Category Archives: blender

Simulation of WT7 with the BCB

The BCB has delivered valuable results when it was used to simulate the
destruction of the Pyne Gould Corporation building in Christchurch and
the collapse of the apartment block in Chennai. Both cases have been
described in this blog earlier. Now, a third collapse simulation comes
along as another validation case, it further emboldens us to believe
that the BCB delivers noteworthy results. Kostack studio used the BCB to
simulate the collapse of the World Trade Center 7 that occurred after
the terror attack in New York in 2001. This collapse is still furiously
disputed to prove or disprove conspiracy theories that claim that the
collapse happened by controlled demolition. Kostack studio procured the
detailed construction drawings  and built an accurate model
with all relevant structural members in Blender. For the initiating
collapse event the findings of the NIST (National Institute of Standards
and Technology) investigation report were used. According to this report
the failure occurred due to the intense fires that were triggered by the
debris from the other two towers. The sprinkler system in WTC7 did not
work properly. The fire caused the thermal expansion of steel beams that
caused a girder to slide and loose its bearing which in turn caused a
vital pillar (column number 79) to buckle. In the Blender model column
79 was removed.

The load bearing structure of the WTC7 was made of steel. The steel
members were bonded with screws. To replicate these connections the
strength formulas in the BCB perform a rough approximation of the ratio
of the total screw area section and member contact area.

The Blender simulation replicates a peculiarity that is not evident when
watching the actual video footage from the collapse. The building’s
structure was a typical tube-frame design, the facade columns and beams
formed a rigid frame that delivered a strong structural membrane along
the exterior of the building. After the implied column failure the
structure collapsed from within and left the hollow membrane staying for
a while before the latter was caving in on itself as well.

This simulation is a sober re-creation of the alleged damages caused due
to the fires that were stated in the NIST report. It is not meant to
comment on any of the claims regarding the conspiracy theories.

WTC7 technical drawings:
http://www.911datasets.org/index.php/NIST_WTC7_FOIA_09-49
http://www.911datasets.org/index.php/NIST_WTC7_FOIA_11-209
http://www.911datasets.org/index.php/NIST_WTC7_FOIA_12-009

 

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Second pilot in France

The second INACHUS field test was held on 31 May 2017 in Lyon, France. It focused on

merging data from wide area assessment tools and collapse simulations. In collaboration with

CARDEM, a French demolition company, INACHUS partners identified a three-storey factory

building in Saint-Fons that was scheduled to be demolished. A first scenario planned to weaken

key pillars and subsequently pull the building over by ropes. It then was decided to execute a

second scenario by gradually weakening certain pillars until collapse occurred, this procedure

was designed to mimic the impact of an earthquake.

Factory before and after collapse. Pillars were progressively weakened until collapse occurred

ASI visited the building in spring to record the construction technique in order to build the

virtual building model. The model was then simulated by ASI with the second collapse scenario.

Ground-based and airborne laser scans by FOI, ONERA and ITC created a textured point cloud

model of the building before and after the collapse. The image below shows the matching of

laser scan and simulation result.

The matching of laser scan and simulation result by ASI.

The Video below shows the simulation result performed by LUAS. The DEM model (provided by

courtesy of ASI) was simulated by applying the first collapse scenario where some pillars were

weakened and where the building was  then pulled over by ropes.

The Vitruv Building Library

In order to supply rescue personnel with training material  a data base with pre-run collapse simulations was created. This building library consists of four building types that are archetypical representations of a number of commonly built structures:
1. Vitruv Building #2: a low apartment building
2. Vitruv Building #3: a high rise building with a square shaped floor plan and a center core
3. Vitruv Building #9: a high rise building with a rectangular floor plan and a center core
4. Vitruv Building #11: a historic, double wing brick building

Those four buildings have been submitted to various explosion and earthquake scenarios. Damages from detonations were defined and earthquakes with four ascending intensities from low to devastating were simulated.

This building library is expected to be extended in the future to not only serve training exercises but also allow more and more accurate predictions where hollow spaces will be formed in which victims can survive.

In the beginning the videos show a new useful BCB functionality: A mesh of the concrete rebar is generated following the definitions in the BCB´s Formula Assistant namely rebar position amount and sizes. This rebar mesh is only for diagnostics to detect obvious mistakes in the element settings and is not linked to the simulation routine.

We picked up our initial approaches (blog post from 20. Mai 2015) to visualize cavities and applied a modified version on the collapse debris mesh. We could prove that cavity can be visualized fast and directly  in Blender largely with Blender´s native inbuilt modifiers. The result can be seen in the last sequence of the videos.

Another simulation for the building library

This video shows the simulation of the second building from the building library. Two damage scenarios were examined: a pillar removal due to explosion and an earthquake. The pillar removal did not lead to collapse. The video displays the reaction when the strong earthquake time history was applied.

The building library collects a range of typical building structures (9-10 buildings) including structural details. Prone to collapse risks are examined and the collapse shapes are exported from the simulations in a digital exchange format DXF and OBJ. The building library can be used in a real collapse case to estimate the probable location of cavities.

building-9-pillars

The removal of these two pillars did not lead to collapse.

 

Urban Search and Rescue virtual training tool prototype

Here is a video and download link for the virtual training tool prototype created using Unreal Engine 4. The building model is from a collapse simulation of the Pyne Gould Corporation building in Christchurch, New Zealand. The simulation was made by Laurea UAS as a part of  INACHUS´ software validation cases .

Download link:

https://1drv.ms/u/s!An_aRlulJVbggsllAar-_uxE9uMZhA

At the current stage of the prototype, the user will try to find and evacuate all victims in the scene. The prototype will hopefully be improved further by another student, so it can be brought to a point where it could be used as a virtual training tool to reduce costs in Urban Search and Rescue training. For example adding first aid, techniques and decision making according to the USaR principles could be implemented in the tool.

The project was done by Ville Tiira as an internship and thesis, which are a part of the Bachelor’s degree in Business Information Technology in Laurea UAS.

 

Simulation of an extraordinary building collapse in Chennai, Moulivakkam, India

On 28th of June 2014 around 4:40 PM IST one of two under construction buildings collapsed at  a suburb of Chennai, in the Indian state of Tamil Nadu. The collapse happened during heavy rain and a thunderstorm with lightning. The building site was still busy. Workers and casual uninvolved searched shelter from the rain and frequent lightning. This is the reason  the accident claimed many victims, altogether 61 casualties. Many of the survivors delivered eye witness reports. According to those reports the building collapsed directly after a lightning stroke. This might be the first documented case where a lighting caused the complete collapse of a building.

The debris pattern is most unusual, since the building was split into two halves and each half shifted to the respective side. The simulation, made by Virtual Validation Corporation Kostack & Walter, reproduces this extraordinary dynamics very well. The software was developed at Laurea University of Applied Sciences.