Building Information Modeling (BIM) Principles - study material

1. Building Information Modeling (BIM) Principles

In the construction industry, BIM causes a fundamental change, which by efficient handling of information contributes to a higher quality project, saving construction time, supports a more precise construction process, easier control and, above all, contributes to the reduction of operating costs. However, this is not an entirely new concept.

The goal of BIM is not to create a model itself, but to gain complete, reliable, accessible and easily exchangeable information to anyone who might need it throughout the whole life cycle of the building. These challenging tasks can be handled with the help of innovative approaches, systems and, finally, with the help of computer technology and high-quality software equipment. We need to transform the construction industry into the 21st century and increase the digitalization and automation rate.

One of the essential prerequisites for BIM is to set a cooperation between all stakeholders at different stages of the life cycle. Within the workflow, it is necessary to allow users to enter, change, updating or correct any information in the model that is relevant to their roles in project. Virtual model is composed of 3D parametric objects that allow to bear an information by using specified data format. By assembling them together, we make so-called virtual construction resulting in improved quality of a project. While using traditional CAD (Computer Aided Design) it is quite often that just a limited part of a building is designed and most of architects are selecting simplest sections to make their job easier. They don´t care what is 200mm behind the cut section and this might lead to delay in construction and makes the coordination of a project impossible. On the other hand, by using BIM, architect is obliged to design all details in a building so this certainly results in coordinated project in high quality which is moreover much easier to check.

Not many people are aware that BIM is not just about buildings and civil engineering, but of course highly suitable also for infrastructure - railways, highways, bridges, etc. Some people in practice perceive BIM just as a visualization or a 3D model.

The task of BIM is not to replace experts with software, but to provide them with a quality tool to simplify manual and repetitive work. However, this approach completely changes the way of looking at the hitherto used procedures of companies in the construction industry and conceptually contributes to more efficient and systematic work with the exclusion of a number of mistakes, or irregularities even before the actual construction phase. However, the software cannot be used as a substitute for relevant professional education and experience.

An information model is defined as a set of structured and unstructured information containers (STN EN ISO 19650-1). The very term information container (permanent group of information) is relatively new for the field of construction. In principle, this is information that can be repeatedly retrieved from a file, system or other storage, e.g. drawing, budget, schedule, model geometry, or image. BIM, or Building Information Modeling is defined by this standard as the use of a shared digital representation of a built asset to facilitate the design, construction and operation processes so that they form a reliable basis for decisions.

Building information modeling is defined in (STN EN ISO 29481-1) as the use of a shared digital representation of a built object (including buildings, bridges, roads, process equipment, etc.) to simplify design, construction and operational processes, to create a reliable basis for decision-making.

The BIM model is essentially a 3D parametric data model that contains all information about the building, which is defined as an asset from the point of view of the standard (STN EN ISO 19650-1). Information has high potential if it is entered into the model from the initial phase of the conceptual intention, through project documentation and subsequent construction to facility management (FM). Information from the data model, which is a virtual representation of the real object and contains all structures, elements, spaces, their properties and parameters, is easily available and it is clear that in the foreseeable future they will play a decisive role in the management and operation of buildings. We often come across a situation where authors often inappropriately use the term digital twin, which from their point of view is synonymous with the information model of the building in the operational phase - in the sense of the standard we are talking about the asset information model (AIM) . The Operational Phase is defined by STN EN ISO 19650-1 as the part of the life cycle during which the asset is used, operated and maintained. Asset is a relatively unused term in the field of construction, under which we can imagine any building or structure, as the standard defines it relatively generally as an item, thing or entity that has potential or actual value for the organization.

Building information modeling is the process of developing and using a virtual data model that not only documents the architectural design, but also simulates the construction and operation of a new or renovated building. The resulting virtual model is a data-rich, object-oriented, intelligent and parametric digital representation of the object, from which information corresponding to various user needs can be obtained and analyzed to create feedback and improve the design of the object. It is therefore a suitable tool for demonstrating the complete life cycle of a building. However, the composition of the work team is changing, as well as the time in which individual participants enter the process.

In the past, the English word "building" was interpreted as a building in the definition. Later, however, this definition was modified and today we translate the word "building" as construction. From the point of view of the life cycle and standards (STN EN ISO 19650-1), however, we can perceive the building as an asset, something that has value. However, still few people in practice realize that BIM is not only about civil engineering, but of course also applies to engineering constructions - railways, highways, bridges, or water management structures.

A model that is correctly filled with information from the beginning is a basic prerequisite for further use in the following phases of the project. Accessing such data is easy and its reuse is more efficient, eliminating a lot of unproductive time. The scope of work associated with the delivery of work in BIM is diametrically different from traditional projects and requires a greater emphasis on machine-readable data.

