The purpose of this session is to offer authors/speakers an open forum for presentation of recent technical information that does not fit into other sessions scheduled for this convention. Any aspect of structural analysis or design, concrete materials science, or construction, manufacturing, use, and maintenance and health monitoring of concrete structures and products can be presented.
Learning Objectives:
(1) Discuss the Effect of temperature and voids on the electrical behavior of self-sensing concrete;
(2) Examine the Concrete Pore Structure using Combined Nitrogen Sorption, SEM, and Micro-CT with Image Analysis;
(3) Examine the Influence of Fiber Orientation and Section Geometry on the Shear Strength of UHPC Members;
(4) Report on High-Resolution Crack Monitoring in Concrete Structures Using Visual Fiducial Tags;
(5) Examine the Advancing Sustainability in UHPC;
(6) Assess Anchorage strength of textured epoxy-coated hooked bars.
This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.
Effect of Temperature and Voids on the Electrical Behavior of Self-Sensing Concrete
Presented By: Yen-Fang Su
Affiliation: Louisiana State University
Description: Structural Health Monitoring (SHM) has become a crucial aspect of maintaining and ensuring the integrity of concrete infrastructure. One promising innovation for SHM is the use of advanced materials such as self-sensing cementitious composites (SSCCs). These composites incorporate functional fillers such as carbon black (CB), carbon fibers (CF), graphite powder (GP), and carbon nanomaterials into conventional concrete, enhancing both mechanical and electrical properties. SSCC has the ability to exhibit measurable changes in electrical resistance in response to the applied mechanical stress or strain, which enables the real-time sensing of structural deformation.
Multiphysics modeling of self-sensing concrete enables accurate simulation of how mechanical, electrical, and environmental factors interact within the material. This helps optimize its design for real-time structural health monitoring while reducing the need for costly physical testing. Multiphysics modeling can simulate SSCC’s coupled mechanical and electrical behavior. In this study, Multiphysics modeling was conducted using COMSOL software. The SSCC specimens modeled were 2×2×2 in³ (Figure 1). The models were validated using experimental data. Then, the temperature of the sample was varied (40°F, 60°F, 80°F, and 100°F), and the electrical response of the specimens was studied using the resistance and fractional change in resistance (FCR), as shown in Figure 1. Furthermore, electrical response was studied for various void patterns of void sizes 0.01 mm, 0.1 mm, 1 mm, and 10 mm. The findings provide valuable insights into the behavior of SSCCs under real-world conditions, laying the groundwork for smarter, more resilient infrastructure through data-driven design and continuous structural awareness.
Influence of Fiber Orientation and Section Geometry on the Shear Strength of UHPC Members
Presented By: Amjad Diab
Affiliation: Pivot Engineers
Description: Accurate assessment of the shear strength of ultra-high-performance concrete (UHPC) members is essential to fully leverage the potential of this advanced material in designing the next-generation infrastructure. This study examines the influence of fiber orientation and cross-sectional geometry in improving the evaluation of UHPC beams shear strength.
The authors developed a hybrid shear strength model that integrates theoretical formulations based on the Modified Compression Field Theory with parameters derived empirically, as well as analytically. The model also includes a novel expression for the angle of diagonal compressive stresses, developed based on compatibility conditions and experimental observations.
The model was validated against a comprehensive database of 534 shear-critical UHPC beam tests compiled from 51 different published studies. The model demonstrated strong predictive performance across a wide range of member configurations, achieving a coefficient of determination (R²) of 0.95, an average experimental-to-predicted strength ratio of 1.05, and a coefficient of variation of 0.27. This presentation introduces the shear strength model, the influence of fiber properties, and the model’s performance compared to experimental UHPC beam tests.
High-Resolution Crack Monitoring in Concrete Structures Using Visual Fiducial Tags
Presented By: Yuan Tian
Affiliation: Thornton Tomasetti
Description: The integration of advanced computer vision technologies into structural monitoring is transforming civil engineering practice. Visual Fiducial Tags provide a low-cost, robust, and scalable means of accurately tracking the concrete damage over time under diverse environmental conditions. This study presents a practical implementation of Visual Fiducial Tag-assisted monitoring in a semi-enclosed parking garage. Fiducial tags that were installed across concrete slabs enabled precise, repeatable measurements of in-plane cracking. High-resolution image data captured using a Matterport scanner and cameras are processed through the photogrammetry workflow. Crack geometries are accurately extracted and scaled through image rectification and enhancement, allowing detailed mapping of crack locations directly onto engineering drawings. The method significantly improves inspection efficiency, ensures traceable documentation, and establishes a comprehensive baseline dataset for long-term structural health monitoring. Validation against conventional crack gauges confirms the accuracy and reliability of the approach, demonstrating that Visual Fiducial Tag-assisted monitoring meets engineering precision requirements while reducing labor and cost.
Advancing Sustainability in UHPC: Enhancing SCM Dispersion Techniques for Improved Performance
Presented By: Aagya Dahal
Affiliation: University of Connecticut
Description: Ultra-High-Performance Concrete (UHPC) offers exceptional properties but contributes to carbon emissions due to high cement content. To reduce cement usage and improve sustainability, Supplementary Cementitious Materials (SCMs) like silica fume, glass powder, limestone powder, and fly ash are used. However, SCM agglomeration can limit UHPC performance. This study investigates SCM dispersion and strategies for better integration into UHPC. Cement pore solutions were extracted using vacuum filtration and pressure squeezing to analyze ionic composition under varying cement types, w/b ratio, and pressures, with results indicating that these factors significantly affect ionic composition. SCM dispersion was then evaluated in deionized water, untreated pore solution, and PCE-treated solutions. Sedimentation and optical microscopy confirmed that PCE and ultrasonic treatment improve dispersion. Ongoing particle size analysis will provide further insights. Figure 1 shows the summary of the methodology used in this study.
Anchorage Strength of Textured Epoxy-Coated Hooked Bars
Presented By: SANJEEB THAPA
Affiliation: University of Kansas
Description: The ACI Building Code and AASHTO Bridge Specifications require the development lengths of epoxy-coated hooked bars to be 20 percent longer than for uncoated bars. A new textured epoxy coating produced by Sherwin-Williams provides corrosion protection along with improved bond strength and damage tolerance. Tests have demonstrated that the bond strength of straight textured epoxy-coated reinforcement (TECR) satisfying ASTM A1124 is equivalent to the bond strength of uncoated bars. Tests are now underway to compare the anchorage strengths of textured epoxy-coated and uncoated hooked bars that may permit the use of a coating factor of 1.0 for both within the ACI Building Code and the AASHTO Bridge Specifications. This study examines the bond strength of TECR using beam-end specimens, as required by ASTM A1124, and the anchorage strength of hooked TECR using simulated beam-column joint specimens. Twelve beam-end specimens – six pairs of TECR and uncoated bar specimens – were tested in accordance with ASTM A944 and A1124, and thirteen pairs of simulated beam-column joint specimens containing TECR and uncoated No. 5, No. 8, and No. 11 bars were tested. Figure 1 shows the test setup for the simulated beam-column joint specimens. The TECR exhibited a bond strength equal to 100.3% of that of uncoated reinforcement from the same heat of steel in the beam-end test. Similarly, the TECR exhibited an anchorage strength equal to 106%, 104%, and 95% of that of uncoated No. 5, No. 8, and No. 11 reinforcement in the simulated beam-column specimen test.