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Civil & Environmental Engineering Session: Bridge Survivability under Extreme Multi-Hazard Loading Dynamic Response of a Large-scale Prestressed Concrete Girder Bridge Subjected to Hurricane Wave Forces Thomas Schumacher, University of

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Dynamic Response of a Large-scale Prestressed Concrete Girder Bridge Subjected to Hurricane Wave Forces

Thomas Schumacher, University of Delaware Christopher Higgins, Oregon State University Christopher Bradner, Naval Surface Warfare Center Carderock Division Daniel Cox, Oregon State University Presented on Monday, April 4, 2011 Session: Bridge Survivability under Extreme Multi-Hazard Loading ACI 2011 Spring Convention, Tampa Bay, FL Civil & Environmental Engineering

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Overview

Source: Douglass, University of South Alabama / Google Maps

Bridges damaged during hurricanes in 2004 and 2005

I-10, Lake Pontchartrain US 90, Bay St. Louis US 90, Biloxi Bay I-10, Mobile Bay I-10, Escambia Bay

FL AL MS LA

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I-10 Bridge over Escambia Bay, FL

Source: Pensacola News Journal

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US 90, Biloxi Bay Bridge, MS

Source: Douglass, University of South Alabama

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Background

Project task: Determine forces on bridge superstructures due to

hurricane waves, develop methods to estimate forces

Large-scale test, 1:5
Bridge model with realistic details and

properties

Tunable lateral support system

(rigid, dynamic, unrestrained)

Direct measurement of reaction forces
Interdisciplinary research team from Coastal & Structural Engineering

Photo courtesy S. Yim, OSU

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Why testing?

Past research:
Off-shore structures not valid for coastal bridges!
Equations to estimate forces for piles, vertical walls, flat slabs
Small-scale experiments, scale of 1:50 to 1:8
Integration of local pressure measurements to get overall forces
Realistic structural behavior neglected (no substructure flexibility)
2008 AASHTO guidelines need verification:
equations based on rigid substructure configuration
no guidance on how overall forces are distributed to girders

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How to model realistic bridge behavior

SWL

Cross section of typical bridge

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6 AASHTO Type III girders, 4 diaphragms

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Span length = 11.3 ft (56.7 ft)

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Total weight = 4034 lbs (504 kips)

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Assembled test setup

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Tunable lateral support system

Phase 1: quasi rigid Phase 2b: soft springs Phase 2a: medium springs

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Elevation view test setup

Vertical load cells Horizontal load cells Accelerometers Displacement sensors

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O.H. Hinsdale Wave Research Laboratory

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Regular and random waves (T = 2.0 to 4.5 s)
Hurricane Katrina conditions (H = 1 to 3 ft)
Water height (SWL)
Structural parameters
3 substructure flexibilities
With/without guard rail
Unconstrained
Data set of ~400 test trials

Overview of Experiment

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Experimental Data

All data for dc = 0 (water level even with bottom line of girders)
Pressure vs. force measurements
Maximum reaction forces
Horizontal reaction forces: rigid vs. dynamic substructure
Reaction forces vs. wave height (correlation plot)
Rigid vs. dynamic response
Comparison with 2008 AASHTO guidelines
Show time!

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Pressure vs. force measurement

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Maximum reaction forces

d* Horizontal Force (kN) Vertical Force (kN)

0.5 1 1 5 2 10 3 15 4 20 5 25 Weight of bridge span H = 0.6 m, T= 3.0 s Horizontal Force, Fh Vertical Force, Fv

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Horizontal reaction forces: rigid vs. dynamic setup

Horizontal force (rigid) Horizontal force (dynamic)

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Reaction forces vs. wave height (correlation plot)

Incident wave height, Hin [m] Incident wave height, Hin [ft] Horizontal force, Fh [N] Horizontal force, Fh [lb] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0

4000
2000

2000 4000 6000 8000 10000 12000

250 750 1250 1750 2250 Regular waves, T = 2.5 s Rigid setup Flexible setup Incident wave height, Hin [m] Incident wave height, Hin [ft] Vertical force, F v [N] Vertical force, F v [lb] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

12000
6000

6000 12000 18000 24000 30000 36000

2500
1000

500 2000 3500 5000 6500 8000 Regular waves, T = 2.5 s Rigid setup Flexible setup

Horizontal reaction forces Vertical reaction forces

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Comparison with 2008 AASHTO Guidelines

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Comparison with 2008 AASHTO Guidelines

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Movie 1: Phase 1 (rigid setup)

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Movie 2: Phase 2b (soft springs)

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Movie 3: Phase 3 (unconstrained)

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Ongoing and Future Work

2008 AASHTO guidelines:
Verification of predictions
Guidance on trapped air factor TAF
Extension of equations for flexible

substructures

Research on Tsunami loading of bridges

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Thank you for your attention!

Civil & Environmental Engineering

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Publications

Schumacher, T., Bradner, C.; Higgins, C.; Cox, D.; Wave Forces on

Bridge Superstructures: Large-Scale Laboratory Observations and Comparison with AASHTO Guidelines; in preparation.

Bradner, C., Schumacher, T., Cox, D., Higgins, C.; Experimental Setup

for a Large-Scale Bridge Superstructure Model Subjected to Waves. ASCE Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 137(1), January/February 2011, pp. 3–11.

Schumacher, T.; Higgins, C.; Bradner, C.; Cox, D.; Yim, S.; Large-Scale

Wave Flume Experiments on Highway Bridge Superstructures Exposed to Hurricane Wave Forces; Proceedings of the Sixth National Seismic Conference on Bridges and Highways (6NSC); Charleston, SC; July 27– 30, 2008.