Model, provided that such model is structured to supply an effective tool to support the Information Management decision making process. Firstly, in order to ensure the communication between the Information Modelling BIM platform and the Model Checking BIM tool, the check rules and the model must contain the same semantics, that is to say, the parametric items included in the Information Model must necessarily be mapped and recognized by some Model Checking tool features; for this type of interoperability, the most commonly used are Name and Type. Before moving on to advanced analyses, a pre-check of the model informative content is required through a rule-set, in order to validate its accuracy: this is called BIM Validation phase.

Example of BIM Validation Executed with Solibiri Model Checker

Clash Detection:

Model Checking validates two types of data: geometric data and alphanumeric data. Clash Detection is a geometric and spatial consistence analysis, and is nowadays one of the most common applications of the Building Information Modelling. There are numerous benefits associated to such an analysis, which is performed in a short period of time and with minimal effort involved. Advanced Clash Detection occurs when the logical analysis skills of the Model Checking tool are able to distingush and classify the detected interferences. These will be classified according to several degrees of severity, previously defined in the BIM Execution Plan. Interferences between MEP and structural elements rather than between MEP and architectural elements, including the same design phase would require to be dealt with through a different approach.

The Clash Detection phase is developed through subsequent steps. First of all, the designer should be detecting any interference to his/her competence in the BIM Authoring platform. nowadays, the majority of parametric modelling software feature such applications or plug-ins in order to perform a preliminary check of the interferences or a partial BIM Validation of geometric aspects. BIM Viewer and BIM Coordination tools, such as Tekla BIMsight, Solibri Model Viewer, Autodesk Navisworks and Autodesk BIM 360 Glue can be used in the following multi-discipline coordination phase. Some of these are also available on mobile devices. In order to perform more advanced checks based in customizable rule-set, dedicated BIM tools are required, such as Solibri Model Checker, leader in the industry, which promotes an Open BIM access through an interoperable IFC format. 

Code Checking:

Code Checking is a declination of Model Checking by means of which the design may be validated by comparing the parameters included in the model with reference regulations and codes. The construction process is regulated by several rules at a local, national and international level, and the relevant information included in such documents can be translated into parametric rules through the support of a semantic reading and interpretation system. The same procedure applies to the client’s requirements or to good design and construction practices, since, once they have been translated into parametric language, they may be implemented as actual rules. Through a rule-based control system, the user is able to perform a check, whose results may be “pass”, “fail”, “warning”, and “unknown” (in case of incomplete or missing data).

Example from Solibiri - Accessibility Checking

Conclusion

The use of Building Information Modelling is developing more and more, and several countries are promoting a government based strategy in this direction. BIM is not just a mere technology twist, but rather a revolution of the process as a whole, which necessarily requires a different cultural approach. For this reason attention must be drawn to the type of tendering to be chosen, and promote collaborative tenders having their parties share both risks and earnings. In addition, the Validation process through the Model Checking should be a key practice in order to validate the content of the Building Information Model in a partially automated way. 

Sandya Devarajan

Lupiter Technologies

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