This paper presents the development of high-strength precast prestressed double-Tee girders for bridge construction. These girders use high-strength concrete (103 MPa), Grade 550 welded wire reinforcement, and 18-mm-diameter Grade 1860 prestressing strands at 51- by 51-mm spacing. The double-Tee section was used to simplify girder production and erection and to maximize span-to-depth ratio, which improves the construction economy and speed. To evaluate the efficiency of the developed girders, two full-scale 15.24-m long, 1.21-m wide, and 0.5-m deep single-Tee girders were fabricated by a precast producer and tested at the University of Nebraska structural laboratory. Transfer length measurements, development length testing, flexure capacity testing, and vertical and horizontal shear testing were conducted for each specimen. Test results have shown that the proposed high-strength bridge double-Tee girder can be designed using current LRFD bridge design specifications. Preliminary design charts for ...

The use of Ultra-High-Performance Concrete (UHPC) in beams has been growing rapidly in the past two decades due to its superior mechanical and durability properties compared to conventional concrete. One of the areas of interest to designers is the elimination of transverse reinforcement as it simplifies beam fabrication/construction and could result in smaller and lighter beams. UHPC has a relatively high post-cracking tensile strength due to the presence of steel fibers, which enhance its shear strength and eliminate the need for transverse reinforcement. In this paper, UHPC shear test data were collected from the literature to study the effect of the following parameters on the shear strength of UHPC beams without transverse reinforcement: compressive strength, tensile strength, level of prestressing, longitudinal reinforcement ratio, and fiber volume fraction. Statistical analysis of test data indicated that level of prestressing and tensile strength are the most significant parameters for prestressed UHPC beams, whereas longitudinal reinforcement ratio and tensile strength are the most significant parameters for non-prestressed UHPC beams. Additionally, shear strength of the tested UHPC beams was predicted using five models: RILEM TC 162-TDF, 2003, fib Model Code, 2010, French Standard NF P 18-710, 2016, PCI-UHPC Structures Design Guide, 2021, and Draft of AASHTO Guide Specification for Structural Design with UHPC, 2021. Comparing measured against predicted shear strength indicated that the French Standard model provides the closest prediction with the least scatter, where the average measured-to-predicted strength was 1.1 with a standard deviation of 0.38. The Draft of AASHTO provided the second closest prediction where the average measured-to-predicted strength was 1.3 with a standard deviation of 0.64. The other three models underestimated the shear strength.

This paper presents the analytical and experimental investigations performed to evaluate the structural behavior of Fiber-Reinforced Polymer (FRP) Honeycomb Sandwich Panels (HCSPs) used for bridge decks. The analytical investigation includes modeling FRP HCSPs using three Finite Element Models (FEM) and a simplified I-beam model. Comparing analysis results of the four models against experimental data from literature indicated that the simplified I-beam modeling method provides comparable accuracy while being computationally efficient. The experimental investigation includes flexure, creep, and fatigue testing of three full-scale HCSPs. Flexure testing was performed to estimate the linear stiffness and flexural capacity of the panel for calibrating the developed analytical models. Creep testing was performed by monitoring the panel behavior under sustained load for a six-month period using a wireless sensor system. Creep test results indicated that FRP HCSPs have insignificant creep deformations under service loads and room temperature. Fatigue testing performed for two-million cycles indicated that FRP HCSPs have adequate resistance to cyclic loads. On the other hand, static load testing of the fatigued panel showed a significant decrease in the panel stiffness.

Core extraction is the most common method for measuring concrete layer thickness in pavement construction. Although this method provides a very accurate thickness measurement, it is destructive, time-consuming, and does not provide adequate representation of the concrete layer thickness variability. Ground-penetrating radar (GPR) is a nondestructive evaluation technique that has been successfully used in several transportation applications, such as subsurface exploration and condition assessment. The main objective of this research is to investigate the accuracy and cost-effectiveness of using GPR in thickness measurement of concrete pavement for quality assurance purposes. A high-resolution 1.6-MHz ground-coupled antenna was used to perform grid scans and measure concrete thickness for several laboratory and field experiments. Results indicated that the use of metal objects underneath the concrete layer to improve bottom surface reflectivity was necessary for a reliable thickness measurement. Also, the u...