PEER/NEES Concrete Column Blind

Prediction Contest

Quake Summit 2010, NEES & PEER Annual Meeting, October 8-9

October 9, 2010

• 3D beam-column elements

• Moment-axial interaction

• Lumped plasticity at nodes

• ASCE 41 backbone curve

• ANSR-II for non-linear analysis

MODELING APPROACH

• Moment-curvature to verify: – Section response– Strain hardening– Failure mechanism

• Effective section properties:– SLS: 0.78Ig– ULS: 0.38IgPer NZS 3101: 2006

MODELING APPROACH

MODELING APPROACH

• Damping:– Based on original

stiffness– SLS: 2.0%– ULS: 2.5%

• Moderate unloading stiffness degradation: = 0.3

• Parameters that generally correlated well:– Displacement– Acceleration– Base moment– Shear force

… with some exceptions!• Displacements for record 5

were significantly different• Accelerations for records 3 &

6 were lower than predicted

PERFORMANCE PREDICTIONS

• Parameters that did not correlate well:– Axial force– Curvature– Axial strain

• Records 5 & 6 had the largest result scatter

PERFORMANCE PREDICTIONS

CONCLUSIONS & NEXT STEPS …

• Design office procedures in conjunction with ASCE 41 are capable of estimating global demand parameters with reasonable accuracy, on average.

• Macro modeling techniques are not well suited to capturing local member response:– Curvature– Strain etc.

• Tangent stiffness damping may be more appropriate for this type of structure

• With access to shake table test data, further improvement to these macro-modeling techniques can be expected