ATENA

ATENA (Advanced Tool for Engineering Nonlinear Analysis) is a user friendly software for nonlinear analysis of reinforced concrete structures.

With ATENA one can simulate real behavior of concrete and reinforced concrete structures including concrete cracking, crushing and reinforcement yielding. ATENA gives the power to check and verify your structural design in a user friendly graphical environment.

The software has been extensively validated by winning predictions in various international benchmark competitions (such as Youtube video)

It is used at more than 1000 installations worldwide.

For more information, reach us at atena@xelastica.com.

Why Use ATENA

• It is to be used mostly for complex structures where considerations go beyond mere design codes.
• ATENA is for engineers interested in an in-depth understanding of the real structural behavior.
• ATENA is the perfect tool to assess reinforcement details in critical sections whose analysis may be problematic to other codes.
• The inherent nonlinear approach triggers internal force redistribution due to cracking; this may result in reinforcement savings.
• It helps to discover additional load carrying capacity.
• State of the Art tool used also by many researchers investigating the complex response of reinforced concrete structures or modern cementitious materials.

Merlin

Merlin is a proprietary specialized 3D nonlinear/transient finite element software which has been under continuous development by Saouma”s group to specifically address problems associated with: fracture and deterioration of concrete, safety assessment of dams and nuclear containment structure.
It is used in conjunction with its graphical based pre and post processors (Kumo and Spidr).

Development was made possible in great part through initial funding from the Electric Power Research Institute and then the Tokyo Electric Power Service Company ( TEPSCO).

Dynamic Analysis

• Time Integration: Implicit (Newmark, Hughes); Explicit (single CPU/Parallel).
• Restart: from Static (with dynamic elastic properties), Reset displacements to zero;
• Rayleigh Damping: Different coefficients for rock and concrete.
• Foundation: Mass but no gravity.
• Radiation damping: Without/with interaction with free field (Lysmer/Miura).
• Reservoir Modeling: Added mass (Westergaard, Zangar) or fluid elements.
• Uplift models: Automatic adjustment with crack propagation; Static (FERC) or dynamic uplift.
• “Validated” with centrifuge dynamic tests.

Nonlinear Analysis

• Algorithms: Newton-Raphson, Secant Newton, Initial Stiffness, Line Search, Arc-Length.
• Cracks/interfaces: Over 5 different types of interface elements. Smeared crack elements.
• Constitutive Models: Over 20 different models.
  • Kinematic model for expansion.
  • 3D AAR strain redistribution based on stress tensor.
  • Tensile strength and Young’s Modulus degradation.
  • Scalar Field Problems: Thermal (transient) steady state diffusion analyses.
  • Staged construction/excavation approximated.

PPACS

PPACS (Probabilistic Performance Assessment of Concrete Structures) is a library of Matlab-based scripts to facilitate risk assessment. Starting with a spreadsheet containing variables and their distributional models, and correlation factors, PPACS will generate a package of input files based on Latin Hypercube sampling for analysis with a generic finite element code.Following analyses, PPACS will data mine results for uncertainty quantification and sensitivity analyses. Final outcome is presented as Tornado diagrams, capacity and fragility curves and reliability indices.

PPACS can handle both epistemic (material and modelling) and aleatory (seismic and hydrologic loads) uncertainties. It benefits from advanced Machine Learning and Matrix Completion techniques to reduce computational load.