BIM must use parametric modeling. Parameters are static or dynamic properties that define geometric or non-graphical characteristics of 3D objects in the model. If we change a dynamic value that is tied to the element's geometry, this results in an aggregated set - a set of induced changes. In general, parametric tools are best for creating very elaborate and complex products, many product lines, or when working in an industry that is heavily regulated by standards. The opposite method is explicit forms of modeling.

1.1. BIM dimensions

In the context of BIM, the concept of dimensionality often appears in professional literature. However, the problem is that different authors define these dimensions, or aspects of BIM differently. However, this is not about expanding the dimensions from a mathematical point of view. From a BIM and mathematical point of view, the dimensions correspond to the third dimension - that is, in 2D and 3D. However, if we add another dimension to 3D, from a mathematical point of view, a 4-dimensional space would be created, and then a 5-dimensional one. In the case of construction and systems, or programs used for projecting, planning and control of construction, or the construction process, the letter "D" does not mean a multidimensional space, but individual information components that we assign to the model. Designations like 6D, 7D, etc. they are not uniform and for this reason misunderstandings occur. We therefore recommend not using these terms.

4D BIM

In the case of 4D BIM modeling, we place the 3D elements of the model on the timeline, which creates a simulation of the construction process, with the help of which we can move to any day of construction. In addition to an effective presentation, it allows us to solve situations, technological conflicts (time collisions) and possibly also inconsistencies in construction solutions that may result from the project.

We can create a 4D simulation in two ways. The first way is to manually connect 3D objects (wall, column, window,...) to items within the timeline. However, this method is very laborious and difficult to update in case of changes. The second way, based mainly on the essence of parametric modeling, is automated creation by defining whether individual technological and spatial properties are taken over by the building object and we can also determine their sequence of construction. The time schedule compiled in this way is based directly on the model and therefore reduces the possibility of errors, such as the omission of some components, building constructions, or incorrect technological sequence.

Closely connected to the 4D model is the measurement report, which is an essential part of the documents needed to create a time plan. If we use CAD systems, its creation is very laborious and in certain cases inaccurate. Individual structures must be identified and manually recalculated. In this process, errors occur due to incorrect calculation or omission of construction. However, if we use parametric modeling, the measurement report is an output that can be generated with a certain degree of automation based on the materials, objects, and elements used.

5D BIM

Adding another aspect to the information model creates a 5D model that extends 4D with a cost component. With the help of this model, we can monitor the exact need for funds in each monitored unit of the project's life cycle. Simply put, 5D makes it possible to better plan the financial side of the entire project over time.

After 5D, the authors agree on defining the individual components of the model. However, different authors differ slightly in other aspects, such as 6D and 7D. Some refer to 6D as life cycle management (Hitchcock, 2011; McPartland), or as facility management (Fredrickson, 2011; Regarding 7D, the authors are also inconsistent, some authors state that it is an aspect of facility management (Akillian, 2012; AIC 2013) , others define it as occupational health and safety (Hitchcock, 2011; Fredrickson, 2011).

1.2. Common Data Environment - CDE

BIM is characterized by interdisciplinary cooperation, and for this purpose the common data environment (CDE) can be used, which in terms of the standard is defined as an agreed source of information for each given project or asset, for the collection, management and dissemination of individual information containers through a controlled process. However, it is not just a virtual shared folder, but enables communication about any part of the model, or buildings. The information managed in the CDE should be comprehensible to all parties.

The common data environment is a central source of project-specific information and is used to collect, manage and disseminate all relevant approved project documents for multidisciplinary teams in a managed process. Thus, we can imagine CDE as an imagined online place that provides a framework for the digital collection, sharing and exchange of information about a construction project.

From the point of view of STN EN ISO 19650-1, CDE has four defined areas:

• Work in Progress - contains unapproved information intended only for team members.
• Shared (Shared) - information that has been checked, commented on, verified and subsequently agreed to be shared with other suppliers, or organizations that can use them as a basis for their further work. After completion of all parts of the project, complete data are provided to the customer for approval.
• Published (Published) - information that was agreed by the customer for use for the purpose of securing the construction, but also in other phases of the life cycle.
• Archived (Archive) - saved important information and records about the project.

Figure 1 Status of documents defined in STN EN ISO 19650-1

Working in such an environment clearly defines the process for handing over the model and its components, or documents. Individual models made by different members of the project team have clear authorship and remain virtually separate.

This means that the creator's responsibility does not change after a part of the model is incorporated into the federated (merged) model. It is important to mention that ownership of information and all content created by the designer when using CDE is clearly and unambiguously identified. Some systems are even certified according to the international ISO standard, and in the event of a dispute, these records can also be used in court to prove authorship, or the date and form of delivery.

In general, the customer is granted a license to use the information contained in the individual models for a pre-agreed purpose. Based on this license, the customer allows project team members to use models prepared by other project team members.