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Clash Detection

Mauro 2020-09-18 09:07:57

This is a specific issue related to model checking: dealing with Clash Detection.

Model checking in the BIM process
In the development of a digital workflow for the creation of a federated BIM model (a model resulting from the union of several models relating to different design disciplines, e.g. architectural and structural models) that allows a good integration between the models created by different project teams, among the fundamental activities, we find the verification and management of interferences and inconsistencies.

These activities are defined by the various general concepts and international ISO standards directly connected to the nature and origin of information and are as follows:
- geometric interferences analysis: a check of possible geometric interferences between objects, models and designs with respect to others, the consideration of the term Clash Detection;
- inconsistencies analysis: a check of possible information inconsistencies between objects, models, etc, with respect to rules and regulations, the consideration instead of Anglo-Saxon Model and Code Checking activities.

In this discussion we will be providing some useful indications on a tool that allows users to address and perform a Clash Detection.
usBIM.clash is the first Italian software (certified by buildingSMART) in order to perform Clash Detection operations on IFC models and for the verification of interferences and conflicts managements, both on the models belonging to the individual disciplines and on federated models, or on the multidisciplinary model that includes all the models belonging to the disciplines involved in the entire project and its design process.

Clash Detection consists in checking the geometric interferences to identify those elements that collide with each other.

There are several types of clash detection or interference categories:
- Hard clash: elements that occupy the same physical space. This occurs when two objects are physically in conflict (for example, one element crosses another - a pipe that crosses a pillar);
- Clearance Clash: two objects are too close to each other such as to make assembly and/or maintenance impossible or difficult and this requires verification of tolerance spaces;
- Workflow Clash/4D: a temporal conflict that occurs when two objects of the building overlap during assembly, for example a very bulky element (which can't pass through door openings) and that threfore needs to be laid before the walls are raised. These conflicts are usually resolved during the implementation phase.

With usBIM.clash it is possible to have a clash detection for intersection (hard), a clash detection with tolerance distance/overlap (excludes collisions that are resolved by moving an element for a distance less than the specified length) and a clash detection with a minimum distance (clearance) (checks that between the elements there is at least a distance equal to that specified).

Furthermore, with usBIM.clash in addition to exporting the data of the detected interferences, in PDF, XML, HTML, CSV, XLSX formats, you can also export in the BCF format (BIM Collaboration Format vers. 1.0, 2.0 and 2.1).

The BCF format allows you to store the view and index of objects, so as to easily find the collision and read the data as an extra aid for support to designers.

The BCF format is an open format that allows BIM professionals to add text comments, screenshots and other information within the IFC model to ensure better communication between the various groups participating in project realization.

A compressed file that contains a folder for each identified interference/inconsistency. Within this archive there are 3 types of files that cover the transmitting of all relevant information useful for uniquely identifying the different problems that have been discovered.

These are:
- MARKUPS, i.e. a file that contains textual information concerning the IFC file with the model, the author of the report, the entities involved and the observations necessary to solve the problem;
- VIEWPOINTS, points of view that pinpoint the found problem directly on the digital model. They can be multiple and can be linked to the comments contained in the Markup;
- SNAPSHOT, images of the problem connected to the points of view identified within the digital model.

By opening the BCF file created with a third-party viewer, together with the relating IFC model(s), you will then be able to navigate step by step through the various Issues with the same method used in the native environment in usBIM.clash: interference names, author, camera point of view, notes and comments.

Watch the following videos to get a complete overview:
--->How to get working with usBIM.clash straight away
--->How to create Selection Groups
--->How to create Selection Filters
--->How to perform a Clash Detection
--->How to export in the BCF format

Best regards and enjoy working with usBIM.clash