Leo Frigo Bridge Collapse Emergency Pier Analysis & Repair Image Courtesy of: Image Courtesy of: NBC 26 Presented by: John Zuleger

Collapse Event September 25, 2013 reports of sagging bridge to 911 Video Courtesy of: greenbaypressgazette.com

WHAT HAPPENED? Pier 22 sank approximately 2 feet Highly corrosive soil accelerated pile deterioration causing failure Microbially Influenced Corrosion (catalyst) Macrocell corrosion (electrochemical between soil strata) Buckled Pile at Pier 22 Image Courtesy of: WDP & Associates

Location Green Bay, WS: I-43 over the Fox River Image Courtesy of:

Bridge Description *22* * Sunken Pier – Immediate Repaired Pier – Tier 1 Investigated Pier – Tier 2 Type: Ties-steel arch Opened: 1981 Total length: 1.51 miles

Tier 1 Analysis Piers for Immediate Analysis and Repair

Pier 22: Settled ~2 feet Temporary support truss placed to stabilize structure Tier 1 Analysis Piers for Immediate Analysis and Repair

RC Pier used to model 60” caissons Existing HP 14x73 piles modeled as control Additional 40% dead load due to deflection. Snow also considered due to no removal available ~30-50 kips/bearing. Pier 22 – 60” Caisson Pier 22 – Existing Piles Tier 1 Analysis Piers for Immediate Analysis and Repair

POST- TENSIONED BARS BUTRESSES 7’-6” FOOTING EXT. Repair Plans

Repair Construction

Piers 12, 13, 14, 18, 19, 20, & 39 considered for service life analysis Tier 2 Analysis Tier 2 Piers for Service Life Investigation

Pier 12 Pile Layout Pier 13 Pile Layout Tier 2 Analysis Tier 2 Piers for Service Life Investigation

INVENTORY VS. OPERATING RATING Typically inventory and operating ratings for superstructure Ratings investigated and adjusted for substructure due to transient loads, 300kip initial geotech pile capacity DOT specified operating rating used for investigation RatingFactorPile capacity (36ksi*21.4in 2 )/Factor Operating kip Inventory kip Geotechnical2.12/1.7 = kip # Note: 300k * 2.12/1.7 = 375k Tier 2 Analysis Tier 2 – Capacity Factors for Analysis

Pier 12 RC-Pier 3-D ModelPier 12 RC-Pier Structural Model RC-Pier models developed to provide reactions at the base of the columns for pile loads Dead, live, and transient loads considered. Tier 2 Analysis Tier 2 – Load Reactions for Piers for Service Life Investigation

Model Limitations: Geometry of column slant for induced moment Conclusions: Taller piers require induced moment at base of column due to slant. Pier height varied from ~ 55’-90’ CADD Model Used to Determine CG of Footing for Slant Offset Moment FEM Model, Legs Straight Tier 2 Analysis Tier 2 Piers for Service Life Investigation

Model Limitations: Frame action Conclusions: STADD models used to determine frame action effect negligible with straight & slanted columns Tier 2 Analysis Tier 2 Piers for Service Life Investigation

Objective: Explore pile failure mechanisms as piles exceed operating limits due to increased section loss and zippering effect occurs. Cases Investigated: 1)Adjust pile group section loss to failure, no redistribution 2)Adjust individual piles to failure, remove failed piles, redistribute load, continue until pile group zippering effect occurs (50% & 100% axial capacity of failed pile retained) 3)Adjust section loss to failure for local buckling criteria, no redistribution 4)Adjust section loss to failure for local buckling criteria, remove failed piles, redistribute load, continue until zippering effect occurs (50% & 100% capacity of failed pile retained) 5)Compare structural section loss analysis to geotechnical corrosion analysis estimating remaining service life FLANGE WEB Tier 2 Analysis Tier 2 Piers for Service Life Investigation

Service Groups I, V, &VI further investigated Service I typically controlled for shorter piers Tier 2 Analysis Tier 2 Piers for Service Life Investigation

Service Groups I, V, &VI further investigated Service I typically controlled for shorter piers Local Buckling Criteria Sheet Section loss adjustment Tier 2 Analysis Tier 2 Piers for Service Life Investigation

My Mx Pz Zippering Simulation for Cases 1 & 3 No Redistribution Tier 2 Analysis

Example of Results: Pier 13 Global Pile and Local Buckling with No Redistribution Tier 2 Analysis

My Mx Pz Zippering Simulation for Cases 2 & 4 Allowing Redistribution Tier 2 Analysis Although buckled, pile retains some capacity

Example of Results: Pier 13 CG of failed pile shifted to center of pier therefore no moment capacity, 50% or 100% axial capacity remained Simulates failure of pile but possible retention of capacity after failure (see below) Global Pile and Local Buckling with Redistribution with Retention of 50% & 100% Capacity Failed Pile at Pier 22 Tier 2 Analysis

In situ condition of piles Tier 2 – Corrosion Analysis Pier 39NW – Tier 2 PierPier 21NW – Tier 1 Pier Tier 2 Analysis

TIER 2 – CORROSION ANALYSIS Typical baseline corrosion established for 35 year service, 5% total section loss Future baseline corrosion growth by 0.14% per year Pile specific pitting area added to baseline for starting point Future pitting growth per year applied to initial measured pitting area Total future predicted percent section loss compared to section loss causing failure from zippering analysis Corrosion analysis to predict future section loss of piles comparing to zippering analysis to determine remaining service life Tier 2 – Corrosion Analysis Tier 2 Analysis

Based on structural (zippering) analysis, 45% is approximate flange section loss causing first failure 45% section loss achieved at year 50 for Pier 13 Inch/year Tier 2 – Corrosion Analysis Tier 2 Analysis

Questions Thank You!