Sessions & Events

 

Please note: All sessions and events take place in Central Daylight Time: CDT (UTC-5).

H=Hyatt Regency Dallas; U=Union Station

Concrete Olympics: Design, Construction, Evaluation, and Repair of Concrete Bridges and Structures with Members of the ACI, KCI, TCI, and FIB, Part 1 of 4

Monday, October 24, 2022  1:30 PM - 3:30 PM, H-Reunion E

Korea Concrete Institute
Taiwan Concrete Institute
International Federation for Structural Concrete
The special sessions present recent advances in the design, construction, evaluation, and repair of concrete structures and materials with an emphasis on international perspectives with members from four major concrete institutes around the globe: the American Concrete Institute (ACI), Korea Concrete Institute (KCI), Taiwan Concrete Institute (TCI), and International Federation for Structural Concrete (FIB). Presentations encompass a variety of technical aspects such as the refined analysis and assessment techniques of concrete members, damage detection and mitigation, seismic behavior, durability performance, and repair/strengthening of constructed structures. Both experimental and analytical investigations are of interest. The sessions bring to light state-of-the-art knowledge and provide an opportunity to discuss current challenges and technical demands. Critical information will be provided to those who lead tomorrow’s structural design, construction, evaluation, and repair, including practicing engineers, government officials, and academics.
Learning Objectives:
(1) Discuss the performance of concrete structures under aggressing loadings;
(2) Report the recent advances in research concerning concrete materials and structures;
(3) Recognize a new direction for the design of concrete members;
(4) Relate how research outcomes are translated into practice.

This session has been AIA/ICC approved for 2 CEU/PDH credits.


Advanced NDE Methods for Condition Assessment and Imaging of Bridge Conditions

Presented By: Larry Olson
Affiliation: Olson Engineering, Inc.
Description: There are a number of non-destructive evaluation (NDE) methods applicable to condition assessment investigations of bridge superstructure and substructure that are now being used on highway bridge projects. One of the most common problems in bridges is the corrosion of steel-reinforced concrete decks which causes delamination and spalling of the concrete due to de-icing salts or sea salts. Impact Echo Scanning, Surface Waves Scanning and Ground Penetrating Radar are all used to map out damage areas (the first 2 methods) and indicate the potential for damage and concrete cover depth over top steel reinforcement in the case of Radar. The use of impact echo and surface waves scanning allows for mapping out top and bottom steel delaminations due to rebar corrosion for asphalt overlaid concrete decks. Impact Echo Scanning is also useful for detecting ungrouted ducts of post-tensioned bridges to mitigate the risk of future corrosion. Fusion of NDE data and photogrammetric images will be illustrated for results of Impact Echo Scanning and Ground Penetrating Radar Scanning plus Spectral Analyses of Surface Waves tests of post-tensioned concrete bridge girders. The NDE results were overlaid on photogrammetric images of visible corrosion/cracking damage to the concrete bridge girders of an aging bridge due to de-icing salts and a marine environment. Ultrasonic pulse velocity and velocity tomography analyses can clearly image internal void/honeycomb in concrete elements of bridges for repairs.


Structural Safety of Concrete Bridge Decks with Varying Rebar Covers

Presented By: Nur Yazdani
Affiliation: University of Texas at Arlington
Description: Corrosion of reinforcing steel is one of the leading causes of deterioration in concrete bridge decks, thereby reducing service life and increasing life cycle cost. The concrete cover above the rebars is an important parameter that can affect the deck durability and structural safety. State highway departments typically provide minimum rebar covers as one of the key corrosion protection measures. However, prevalent construction procedures often result in variations in the concrete bridge deck rebar covers from the recommended values. This study evaluated the extent of bridge deck reinforcement cover variations in two existing bridges in the Dallas-Fort Worth metroplex and determined the related impact on deck negative moment capacity over the girder supports of decks. The bridges were initially constructed in 1958 and 1959 and replaced in 2017 and 2018, respectively. The current study was conducted on the replaced bridges that was constructed using precast I-girders with composite precast concrete deck panels and cast-in-place topping. We used Ground Penetrating Radar (GPR) scans over the deck surface with ground coupled high-frequency antennae. It was found that the top cover exceeded the as-built plan specified cover of 64 mm by 13 mm in 14% to 45% of the deck area, whereas the exceedance was 25 mm in 3% to 42% of the deck area. This resulted in reduction of the flexural capacity of the deck by 9% and 18%, respectively. However, the decks for both bridges were found to be safe to carry the factored applied negative bending moments.


