Combining semantic 3D GIS with numerical Simulation for assessing the impact of Blasts in urban...

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Combining semantic 3D GIS with numerical Simulation for assessing the impact of Blasts in urban Environments

Coupled Problems 2015

Venice

Arne Schilling Stefan Trometer

virtualcitySYSTEMS GmbH CADFEM GmbH

Berlin, Germany Grafing, Germany

Arne Schilling, Stefan Trometer 2

What is Urban Simulation?

Challenge

Use Case: Simulating Explosions in Urban Environments

Discussion

What‘s Next?

Outline

3 Arne Schilling, Stefan Trometer


Simulation of physical phenomena in urban environments using virtual mockups / 3D city models



Mechanical simulations of building structures

Acoustic studies / blast simulations

Wind field simulations

Simulation of flood events

…


GIS is not designed for performing complex physical computations • Strengths of GIS are data management, spatial analysis and visualization

• 3D city models are created using remote sensing and automatic feature extraction methods, not using CAD software

Challenge


Challenge



Physical simulations are frequently done in product design • Using Cumputer Aided Design (CAD) and Computer Aided Engineering (CAE)

software such as ANSYS

• Based on the Finite Element approach -> Numerical Simulation


Challenge



Physical simulations are frequently done in product design • Using Computer Aided Design (CAD) and Computer Aided Engineering (CAE)

software such as ANSYS

• Based on the Finite Element approach -> Numerical Simulation

Technological gap between GIS and CAE Worlds • CityGML cannot be loaded by CAE software (e.g. ANSYS). Geometrical

representations are very different -> we need conversion tools

• Requirements on data quality are different

• Simulation results are mostly stored in proprietary formats


Challenge

Create a workflow from 3D Geographic Information Systems to Simulation frameworks and back



Safety perimeters (red: evacuation, blue: curfew)

Unexploded Bombs from WW2

Frankfurt a.M. 2013 (150 kg)

Recovery of defused bomb

Disposal of defused bomb



First assessment in 3D city model using damage zones and perimeters based on lookup tables


Simulation of shockwave propagations in ANSYS

• Extracting 3D city model from a CityGML database

• Geometry processing, geometry healing for creating solid models


Geometry healing, e.g. removing inner surfaces (top) and resolving self-intersections (bottom)



• Importing 3D city model using STEP (AP 214)

• Setting up rigid volumetric objects (for buildings and for the ground) as Finite Elements


3D city model in ANSYS Finite Elements generated from 3D city model



• Setting up air space as Euler grid (grid space 0,5m – 1,0m)

• Setting up spherical explosive charge and physical properties (e.g. air density, materials)

• Using explicit solvers (AUTODYN, LS-DYNA and APOLLO from Fraunhofer EMI) to run the physical simulation


Air space as Euler grid shockwave propagation in ANSYS



• 1D simplification to speed up computations within the first meters until the shockwave hits a building

• Computation time hours - days

• Analysis within ANSYS


Time stamp in APOLLO Reading points, grid refinement



• Export simulation results as 3D grid data sets for several result types:

Single time stamps

Peak overpressure

Impulse values

Damage indicators for glass, masonry, injuries based on pressure and impulse values

• Create 3D models that can be used in online portals

-> important for decision makers


Triangulated model for visualizations Results in online portal


Scenario 2: 34 ms


Scenario 2: 84 ms


Scenario 2: 168 ms


Scenario 2: 335 ms


Scenario 2: 503 ms


Scenario 2: 670 ms


Scenario 2:

Peak Overpressure


Scenario 2:

maximum Impulse


Scenario 2: Damage

Categories


Scenario 2: Quick

Assessment


Gefahrenkarte Szenario 2

Scenario 2:

Indicator Glass



Scenario 2:

Indicator Masonry



Scenario 2:

Indicator Eardrum


Discussion

Model Quality • CityGML LOD 2 city models (no windows, balconies etc, roof

information)

• Simulated area limited to 1x1km (limitation in ANSYS)

LOD2 model of Berlin Simulation with LOD3 model

Super-detailed simulation


Discussion

Comparison of AUTODYN, APOLLO and LS-DYNA solvers • Computations in AUTYDYN and LS-DYNA took 3 days

• Computations in APOLLO took 3 hours


Discussion

Sensitivity analysis • Increasing the robustness of results

• finding a reasonable grid size for modelling the air space -> ca. 1m


What‘s Next?

Gefahrenkarte Szenario 2 Simulation of pedestrian comfort levels

• CFD Methods for simulating

• Exchange of 3D city models using STEP

• Output: velocity plots at pedestrian level (wind comfort analysis)

Thank You Arne Schilling Stefan Trometer

virtualcitySYSTEMS GmbH CADFEM GmbH

[email protected] [email protected]

http://www.virtualcitysystems.de http://www.cadfem.de

Combining semantic 3D GIS with numerical Simulation for assessing the impact of Blasts in urban...

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