Featured post

Surfside Collapse Simulation | Champlain Towers, Miami, Florida

On the 24th of June 2021 at night the Champlain Towers South, a 12-story beachfront condominium in the Miami suburb of Surfside, Florida collapsed partially. This collapse simulation was made based on the presently available data, eyewitness, and video accounts.

This study demonstrates the collapse mechanism assuming the following plausible hypothesis: According to the data, the basement deck showed signs of extended soaking for many years. The problem was locally insufficiently patched and not rectified in its entirety. The wetting caused the deck ceiling to be weakened to such an extent that basement pillars punched through the deck where additional load had peaked at the planter area.

Main sources:





Featured post

Arecibo Observatory Collapse Simulation

This is a structural simulation of the collapse of the Arecibo Observatory in 2020. The simulation implements the three major failure events which ultimately led to the progressive failure causing the platform to fall into the dish. The simulation is based in part on actual physical data such as mass and strength for the larger components, and in part on plausible estimations. What appears to be multiple simulations at different points in time is actually one large global simulation. Deviations from reality are to be expected due to the fact that the simulation software runs completely autonomous, only the main initial failure points have been triggered by a predefined script. Nothing is animated by hand.

Failure history:

2020-08-10 Tower 4 auxiliary main cable north comes loose from the socket (#301)

2020-11-06 Tower 4 main quadruple cable south broke, one of four (#101)

2020-12-01 Tower 4 main cable total failure and collapse

Some stats for nerds:

Base 3D model – 1.87 million polygons Simulation model – 12,900 elements + 136k constraints Simulation time – ~16 h

Featured post

A hybrid simulation method of FEM and DEM

Researchers from the Tsinghua University, Beijing are suggesting a hybrid simulation approach that combines the accuracy of FEM and the speed of the BCB.

The article can be freely downloaded from here:

Abstract: Reliable and high-fidelity virtual ruin scenarios for collapsed buildings are essential for post-earthquake emergency search and rescue training. However, the existing research on the distribution of ruins caused by building collapse is insucient for supporting post-earthquake rescue training. Therefore, this paper proposes a hybrid framework for simulating building collapse and ruin scenarios, using a finite element (FE) model and a physics engine. Based on this framework, the following methods are proposed: (1) geometric model conversion from the FE model to the physics engine; (2) determination of the initial moment of collapse; and (3) data mapping of the FE
simulation results. In addition, a corresponding program, Finite Element Method to Rigid Body Dynamics (FEM2RBD), is developed for the hybrid framework. The proposed framework simulates the entire process of building collapse and the distribution of ruins. The accuracy of the framework is validated using a shaking table test of a three-story reinforced concrete frame. The collapse process and ruin scenario of a real-world library building is simulated as a case study. The results show that the proposed framework combines the advantages of the FE model during the small-deformation
stage with the advantages of physics engines during the large-deformation stage. The proposed framework can be valuable in simulating building collapse and ruin scenarios for post-earthquake rescue training.

Simulation of the Albiano bridge collapse

In the morning on the 8th of April 2020, the Albiano bridge in the region of Tuscany collapsed with only two vehicles on the road deck. The original bridge that was built in 1908 pioneered the construction of reinforced concrete bridges in Italy. The Venetian engineer Attilio Muggia designed the bridge with five slender arc structures spanning each ca. 52 m and four Pylons in the riverbed of the Magra river. The Pylons had strong vertical extensions that carried part of the road deck weight.


The bridge was damaged by mines in 1945 during the last days of the second world war. It was reconstructed after the war when building material was scarce, only the base of the pylons was reused. Instead of sufficiently dimensioned arcs, the new bridge design displayed arcs with tapering cross-sections at the bases, which were connected pairwise at opposite sites of each pylon. The tendency of low and wide-spanning arc structures to prolongate at the base was most probably not sufficiently considered, by offering enough resistance against horizontal forces. Furthermore, the debris of the broken arc bases appears to display little reinforcement iron this might be due to the material shortage at the time of the reconstruction. Stronger arc sections at the bases with more iron would have strengthened the structure.

We have simulated this collapse after careful analyzes of the image and video material that was posted online after the accident. This simulation assumes that material fatigue at the base of the second arc at the first Eastern pylon triggered the progressive collapse. This is a hypothesis that might help in the discussion to determine the reason for the collapse.

Our simulation method is based on the Discrete Element Method (DEM) that was developed during the EU funded INACHUS FP7 Project (607522) framework. It uses the open-source “Bullet Constraints Builder” addon for the 3D Blender software.