Recent Research and Applications of Iron-Based Shape Memory Alloys for Concrete Structures in Europe

Presented By: Antoni Cladera
Affiliation: University of the Balearic Islands - ESQ0718001A
Description: Recent research works have shown the feasibility of using iron-based shape memory alloys (Fe-SMAs) in structural rehabilitation projects, especially for flexural and shear strengthening. At the same time, real applications of Fe-SMAs are becoming more common in Europe, as they can be found in the construction market as strips and corrugated bars. In this presentation, the key properties of this relatively low cost shape-memory alloy will be presented, paying particular attention to how to use them for prestressing thanks to the shape memory effect.


Nonlinear Numerical Model for Performance-Based Seismic Design of RC Building Structures

Presented By: Honggun Park
Affiliation: Seoul National University
Description: In Korea, performance-based seismic design is being used for seismic design of high-rise buildings. In the year of 2021, Korea Concrete Institute published a new guideline for nonlinear numerical analysis modeling of RC moment frames and wall structures. In this presentation, the major parts of the guideline are presented: definitions of performance of members (deformation-controlled behavior and force-controlled behavior), model classification and methods (fiber model and plastic hinge model), requirements of test verification, plastic hinge models of beams, columns, beam-column joints, walls, coupling beams, and cyclic behavior model. Several modeling examples were also included for better understanding of readers. Particularly, the plastic hinge models were developed based on current strength degradation models published in international journals including the ACI structural journal. This guideline can be used for seismic evaluation of existing RC structures as well as design of new RC structures.


Performance-Based Electrochemical Analysis of an Innovative Magnesium Phosphate Cement Coating to Mitigate Mild Steel Bar Corrosion

Presented By: John Myers
Affiliation: Missouri S&T
Description: Corrosion of steel is the largest threat to concrete structures. In the United States, the total direct cost of corrosion is estimated at $276 billion per year, which is 3.1% U.S. gross domestic product (GDP). Preventing steel corrosion is critical to ensure long service-life in a RC structure. This study engages in the investigation of the anti-corrosion performance of rebar in magnesium phosphate cement (MKPC) coating and ordinary Portland cement (OPC) coating detailed the electrochemical properties from the open-circuit potential (OCP), polarization resistance (PR) and electrochemical impedance spectrometer (EIS), and morphology from scanning electron microscope (SEM). The results show that the MPC coating layer offered far better corrosion protection than OPC coating and hold great promise for a new innovative coating technology to mitigate mild steel corrosion in an economical sustainable fashion.


Seismic Performance and Nonlinear Strain Analysis of Mechanical or Grouted Splices for High-Strength Reinforcement in Concrete Structures

Presented By: Hung-Jen Lee
Affiliation: National Yunlin University of Science & Technology
Description: Engineers are interested to use Grade 80 and 100 bars in place of Grade 60 bars as longitudinal reinforcement for cost savings and easy construction. The primary drawback may be the longer splice lengths required for higher yield strength bars. The use of ductile and strong mechanical splices provides viable solutions. Today, several mechanical couplers and coupling sleeves are developed for connections of prefabricated steel cages or precast concrete structures to accelerate bridge or building construction. The seismic performance of precast concrete columns connected with mechanical or grouted splice sleeves is of interest and investigated in this study. Cyclic tests and nonlinear strain analysis of mechanical or grouted splices are conducted to validate the use of high-strength reinforcement in seismic concrete structures. Finally, the strain demands of mechanical splices in concrete structures are determined by moment, curvature, and drift analysis. Loading protocol and acceptance criteria of mechanical or grouted splices are proposed for concrete structures in high seismic zones.

Upper Level Sponsors

Ash Grove
Baker
Conseal
Controls Group
Euclid Chemical
GCP
Master Builders
PoreShield
PS=0
ACI Northeast Texas Chapter

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