Building Collapse Simulation under Dynamic Loading
Technical Article
The events of recent years remind us of the importance of earthquake engineering in seismic regions. For you as an engineer, the design of structures in earthquake prone areas is a constant trade-off between economic efficiency – the financial possibilities – and structural safety. If a collapse is inevitable, engineers must estimate how it will affect the structure. This article aims to provide you with an option on how to perform this estimation.
Using Dlubal Software, you can generate accelerograms and response spectra that are directly used in seismic analyses performed in the structural analysis program. The analysis is designed for avoiding structural failure in the context of the safety concept. What if a collapse occurs anyway? In this case, a collapse evaluation helps you to uncover weak points or to plan areas for protection. You can export any accelerogram from the extensive RFEM 6 library for such purposes to use it further.
However, there is even more. The structural model of your building structure is already available and can be used in other programs. This is where the different interfaces of Dlubal programs come into effect. Interoperability between structural analysis software and CAD programs is more important than ever. Exchange formats allow you to provide physical and architectural models for both software types. The goal is an intelligent building data model - the BIM model. Dlubal Software has many different interfaces. One of them is the IFC (Industry Foundation Classes) interface.
Now, you've got the 3D model and the acting accelerogram. And you are asking yourself if you can process this data to simulate a collapse?
The answer is yes! There is an add-on for Blender® that is able to model such a simulation using object properties called "constraints". The "Bullet Constraints Builder" (BCB) add-on allows such a simulation. My next article will explain in detail how to use the add-on.
To use the RFEM 6 data, an adjustment to the expected input format is necessary.
Adaptation of IFC for Blender® 2.79
Currently, the BCB add-on is only available for an older version of Blender® (2.79). To use the IFC efficiently in Blender®, we recommend installing the current version (3.5) and the installation of the BlenderBIM add-on.
1. Export the IFC model from RFEM 6.
2. Import the IFC model in Blender® 3.5.
3. Export the model as an .OBJ file.
4. Import the .OBJ file in Blender® 2.79.
Adaption of accelerogram for use in BCB
The BCB add-on expects an ASCII text file including comma-separated values (.csv) as input for the accelerogram. The setting is given by 4 columns (t [s], X [m/s²], Y [m/s²], Z [m/s²]). Lines beginning with # are skipped. To obtain this format, proceed as follows:
1. For example, you can load an accelerogram from the library.
2. Export the accelerogram to MS Excel.
3. Adjust the output according to the specification for BCB (4 columns: t [s], X [m/s²], Y [m/s²], Z [m/s²]) and save the file as .csv.
Using this data, you can start the collapse simulation in Blender®. My next article will explain in detail how to use the add-on.
Author
Stefan Hoffmann, M.Sc.
Product Engineering & Customer Support
Mr. Hoffmann is responsible for the development of the products for dynamic analysis, membrane structures, and RWIND. Furthermore, he provides technical support for our customers.
Keywords
Collapse Progressive Collapse BIM Earthquake Simulation IFC Excel Export
Downloads
Links
- Blender Website
- RFEM 6 / RSTAB 9 - IFC Export / Import
- Accelerogram from Library
- Step-by-Step Instructions on Collaps Simulation Using RFEM and Bullet Constraints Builder (BCB) in Blender
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The response spectrum analysis is one of the most frequently used design methods in the case of earthquakes. This method has many advantages, the most important being the simplification.
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Main Program
The structural analysis program RFEM 6 is the basis of a modular software system. The main program RFEM 6 is used to define structures, materials, and loads of planar and spatial structural systems consisting of plates, walls, shells, and members. The program can also design combined structures as well as solid and contact elements.
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