SHRP2 Project R04

Everyday Solutions: ABC Designs from SHRP2

Bala Sivakumar

HNTB Corp.

Introduction

Many deficient bridges in the US are in need of replacement

Minimizing traffic disruption is a

priority

Most of these are routine structures

Need for standardized solutions to deploy successful ABC technologies

Systems that are easy to construct and

adaptable to many sites

SHRP2 Project R04 PROJECT GOAL

To develop standardized approaches to designing, constructing, and reusing complete

bridge systems that address rapid renewal needs

Phase I – Define ABC Challenges

Phase II – Identify & Refine the Best ABC Technologies

Phases III & IV – Standardize & Deploy ABC

SHRP2 Project R04

INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL

2008 -- 2013

HNTB (Prime) Iowa State University

Structural Engineering Assoc.

Genesis Structures

Dr Monica Starnes, Senior Program Officer SHRP2

Accelerated Bridge Construction (ABC)

Prefabricated Elements

Modular Construction

Structure Placement Methods

Accelerated Geo-tech Work

ABC ELEMENTS & METHODS

SHRP2 R04 -- Phases I, II, III (2008 – 2011)

Phase IV (2011-2013)

This presentation is on first 3 Phases

ABC elements and modular systems

SHRP2 R04 ABC Toolkit

Expected Outcome: The designer, guided by the standard plans, details and the set of ABC design examples will be able to easily complete an ABC design for a routine bridge replacement project.

1 ABC STANDARD PLANS

2

3

4

ABC DESIGN EXAMPLES

ABC ERECTION CONCEPTS

5 ABC CONSTRUCTION SPECIFICATIONS

ABC DESIGN SPECIFICATIONS (LRFD)

First Demonstration Project Demonstrate Use of ABC Standards Developed

in SHRP2 R04 Keg Creek Bridge, Iowa

– Total prefabricated bridge (PBES)

– ABC standard plans & details developed in SHRP2 R04 Project were used with minimal customization for the site

14 day ABC period

Opened Nov 1, 2011

Feb 16 ABC Webinar

ABC Standard Plans

• Focus on “workhorse’ bridges

• Complete bridges using prefabricated elements and modular systems

• Contractor could self-perform a lot of the work

• Simple to fabricate on site or in a plant and easy to erect using conventional cranes

• Fast assembly in the field in 1 to 2 weeks

• Durable connections / durable bridges

GOALS:

Outline of ABC Standard Plans

Standard Sheet Sets Contents

G1 – G3 General Information Sheets

A1 – A12 Precast Abutments, Wingwalls, & Approach Slabs

P1 – P9 Precast Complete Pier Systems

S1 – S8 Decked Steel Girder Superstructures

C1 – C12 Decked Concrete Girder Superstructures

CC1 – CC32 ABC Erection Concepts

Span Ranges for Superstructures • Simple / continuous spans from 40 ft to 130 ft.

• Simple for DL ; Continuous for LL ; No Open Joints

• Plans are grouped in the following span ranges:

– 40 ft to 70 ft

– 70 ft to 100 ft

– 100 ft to 130 ft.

• Spans to 130 ft can usually be transported and erected in one piece at many sites.

• Weight < 200 Kips for erection using conventional cranes commonly used by contractors

• Some ABC standards can be adapted to spans < 40 ft

Modular Superstructure Systems

Deck Bulb

Tees

Double

Tees

Composite

Steel

System

2 Lane bridge with shoulders shown – customize width for site

Typical Decked Steel Girder Module Interior

• Not proprietary

• Contractor can self-perform precasting of deck onsite

• Lightweight system for ABC

Decked Steel Girder Module Exterior

• Barrier can be precast

• Barrier load on exterior module

Prestressed Decked Girders

Based on the PCI NEXT

beam

Spans to 90 ft

Low depth alternative

Deck Bulb Tee

Span lengths from 40 ft to 130 ft

UT, WA, ID among states with DBT

standards

ABC Standards for Substructures

ABUTMENTS & WINGWALLS

– Semi Integral Abutments

– Integral Abutments

– Inline or U type Wingwalls

– Pile Foundation and Spread Footing Options

COMPLETE PIERS

– Precast Conventional Pier

– Precast Straddle Bent

– Drilled Shaft and Spread Footing Options

Integral and Semi-Integral Bridges for

Rapid Renewal

• Well suited for ABC

• They allow the joints to be moved beyond the bridge

• Close tolerances required when utilizing expansion bearings and joints are eliminated

• The backwall is precast with the deck.

