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, & Dipl. Arch ETH Oliver Walter,

Software: Laurea University of Applied Sciences LUAS, Finland Kai Kostack, Oliver Walter Blender:  Add-on:

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.”

Simulation of a shake table test

LUAS replicated a shake table test experiment that was conducted at the University of Auckland to study the resilience of typical local masonry structures and the improvements by retrofitting measures. Blender and the BCB was used to remodel the shake table structure and expose it to the same seismic pattern that was used in the laboratory. This test showed interesting affinities but also deviations that are hoped to be addressed in a future joint cooperation. Discussions are going on how Auckland can contribute their distinct knowledge in masonry dynamics and to implement simplified strength formulation. This would extend the functionality of the BCB to enable the simulation of masonry building in addition to concrete structures. Eventually Blender and the BCB could be used to efficiently simulate the effects that a major earthquake has on large historical neighborhoods.

The collapse of the Morandi bridge

On August 14 the Morandi bridge in Genoa collapsed partially. A 200
meter long roadway section fell 15 meter on the below apartment houses.
In the course one of the massive pylons collapsed as well. The tragedy
claimed the lives of 43 people. This bridge was part of the A10 motorway
that is the main link between the Italian and French riviera. This
accident is one of the big tragedies that come unexpectedly and live
long in our memories. It it makes us ponder over the safety of similar
old structures that eventually would need urgent repair.

The reason of the collapse of the Morandi bridge is currently hotly
debated. Much hints to a lack of maintainance and a resulting failure of
structural member. But also the heavy weather conditions with a
Thunderstorm and a lighting impact are often blamed.

Most theories point to the failure of one of the suspension cables. The
BCB was used to systematically analyze the presumed collapse episode and
debris shape for the failing of each of the four suspensions. The
simulations were performed by Kostack Studio.

Hands-on exercise with end-users

During the exploitation and dissemination Workshop at the training Campus Weeze from 16.-17. April 2018 LUAS presented the BCB to end-users. The program was distributed to the visitors on give-away memory sticks. The end-users simply moved the content of the memory stick to a folder on their laptops or Mac´s (The BCB works cross-platform) and started Blender (the Fracture Modifier including BCB) directly, because no installation is needed. First we presented the simulation process step-by-step on a simple structure. Then the end-users were invited to open and simulate a prepared model of the H-shaped rehearsal building at the Weeze site . It was nice to see an Inachus partner with Blender experience to be engaged in own simulations from scratch after our presentation.

This video shows the simulation of the H-shaped rehearsal building at the Weeze site under an earthquake event. It is a processed simulation that includes the distribution of dummies. This feature is new in the BCB and was implemented after the pilot in Weeze. The distribution of large amount of human figures is made with the help of Blender´s particle system, a new preset group ‘Victims’ has been added in the BCB element groups for this purpose. Note, that the simulation of masonry structures is not yet sufficiently studied and the simulation results still may lack plausibility.