Devin K. Harris

NETWORK PAVEMENT EVALUATION WITH FALLING-WEIGHT DEFLECTOMETER AND GROUND-PENETRATING RADAR

Nondestructive testing has become an integral part of pavement evaluation and rehabilitation strategies in recent years. Pavement evaluation employing the falling-weight deflectometer (FWD) and ground-penetrating radar (GPR) can provide valuable information about pavement performance characteristics and be a very useful tool for project prioritization purposes and estimation of a construction budget at the network level. Traditional obstacles to the use of the FWD and GPR in pavement evaluation at the network level used to be expenses involved in data collection, limited resources, and lack of simplified analysis procedures. Indiana experience in pavement evaluation with the FWD and the GPR at the network level is presented. A network-level FWD and GPR testing program was implemented as a part of a study to overcome those traditional obstacles. Periodic generation of necessary data will be useful in determining how best to quantify structural capacity and estimate annual construction budgets. Three FWD tests per mile on 2,200 lane-mi of the network is recommended annually for network-level pavement evaluation. The information collected will allow the equivalent of 100% coverage of the whole network in 5 years. GPR data are recommended to be collected once every 5 years (if another thickness inventory is needed) after the successful network thickness inventory conducted in this study. GPR data collection is also recommended at the project level and for special projects. Both FWD and GPR data are recommended to be used as part of the pavement management system, together with automated collection of data such as international roughness index, pavement condition rating, rut depth, pavement quality index, and skid resistance.

Evaluation of Commercially Available Remote Sensors for Highway Bridge Condition Assessment

Improving transportation infrastructure inspection methods and the ability to assess conditions of bridges has become a priority in recent years as the transportation infrastructure continues to age. Current bridge inspection techniques consist largely of labor-intensive subjective measures for quantifying deterioration of various bridge elements. Some advanced nondestructive testing techniques, such as ground- penetrating radar, are being implemented; however, little attention has been given to remote sensing technologies. Remote sensing technologies can be used to assess and monitor the condition of bridge infrastructure and improve the efficiency of inspection, repair, and rehabilitation efforts. Most important, monitoring the condition of a bridge using remote sensors can eliminate the need for traffic disruption or total lane closure because remote sensors do not come in direct contact with the structure. The purpose of this paper is to evaluate 12 potential remote sensing technologies for assessing the bridge deck and superstructure condition. Each technology was rated for accuracy, commercial availability, cost of measurement, precollection preparation, complexity of analysis and interpretation, ease of data collection, stand-off distance, and traffic disruption. Results from this study demonstrate the capabilities of each technology and their ability to address bridge challenges.

Combined Imaging Technologies for Concrete Bridge Deck Condition Assessment

Evaluating the condition of concrete bridge decks is an increasingly important challenge for transportation agencies and bridge inspection teams. Closing the bridge to traffic, safety, and time consuming data collection are some of the major issues during a visual or in-depth bridge inspection. To date, several nondestructive testing technologies have shown promise in detecting subsurface deteriorations. However, the main challenge is to develop a data acquisition and analysis system to obtain and integrate both surface and subsurface bridge health indicators at higher speeds. Recent developments in imaging technologies for bridge decks and higher-end cameras allow for faster image collection while driving over the bridge deck. This paper will focus on deploying nondestructive imaging technologies such as the three-dimensional (3D) optical bridge evaluation system (3DOBS) and thermal infrared (IR) imagery on a bridge deck to yield both surface and subsurface indicators of condition, respectively. Spall and delamination maps were generated from the optical and thermal IR images. Integration of the maps into ArcGIS, a professional geographic information system (GIS), allowed for a streamlined analysis that included integrating and combining the results of the complimentary technologies. Finally, ground truth information was gathered through coring several locations on a bridge deck to validate the results obtained by nondestructive evaluation. This study confirms the feasibility of combining the bridge inspection results in ArcGIS and provides additional evidence to suggest that thermal infrared imagery provides similar results to chain dragging for bridge inspection.