• Fast erection in 1 to 2 days, economical

Semi-Integral Abutment Suspended Backwall

• H piles or spread footings • Fill pile pockets with SCC • Easy fit-up in the field

Integral Abutment

• Only one row of vertical piles • Precast backwall - dowelled • Fast construction

Precast Approach Slab Precast Sleeper

Slab

• Flooded backfill

• Flowable fill under slab

• Exp joint can be moved to

sleeper slab

Complete Precast Piers

Conventional Pier

Straddle Bent

• Deep foundation may be outside existing footprint

• Non-prestressed so contractor can self-perform precasting

• Fast erection using grouted splice couplers

ABC Connections • Connections affect field assembly time.

• Goal is rapid field assembly and long-term durability of joints

• Also, flexural continuity between modules to emulate CIP construction

• Connections affect seismic performance

• REFERENCE: FHWA Connections Manual

Connections for ABC

– Ultra High Performance Concrete (UHPC) longitudinal & transverse joints between superstructure modules

– Grouted splice couplers in piers replace the typical lap splice

– Self Consolidating Concrete (SCC) pile connections and abutment to wingwall connections

……………………………………………………………………………………

– Grouted cap pockets / grouted ducts for substructure connections (seismic)

– Other rapid set concrete options may be used

Grouted Splice Coupler

• Allows rapid construction. No post tensioning required • UHPC joints are typically 6 in wide. Good durability • Can be reinforced with hairpin bars or straight bars

UHPC Joints in Bridge Deck

(Longitudinal Joint.

Longitudinal steel not shown)

Transverse UHPC Joint in Deck Iowa Project: First use in the US for UHPC Trans. Joints

• Simple for DL -- Continuous for LL

• UHPC joint carries the full LL tension

• Tie plates transfer compression

Lab Tested at Iowa

State University

Erection Concept Drawings • Erection using conventional cranes.

• Erection using ABC construction technologies adapted from long span construction

Organization of drawings for erection using cranes

ABC ERECTION CONCEPTS

Select Cranes - Module Weight /

Pick Radius

Use Single Crane

Use Two Cranes

Bridges over Waterway

Bridges over Roadway

Bridges over Waterway

Bridges over Roadway

Erection Concepts for Bridge Replacement Using Cranes

Fact

ors

to

Co

nsi

der

Weight of Module

Pick Radius

Crane Set Up Locations

Ground Access / Barge / Causeway / Work Trestle

Truck Access for Delivery

Erection Concepts for Bridge Replacement Using Cranes

Short Single Span over Stream

Cranes selected for 90 Kip pick

Longer Span over Roadway

Weight up to 200 kips

Erection with ABC Construction Technologies

• Use ABC construction technologies where ground access for cranes below the bridge may be limited.

• ABC technologies that allow construction from above:

– Above Deck Driven Carriers

– Launched Temporary Bridge

– Transverse Gantry Frames

– Longitudinal Gantry Frames

Above Deck Driven Carriers

Allows fast rate of erection

Rides on existing bridge, new

bridge (check capacity to support)

Ideal for bridges with many spans.

long viaducts

Launched Temporary Bridge • Sites with limited ground access or long spans

• Launched across or lifted over a span to act as a “temporary bridge”

• Used to deliver the heavier modules without inducing large erection stresses.

• Temp bridge can also support transverse gantry frames

Gantry Frames

Longitudinal Gantry Frame

Transverse Gantry Frame

• The LRFD Design Specifications do not explicitly deal with the unique aspects of large scale prefabrication

• In some cases, the most extreme load case may occur during shipping and handling.

• The work in SHRP2 R04 entailed the identification of any shortcomings in the current LRFD Bridge Design Specifications

• Recommendations are provided for addressing these limitations.

ABC Design Specifications for LRFD

ABC Specific Construction Loads

• Dynamic Dead Load Allowance—An increase in the self-weight of components to account for inertial effects during handling and transportation

• Camber Leveling Force—A vertically applied force used to equalize differential camber prior to establishing connectivity between the elements.

