Finite Element Modeling for Structural Reliability Evaluations

Structural reliability is often evaluated with probabilistic based methods since variations can occur in the loading, material behavior, and composite structural performance over time.

The intent is to establish the probability that a structural condition could develop and then evaluate the risk relative to the cost for prevention. One application is life cycle costing to determine the optimal time for replacement of structures or components rather than continued maintenance costs and operational safety risk.

ANATECH, a Structural Integrity Associates company has performed numerous analyses in support of probabilistic based reliability evaluations for life cycle costing, including fatigue cracking at welded connections in miter gates, culvert valves, and tainter gates. In addition, extensive modeling and analysis were performed to address structural performance concerns because of concrete cracking due to alkali aggregate reaction. These analyses must establish a best estimate baseline performance using advanced, nonlinear analyses to simulate the true response. The limit states for structural performance are determined by projecting the best estimate response analyses in time. Response surfaces for probabilistic sampling are then characterized through a matrix of calculations for material and loading variations.

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Technical

 

Best Estimate Analyses for Performance Baseline

  • Establish best estimates for loading and materials

  • Design and evaluation of in-situ test data

  • Fluid flow modeling for hydrodynamic loads

  • Review of operational logs for event timing

  • Calibration of models with field data

Analytic Projections for Performance Limits

  • Fatigue cracking at welded connections

  • Joint deterioration under thermal cycling

  • Shear friction in grouted rock anchors

  • Section deterioration due to stress corrosion and flow erosion

  • Concrete deterioration due to AAR

  • Flow induced vibrations

  • Buckling under compressive loads

  • Cyclic degradation of rebar and grouted bar bonds

Develop Probabilistic Based Models

  • Evaluations for failure probabilities and life cycle costing

  • Determine limiting problem variables and range of variations

  • Construct structural response surfaces from matrix of calculations

  • Characterize response surfaces for interface with probabilistic modeling methods

  • Determine limit states for failure criteria in probabilistic analyses

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