Overload Flexural Distribution Behavior of Composite Steel Girder Bridges

AbstractUsing equations proposed by the AASHTO LRFD specifications, live-load distribution factors in bridge superstructures were calculated based on the linear-elastic behavior of the system. In this study, the applicability of these equations in predicting girder distribution behavior in the presence of high material nonlinearity and oversized loading scenarios was investigated. Two representative composite steel girder bridge superstructures, which are in service in the state of Michigan and had been previously subjected to a live-load testing program, were selected for this study. Sixteen cases were analyzed to study the effect of boundary conditions, loading position, and load configuration on the girder distribution behavior of the selected bridges as they approach their ultimate capacities. Comparing the results obtained from nonlinear finite-element analysis with those proposed by the AASHTO LRFD specifications demonstrated that the code-specified values for the distribution factors are overly con...

Bond Performance between Ultrahigh-Performance Concrete and Normal-Strength Concrete

AbstractUltrahigh-performance concrete (UHPC) exhibits several properties that make it appropriate for the rehabilitation of concrete structures. In this investigation, the application is focused on bridge deck overlays, but the study is equally applicable to other rehabilitation applications. Its negligible permeability makes this material suitable as a protective barrier that prevents any water or chemical penetration into the substrate. In addition, its ultra-high compressive strength and post-cracking tensile capacity could provide an improvement to the bearing capacity. However, for extensive acceptance, it has to be demonstrated that the bond between UHPC and normal strength concrete (NSC) offers a good long-term performance under a variety of operating conditions. The UHPC-NSC interface can experience high tensile, shear, and compressive stresses at both early and later life stages and the environmental conditions inherent to the operating environment. The success of the rehabilitation will depend ...

Characterization of Strength and Durability of Ultra-High-Performance Concrete Under Variable Curing Conditions

One of the latest advancements in concrete technology is ultra-high-performance concrete (UHPC), a fiber-reinforced, densely packed material that exhibits increased mechanical performance and superior durability compared with normal- and high-strength concretes. UHPC has great potential to be used in the bridge market in the United States. However, to gain acceptance by designers, contractors, precasters, and owners, this material needs to be tested according to ASTM International and AASHTO standards, and new practices must be developed. The variability in performance that is based on new challenges of mixing and curing must also be considered. The effects of curing regimes and specimen age on the strength and durability properties of a fiber-reinforced UHPC was investigated. Regardless of when the thermal treatment was applied, UHPC consistently attained compressive stresses above 30 ksi (207 MPa), a modulus of elasticity of approximately 8,000 ksi (55 GPa), and a Poissons ratio of 0.21. Flexural characteristics were enhanced with high-temperature curing. UHPC also demonstrated extremely high resistance to freeze–thaw cycling (with a durability factor of more than 100), coefficient of thermal expansion values only slightly higher than that of normal-strength concrete, and negligible chloride ion penetration. Furthermore, modified versions of ASTM and AASHTO standard testing methods were employed to aid in development of draft standards for testing some UHPC material properties in the United States that will eventually lead to a national design code.

Failure Characteristics and Ultimate Load-Carrying Capacity of Redundant Composite Steel Girder Bridges: Case Study

AbstractWith the existence of aging highway bridges within the U.S. transportation network, federal and local agencies typically encounter a wide assortment of maintenance issues ranging from cracking, spalls, delaminations, and corrosion to high load hits and fire damage. This paper presents an approach for capturing the full system-based behavior and stages of failure in the composite bridge superstructures as they approach ultimate capacity. This step is instrumental to understanding how redundant bridges behave in the presence of coupled and uncoupled damage and deteriorations. The investigation included a comprehensive nonlinear finite-element analysis of two representative intact composite steel girder bridges that were tested to failure and provided sufficient details for model validation. Results demonstrate the high degree of additional reserve capacity, inherent to redundant superstructures, over the theoretical nominal design capacity. A rational approach was established to describe the actual ...

