Nonlinear Time History Analyses
Until the early 1990s, seismic design focused almost exclusively on the definition of design forces and moments based on response spectra analysis (RSA). The Loma Prieta Earthquake in 1989, followed a few short years later by the Northridge and Kobe Earthquakes, vividly demonstrated the shortcomings of this approach – particularly for concrete structures.
In highly productive collaborations with the California Department of Transportation and several engineering schools, ANATECH, – a wholly owned subsidiary of Structural Integrity Associates, developed new performance-based methodologies that allowed us to accurately predict, for the first time, the actual behavior of concrete and steel structures subjected to ground motions beyond their design basis. With unmatched expertise and state-of-the-art solutions, we have helped ensure the integrity of critical structures, from the Golden Gate Bridge to the Brooklyn Bridge – and beyond.
Many key structures in use today are considerably seismically deficient. Using the groundbreaking ANACAP-U concrete and steel analysis software system, we perform nonlinear analyses to identify seismic vulnerabilities and evaluate retrofit strategies to safely extend the lifetime of key infrastructure. Our specialties include the following:
- Seismic Design Qualification – Using linear response spectra methodologies that conform to regulatory guidelines, we perform analyses for the seismic design and qualification of nuclear-safety-related structural systems. Nonlinear time history analyses are employed if the RSA indicates that a slack rope condition can develop.
- Seismic Capacity, Ductility and Retrofitting – has a vast experience in determining the capacity and ductility of structures under seismic loading – particularly reinforced and prestressed containment systems and bridges – for both new designs and retrofits. These analyses involve highly nonlinear structural response models that track progressive and extensive damage leading to structural failure.
- Seismic Fragility – Using probabilistic methods with parameter variations, we can accurately determine the seismic fragility of existing structural systems.
We can applies the most current research and knowledge gained from recent events such as the Tohoku Earthquake and Tsunami and the 2011 Virginia Earthquake to continually improve our analytic software and provide cutting-edge structural engineering support services.
Using our advanced methodologies, we has provided unparalleled analytic support for the retrofit and replacement design efforts on many of California's largest signature bridges and performed seismic vulnerability studies of the Brooklyn and Queensboro bridges. Other applications include buildings, dams, intake structures and nuclear-safety-related structural systems, such as overhead bridge or gantry cranes and their supporting structures.
ANATECH, applies the most current research and knowledge gained from recent events such as the Tohoku Earthquake and Tsunami and the 2011 Virginia Earthquake to continually improve our analytic software and provide cutting-edge structural engineering support services.