Dr.-Ing. Johannes Will CAD-FEM GmbH/DYNARDO GmbH dynamic software & engineering GmbH

Transcription

1 Some necessities and obstacles for introducing sophisticated numerical analysis into Civil Engineering and Geomechanics Dr.-Ing. Johannes Will CAD-FEM GmbH/DYNARDO GmbH dynamic software & engineering GmbH

2 Sophisticated numerical analysis in Civil Engineering and Geomechanics use of general purpose FE-codes (ANSYS, LS-DYNA, ABAQUS,..or sophisticated Civil Engineering/Geotechnical codes (FLAC, DIANA, PFC, SBETA,.) including - non-linearity's (Material, Geometry, Status (Contact,..) - multiphysical effects (coupled thermal-fluid-mechanical) - 3 dimensional modeling - load history and limit load analysis - Stochastic (reliability) analysis for more realistic modeling of loading and resistance

3 necessary or asked for: design of constructions/buildings with important safety requirements to the society dams, bridges, skyscrapers, nuclear power stations, tunnels evaluation of risk potential according to terror attacks natural disasters (earthquake, flood,..) reassessment/ reconstruction of cultural heritage reevaluation/reassessment of existing infrastructure according to new standards/design codes modern design codes call for numerical methods

4 Obstacles / Barriers economical risks/effort Investment Software/Hardware training / practice to ensure necessary skills for successful use high economical risks when leaving best practice/state of the art high density of different design codes/standards use of sophisticated methods has to be defined in standards high verification effort ensuring intellectual control off different modeling phases verification of conservative character of all load/resistance assumptions acceptance from authorities sophisticated analysis has to be adapted to standards previous knowledge and practice (end up with necessary as well as additional work)

5 Obstacles / Barriers general purpose FE-code development is not focused to special Civil Engineering requirements material models including plasticity, damage, multiphysical effects (pore water pressure, ) extensions are partially available or could be implemented, but implementation and verification is expensive sophisticated engineering programs suffer from low cost software market low investments to code infrastructure (geometry, mesher, solver, elements, graphical user interfaces) to reach necessary physical/numerical power interfacing of different codes may become necessary ANSYS LS-DYNA, ANSYS-FLAC,.

6 Examples dynamic software & engineering GmbH

7 project target: close to reality coupled fluid flow mechanical analysis to - reduce operator risk & open up optimizing potential for the foundation Combination of ANSYS and FLAC 3D was used to exhaust today s available numerical power project schedule: 1. parameterized modeling with ANSYS 2. mesh verification with ANSYS 3. calculation of dynamic load signal from train passing with ANSYS (transient linear) 4. non-linear static analysis with ANSYS (Mohr Coulomb) 5. dynamic non-linear coupled fluid flow mechanical analysis with FLAC 3D - dynamic non-linear (Mohr-Coulomb) with stationary pore pressure - dynamic non-linear (Mohr-Coulomb) with in stationary pore pressure - dynamic non-linear (Double Yield Cap-Model) with in stationary pore pressure

8 mesh verification with ANSYS (wave propagation, Stress field) foundation profile 0-8 m Sand m Sand m Clay m Coal m dense Sand

9 calculation of dynamic load signal from train passing with ANSYS (transient linear) - driveway of TRANSRAPID spans over 60 m - calculation of load signal for middle driveway pillar - TRANSRAPD speed 450 Km/h -train loading (gravitational/breaking/ accelerating/centrifugal forces) modeled as moving loads -analysis for different damping values train position for maximum foundation load train leaving driveway

10 Non-linear coupled hydro-mechanical quasi static analysis of a transrapid train passage with elasticplastic material models (Mohr Coulomb) Plastic strain Total strain Failure of Yield criteria

11 Verification of cap material material models 0 to investigate: - soil consolidation Vertikalstauchung [-] dometerversuch Gemessene Werte Berechnete Werte - in stationary pore pressure effects - different loading/unloading modulus a cape material model double-yield from FLAC 3D was verified Axialdruck [Pa]

12 dynamic non-linear coupled fluid flow mechanical analysis with FLAC 3D - dynamic non-linear (Mohr-Coulomb) with stationary pore pressure (PP) - dynamic non-linear (Mohr-Coulomb) with in stationary pore pressure - dynamic non-linear (Double Yield ) with in stationary pore pressure total plastic deformation MC, stationary PP MC instationary PP DY instationary PP

13 elastic-plastic Masonry Analysis of the Church of our Lady in Dresden crack pattern Rüth (1939)

14 world largest masonry bridge Göltschtal Gemany parameterized geometry model verification of loading (dead loads, traffic, temperature, wind) verification of masonry material model (GANZ Swiss masonry standard) detailed geometry model with foundation, piles and arches made from granite, sandstone and masonry

15 displacement For the first time stability and survivability of the structure according to actual German standards (DIN/DS) was proven. plasticity stresses

16 A Geomechanics 2D/3D Stability analysis of dams -non-linear mechanical analysis -coupled fluid flow, thermal and mechanical analysis - elastic-plastic material models of rock, jointed rock, masonry, concrete, soil A Blick von der Wasserseite Verschiebungen in Talrichtung (cm) Dammsohle Schnitt A-A am linken Hang Plastische Vergleichsdehnung (Elementwerte) Dammsohle Blick von oben nur der Untergrund ist selektiert Verschiebungen in Talrichtung (cm) Blick von oben nur der Untergrund ist selektiert Plastische Vergleichsdehnungen (Knotenwerte)

17 Earthquake analysis of dams - often response spectra analysis is used - then quasi-static elastic-plastic analysis with worst case modal superposition is performed - with today's numerical power also nonlinear transient analysis is possible total deformation tension stress plastic strain

18 Geomechanics Foundation Analysis - non-linear load history - non-linear static and dynamic analysis - piles & plates

19 limit load analysis for airplane impact load modeling with RIERA load assumptions (area, pressure) shear damage of concrete shear failure of reinforced concrete structure

20 verification of the concrete model (plasticity & damage) uniaxial compression test The compression strength KN/mm2 and the damage mechanics was verified.

21 verification of reinforced concrete modeling (plasticity & damage) plastic concrete strain plastic steel strain The limit load and the damage mechanics was verified.

22 Airplane impact

23 Conclusion - physical and numerical power is available - interfacing of different programs still may necessary - effort to reach acceptance is high - we did successful project acquisition with authorities, insurances, private construction owners