Characterization of Interface Bond of Ultra-High-Performance Concrete Bridge Deck Overlays

Critical components of the nations bridge network, concrete bridge decks, are deteriorating at a rapid rate. This deterioration can be attributed to several factors; however, winter salt application, the diffusion of chlorides to the reinforcing steel, and eventual corrosion of the reinforcement are primary culprits. Multiple protection solutions, include concrete protective systems, sealers, additional cover to the reinforcement, membranes, and epoxy-coated reinforcement, but each solution has shortcomings and does not completely address the problem. Ultra-high-performance concrete, a relatively new material with exceptional strength and durability characteristics, may be a solution to these problems when it is used as a thin overlay on bridge decks. An experimental study was performed to evaluate the bond strength between an ultra-high-performance concrete overlay and a normal concrete substrate with different types of surface textures, including smooth, low roughness, and high roughness. Slant shear and splitting prism tests were performed to quantify the bond strength under compression combined with shear and under indirect tension. Test results demonstrated that under compressive loading, the bond strength was greater than the strength of the substrate when the surface texture was greater than the standard smooth finished mortar surface. For the bond strength under indirect tension, results were not highly sensitive to the surface roughness. In both cases, the measured bond strengths fell within the ranges specified in the American Concrete Institutes Guide for the Selection of Materials for the Repair of Concrete.

Effect of Deck Deterioration on Overall System Behavior, Resilience and Remaining Life of Composite Steel Girder Bridges

During the past few decades, several studies have been conducted to characterize the performance of in-service, girder-type bridge superstructures under operating conditions. Few of these efforts have focused on evaluating the actual response of the bridge systems, especially beyond the elastic limit of their behavior, and correlating the impact of damage to the overall system behavior. In practice, most of the in-service bridge superstructures behave elastically under the routine daily traffic. However, existing damage and deteriorating conditions would significantly influence different aspects of the structural performance, including reserve capacity, resilience and remaining service-life. The main purpose of this study is to evaluate the response of composite steel girder bridges under the effect of subsurface delamination in the reinforced concrete deck. Commercial finite element computer software, ANSYS, was implemented to perform a nonlinear analysis on a representative single-span, simply-supported bridge superstructure. The system failure characteristics were captured in the numerical models by incorporating different sources of material non-linearities, including cracking/crushing in the concrete and plasticity in steel components. Upon validation, non-linear behavior of the system, with both intact and degraded configurations, was used to evaluate the impact of integrated damage mechanism on the overall system performance. Reserve capacity of this bridge superstructure was also determined with respect to the nominal element-level design capacity. As vision to the future path, this framework can be implemented to evaluate the performance of other in-service bridges degraded under the effect of different damage scenarios, thus providing a mechanism to determine a measure of capacity, resilience and remaining service-life.

The Challenges Related to Interface Bond Characterization of Ultra-High-Performance Concrete With Implications for Bridge Rehabilitation Practices

Over the past decade there has been a significant increase in the number of concrete transportation structures reaching the end of their service lives, typically as a result of age and severe degradation. This deterioration is often the result of exposure to aggressive environments and substantial increases in vehicle loading. Rehabilitation is typically the most appropriate solution for these structures because of the high cost of full replacement, resulting in the need for cost-effective and suitable solutions for rehabilitation. Ultra-high-performance concrete (UHPC), one of the more recent advances in construction materials, appears to be a promising material for the repair of concrete structures. The potential benefit of UHPC is primarily derived from its negligible permeability, which prevents water or chemical penetration, and its high mechanical properties, which serve to increase the bearing capacity of the structure. Some of the primary challenges associated with the use of UHPC as a repair material are uncertainty in the bond performance and interaction with the existing substrate material. This paper focuses on the characterization of the interface bond and compatibility between UHPC and normal concrete. The testing program was conducted in the spirit of ASTM because no standard test methods currently exist for UHPC. In addition, a series of numerical models were developed to support the results obtained in the experimental investigations. The results highlight the exceptional performance of the bond, but they also demonstrate a number of challenges with respect to characterizing the bond. Specific challenges included characterization of surface roughness, premature specimen failure, material strength mismatch, and the quality and consistency of the testing methods used.