RECOMMENDED PROVISIONS FOR LRFD DESIGN OF PREFABRICATED SYSTEMS FOR ABC

(NEW SECTION)

XX.1 General XX.2 Design Objectives XX.3 Loads and Load Factors XX.4 Analysis XX.5 Control of Cracking XX.6 Lifting and Handling Stresses XX.7 Prestressed Components XX.8 Design of the Grouted Splice Coupler XX.9 Provisions for Joints XX.10 Provisions for Steel Composite Systems

Economical ABC Design • In ABC design the careful determination of span arrangement,

girder spacings and module dimensions for shipping and erection can add significant savings.

• Consider ABC as an option during preliminary design

• Not all sites are suited for ABC -- Reference: FHWA Decision-Making Framework for ABC

ABC Design Examples

ABC Design Examples

• Three ABC design examples for prefabricated systems in the toolkit:

– Decked Steel Girder

– Decked Precast Prestressed Girder

– Precast Pier

• Design Criteria:

• AASHTO LRFD (5th Edition)

• Supplemental ABC criteria

The design examples provide step by step guidance on the overall

structural design of bridge components for ABC

LRFD for ABC Design

• The design of most ABC elements and systems follows traditional LRFD design specifications.

• Design the ABC elements and the completed structure using all applicable LRFD Limit States

• Additional requirements apply for ABC connections, lifting and moving of prefabricated elements and modules.

Decked Steel Girder Design for ABC

• Three Stages for Design

Prefabrication Stage (many support options)

– Load Case 1 = Dead load on module steel section only

– Load Case 2 = Dead load on module composite section

Erection Stage (many lift options)

– Load Case 3 = Modules are lifted into place

Final Stage

– Load Case 4 = Modules are assembled and made continuous » DL

» FWS

» LL + IM

» Utilities

Decked Steel Girder Design for ABC Erection Stage

• Erection Loads

– Analysis for pick points / supports shown on plans

– Contractor may select other erection method and do own erection analysis

• Erection Limit State

– Load Factor for erection dead Loads

– IM for dead loads

• Erection Stresses

– Flexural stresses < Allowable

Decked Prestressed Concrete Girder Design Camber Leveling Forces

• Control of differential camber at erection is key to

proper fit up

• If the prescribed tolerance cannot be attained use an approved leveling system to equalize cambers

• Camber leveling forces cause additional concrete tension – need to be factored into the girder design

• Reduce allowable tension

• ABC aspects Illustrated in design example

• Recommended Special Requirements for ABC

• Focus heavily on means and methods requirements for rapid construction.

New Section in LRFD Construction Specifications

XX.1 GENERAL

XX.2 RESPONSIBILITIES

XX.3 MATERIALS

XX.4 FABRICATION

XX.5 SUBMITTALS

XX.6 QUALITY ASSURANCE

XX.7 HANDLING, STORING, AND TRANSPORTATION

XX.8 GEOMETRY CONTROL

XX.9 CONNECTIONS

XX.10 ERECTION METHODS

XX.11 ERECTION PROCEDURES

ABC Construction Specifications

• Review the ABC Standard Plans and Design Examples

• General Information Sheets Introduce the intent and scope of the ABC standard plans and details -- includes instructions to designers so that all the key ABC issues are addressed

• Engineer of Record (EOR) should perform own ABC design calculations for the site using the examples as a guide

• EOR to customize the standard plans for the site --- span lengths / bridge width / module size / skew / foundations / etc

• Adapt ABC Special Requirements for construction

• EOR to add any aesthetic enhancements as needed or use lightweight concrete to reduce erection weights

Using the ABC Toolkit

ABC Design Example

Organization of Deck Bulb Tee Design Example General: Design Philosophy Design Criteria Girder Design: Permanent Loads Precast Lifting Weight Live Loads Prestress Losses -- Erection Prestress Losses -- Final

Concrete Stresses at Release Concrete Stresses at Erection Concrete Stresses at Final Flexural Strength Shear Strength Negative Moment Design Camber and Deflections at Release / Erection / Final

*** Engineer of Record should perform own ABC design

Closing

• New generation of ABC systems are economical to construct and designed for durability

• SHRP2 R04 ABC toolkit and training materials will be available to provide guidance to those new to ABC

• ABC costs are coming down with repeated use

• The time for ABC is now

Join us for the February 16 webinar on the Iowa and NY ABC projects