Details of the bridge: Material: Reinforced concrete Total length: 260 m (850 ft) Width: 7.2 m (24 ft) Height: 10 m (33 ft) No. of spans: 5 Pylons: 4 Date of original: 1908 Rebuilt: 1945–1949 Collapsed: April 8, 2020

The BCB in an art venue

We had a rare opportunity to apply the BCB in a high-level art project that is shown from December to March 2020 at the Helsinki Art Museum HAM.

This video shows impressions from the Nostalgia artwork by Jaakko Niemelä. For this project, the Virtual Validation Corporation was commissioned to simulate the destruction of a huge container ship and capture the different phases of its decay (Nostalghia). The simulation was done with Blender and the BCB Add-on.

Jakko Niemelä is a Finnish artist who has made destruction and the decomposition of structures an essential part of his art-making. During the past seven years, he traveled the oceans tracking his father´s routes who was a ship captain. Jaakko never really got to know his father and as a child often imagined the dangerous situations he might be in during his trips. With the Nostalghia project, Jaakko processes his fears and the relation to his father.

Nostalghia is shown from 14.12.2019-15.3.2020 at the Helsinki Art Museum, HAM. The installation at HAM displays a huge illuminated scaffold structure with sails that are blown by wind machines.

Also in this video, segments from the film “Lähtö – Departure” (the tree in the beginning)

Pedestrian Bridge Collapse in 2016, Kuala Lumpur, Malaysia | BCB Simulation

In 2016 a 70 meters long steel-truss pedestrian bridge has collapsed. We have simulated what happened. The bridge had an unusual design with the center of gravity lying outside of its own footprint. Increasing temperatures induced internal stresses that couldn’t be compensated by the bearings. As a result, the bolts of the bearings holding the bridge in place have been sheared off. Without any further restraint to the uplift load, the bridge had to topple and collapse. The half-completed pedestrian bridge to connect the KL Eco City to The Gardens shopping mall in Mid Valley City failed on Nov 29, killing one construction worker. We have been investigating this case by means of computer simulation to reproduce and visualize the collapse dynamics. Our virtual collapse simulations are based on real physics and represent the reality to a high degree.

Credits & Links: Virtual Validation Corporation: Kai Kostack, kostackstudio@gmx.de & Dipl. Arch ETH Oliver Walter,

Software: Laurea University of Applied Sciences LUAS, Finland Kai Kostack, Oliver Walter Blender: https://www.blender.org  Add-on: https://github.com/KaiKostack/bullet-..

Report on Model Enhancement and Validation Cases, comparison between AEM, FEM and DEM

Report on Model Enhancement and Validation Cases-extract,Inachus Deliverable D3.5

Report on Model Enhancement and Validation Cases-extract

Herewith we release to the public an extract of the Deliverable D3.2 “Report on Model Enhancement and Validation Cases” that was created in the INACHUS framework. This extract describes systematically simulation results that are based on our DEM method on component level to full building size – A paper that compares AEM and FEM  and that is based on the Deliverable D3.2 is available here:


Please contact us directly if you are interested in more details concerning the comparison of the three simulation methods.

Excerpt from the executive summary:
“The present deliverable deals with the in-depth analysis of three candidate simulation methods for the collapse and cavity prediction of single buildings within INACHUS: the Discrete Element (DEM), Applied Element (AEM) and Finite Element Method (FEM).

…The analysis of the maturity, predictive capabilities and efficiency of the three distinctively different methods is performed on three size scales – from component level to full building – and for two collapse threats – explosion and earthquake. ”

Final BCB release report

Bullet Constraints Builder (BCB) Final release report, Deliverable D3.5

Report on Model Enhancement and Validation Cases-extract

Herewith we release to the public the report that accompanies the final release of the Discrete Element based simulation software that was developed during INACHUS.

We have been contacted increasingly by interested parties to learn more about the principles and numerics behind our approach. This release will ease the access and deliver the requested information instantly.

The delivered software contains the Bullet Constraint Builder (BCB) which makes the simulation of collapse cases in conjunction with the open source software Bullet Physics engine and Blender possible.

Excerpt from the executive summary:
“This report documents the general approach of the Discrete Element Method, its speed optimized derivation and the functionality of the BCB. The development of the latter makes it possible to create simulation models from CAD models almost automatically and simulate the effects of devastating loading on a structure with simplified, but efficient models. Assumptions made and limitations of the approach are discussed. Possibilities for post-pro-cessing the results with special emphasis on USaR needs are given.”