Oregon DOTTraining MaterialPushover Analysis
Tanarat Potisuk, PhD, PE, SEPrestressed Concrete Standards EngineerBridge Engineering SectionOregon Department of Transportation
Introduction
Pushover Analysis (Nonlinear Static Procedure) required for SDC D
Pushover Analysis StepsStep 1 – Develop Pushover Analysis model
Step 2 – Define expected material properties
Step 3 – Define section properties
Step 4 – Define hinge properties and assign hinges
Step 5 – Run analyses (2)
Step 6 – Post processing
Step 7 – Determine displacement capacity for 1000 year and CSZE
Step 8 – Determine ductility index for each individual hinge
Step 1Use EDA aka. RSA 3D Model – delete superstructure
Step 1 (cont.)Set bent cap, columns, and foundation – consistent with EDA
Apply girder dead load reactions
Step 1 (cont.)Calculate analytical plastic hinge length
Step 2Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Dc = 72 in. Clr. = 2.5 in.Ds = 66.25 in.
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 2 (cont.)Define material properties, i.e. steel rebar, unconfined concrete, confined concrete
Step 3Define section properties
Step 3 (cont.)Define section properties
Step 3 (cont.)Define section properties
Step 3 (cont.)Define section properties
Step 3 (cont.)Define section properties – curvature unit = 1/in
Step 4Define hinge - global control
Step 4 (cont.)Set load cases
Step 4 (cont.)Define hinge properties
Step 4 (cont.)Assign hinges to elements
Step 5Push two perform analysis buttons
Step 6Observe deformed shape, bending moment and shear diagram, reaction
Step 6 (cont.)Observe pushover curve
Step 6 (cont.)Pushover hinge result – total deformation
One hinge and one section of 3
Step 6 (cont.)Pushover hinge result – plastic deformation
Elem 117 yields at Step 10
Step 6 (cont.)Find reaction, when columns all yield
Step 6 (cont.)Obtain Moment – Curvature data with selected column reaction
Step 7Establish strain limits per BDDM 1.17.3.1
1000-Year “Life Safety” – All Bridges in Oregon
CSZE “Operational” – All Bridges on and West of US97
Step 7 (cont.)Obtain section curvature (1/in) at strain limit
CSZE
1000 Year
Select 1st yielding Hinge
Step 7 (cont.)Obtain solution step to determine the corresponding deflection
Step 10 - 11
Step 7 (cont.)Obtain the deflection at the strain limit
~ 12 in
Step 8Determine member ductility index
Step 8 (cont.)Determine member ductility index
Only for 1000-year return period EQ
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