Annual Concrete Conference 2023 Program

Chris Hoberg (MnDOT), Angela Kingsley (HNTB), Arne Johnson (WJE)

Moderators: Maria Masten and Josh Edwards

After nearly three years of construction, the 3rd Avenue Bridge Rehabilitation is scheduled to be completed in the Fall of 2023. The historic bridge, which originally opened in 1918, was exhibiting significant concrete deterioration caused by several factors, including structural and thermal effects, chloride exposure, and freeze-thaw deterioration. After comprehensive inspection, testing, and alternatives studies, the decision was made to rehabilitate the bridge by removing the superstructure all the way to the arches and repairing significant portions of the structure that remained. The solutions developed and work extents were informed by the goal of extending the bridge service life a minimum of 50 years. Construction access, anchorage design, and project duration were key challenges uniquely managed using the CMGC contracting method. This presentation will highlight the history of the bridge, rehabilitation needs, superstructure design changes, repair design, construction inspection and testing performed before construction and during repair, and lessons learned during construction.

Cary Kopszynski, CKC Inc.

Moderators: Josh Edwards and Maria Masten

Productivity in the construction industry has not advanced significantly since the 1950’s according to a recent study by the McKinsey Global Institute. A major cause is insufficient collaboration between designers and contractors, which leads to diminished constructability of design and productivity of construction. Mr. Kopczynski will discuss several exciting new American Concrete Institute (ACI) initiatives directed at improving industrywide collaboration, including the recent rollout of PRO: an ACI Center of Excellence for Advancing Productivity.

Carol K. Shield, PhD, FACI; Professor Emeritus, University of Minnesota, Department of Civil, Environmental, and Geo- Engineering

Moderators: Mike Hemstad and Justin Lashley

ACI recently published 440.11-22 Building Code Requirements for Structural Concrete Reinforced with Glass Fiber-Reinforced Polymer (GFRP) Bars. This code is most appropriate for concrete structures that would be vulnerable to corrosion of the steel reinforcement. Likewise, structures that require non-ferrous reinforcement due to electro-magnetic considerations are also good candidates for GFRP reinforcement. Lack of a design standard has limited the use of GFRP in these types of structures. The purpose of this presentation is to introduce the new GFRP Bar Code. The presentation will discuss an introduction to GFRP rebar materials, an overview of what is covered in the Code, the full suite of standards needed by the designer and contractor, the major difference between reinforcing concrete with GFRP and steel, and some field applications of GFRP reinforced concrete structures.

Rafic G. Helou, PhD; Structural Concrete Research Engineer, Federal Highway Administration

Moderators: Justin Lashley and Mike Hemstad

The mechanical and durability properties of UHPC make it a compelling material for use in developing new solutions to pressing concerns about deterioration, repair, and speedy replacement of the nation’s aging highway infrastructure. Since its introduction into the US market in 2000, a series of research projects and infrastructure deployments have demonstrated the material’s capabilities to accelerate construction activities and deploy innovative solutions whose performance addresses the shortcomings of past practice. These efforts, coupled with a rise in interest in UHPC-based solutions by infrastructure owners, have culminated in the development and publication of an AASHTO LRFD Guide Specification for Structural Design with UHPC unlocking new avenues of structural efficiency, durability, and safety. This presentation will highlight compelling solutions offered by UHPC and discuss the key aspects of its material behavior and structural design guidance.

Dave Zwicke, Portland Cement Association

Moderators: David Meyer and Alf Gardiner

Economist Dave Zwicke returns to deliver an intriguing and entertaining presentation on the economic trends affecting Minnesota and the national economy. This year was historic in countless ways. What’s in store for 2024? Zwicke will present his analysis regarding the US economy and how it translates into construction activity and cement consumption for 2024.

Ben Worsfold, PhD; Assistant Professor, University of Minnesota, Department of Civil, Environmental, and Geo- Engineering

Moderators: Catherine French and Tony Foggia

Connections between reinforced concrete structural members often rely on the yielding of reinforcing bars to resist forces and dissipate energy. Development length provisions are commonly used to ensure bar yielding. Recent physical tests have demonstrated that groups of reinforcing bars developed into a receiving member can fail prematurely in a concrete breakout mode before bar yielding. This failure mode is not routinely checked in design even though it can potentially cause premature failure of connections from beams to columns, columns to foundations, coupling beams to walls, and other connections where groups of bars are relied upon to transfer forces. Recent physical tests and finite element simulations have suggested that distributed shear reinforcement throughout the concrete breakout cone region can increase the connection strength and displacement capacity. The ACI 318-19 building code currently does not allow engineers to add the strength contribution of reinforcement to the concrete breakout strength. A novel design methodology is proposed to calculate the shear- reinforced breakout strength. Detailing recommendations are discussed.

Peter Taylor, PhD, PE (IL), FACI; Director, National Concrete Pavement Technology Center, Iowa State University

Moderators: Alf Gardiner and Mary Vancura

With sustainability at the forefront of our worldwide discussion, practitioners need to understand that concrete and materials are forever going to be evolving and what our grandparents once knew as concrete will constantly be changing.  This presentation will focus on the anticipated changes to materials, mixture designs, construction practices and acceptance specifications that will be needed now and into the future.

Mike Beer, Lead AP, Gardner Builders and Matt Thomas, PE, SE, MBJ

Moderators: Mike Martin and Mike Murphy

The Dayton’s Project included renovation of 1.2-million square feet of the historic downtown building originally built in 1903. This significant reposition project included structural improvements to 14 historic additions and uncovered a century of various types of construction. The presentation will provide an overview of the renovation project, a review of historic concrete construction and its limitations, and strategies that were employed to provide structural capacity for new program functions and configurations.