Performance of Bridge Materials by Structural Deficiency Analysis

The diagnostic concept of the structural deficiency of bridges is an essential engineering and management consideration with implications of performance. The structural deficiency analysis reflects the constructed system performance at the serviceability limit states. This paper analyzes trends in the structural deficiency of bridge inventory on the basis of material kind. A multiple-criteria diagnostic approach defines measures for condition, durability, and longevity performances and determines the overall equivalent performance. Thus, the structural performance levels reflect the structural reliability and vulnerability indices for bridge serviceability. The application of the approach analyzes the raw database of the entire bridge inventory in the United States. This comprehensive operational experience provides a national network-level comparative basis. The comparison suggests a relative need for improvements in one or more areas, such as design details or maintenance level, to increase the desirability of bridge construction materials. The results support more objective bridge management and decision making on distribution of funds, updating of policies, perfection of practices, and trade-off analyses for design, construction, maintenance, and replacement.     

Bootstrap Technique for Risk Analysis with Interval Numbers in Bridge Construction Projects

Bridges are principal and vital transportation structures. If risk management is not considered in bridge construction projects, objectives cannot be delivered on time, on budget, or with suitable quality results. Risk data set sizes and experts’ judgments are not usually sufficient for analyzing significant risks in bridge construction projects; moreover, the statistical distributions for risk parameter estimates are usually unknown. Standard parametric statistical techniques cannot provide appropriate solutions for cases with small data sets or unknown distributions. This paper proposes a new hybrid approach by using a nonparametric resampling technique and interval computations for risk analysis, in particular, for bridge construction projects. Bootstrap techniques produce more accurate inferences for comparing parametric techniques and are an alternative when the underlying parametric assumptions are not considered. Increasingly, because of the complexity and uncertainty in decision making at bridge projects, it is easier or more natural to provide interval values for parts or all of decision-making judgments. Furthermore, the goal of reducing standard deviations for both risk probability and risk impact compared with the conventional approach is another conclusion of this paper. The proposed approach is applied to a case in Iran to show the validity of the approach.     

Effect of Intermediate Diaphragms on Decked Bulb-Tee Bridge System for Accelerated Construction

One of the promising systems for accelerated bridge construction is the use of the decked precast prestressed concrete girders or decked bulb-tee girders for the bridge superstructure. Using the calibrated three-dimensional finite-element models through field tests, a parametric study was conducted to determine the effect of intermediate diaphragms on the deflections and flexural strains of girders at the midspan as well as the live load forces in the longitudinal joint. The following diaphragm details were considered: different diaphragm types (steel and concrete), different diaphragm numbers between two adjacent girders, and different cross-sectional areas for steel diaphragms. Five bridge models with different diaphragm details were developed, and the short span length effect on the bridge behavior was also studied. It was found that as long as one intermediate diaphragm was provided between two adjacent girders at midspan, changing the diaphragm details did not affect the girder deflection, the girder strain, and the live load forces in the longitudinal joint significantly. The effect of diaphragms on the midspan deflection was more prominent in the short span bridge; however, the reduction in the maximum bending moment by the diaphragms was more significant in the long span bridge than in the short span bridge. Specific design recommendation is provided in this paper.     

Engineering the Tower and Main Span Construction of Stonecutters Bridge

Stonecutters Bridge is the second longest cable-stayed bridge in the world and the first major bridge with a twin-box girder superstructure. It has a number of innovative structural features which made the construction of the bridge a significant challenge. This paper describes the fabrication and erection procedures for the bridge towers and the main span superstructure. These were developed in close interaction between the contractor and his construction engineering consultant to ensure a safe and effective construction. A stage-by-stage analysis was set up to model every step of the main span erection. The results were first used in the verification analyses to establish the adequacy of the permanent works throughout construction. In parallel, extensive wind tunnel testing as well as numerical analyses were performed to ascertain the effects of typhoon wind loads on the structure. The structural deformations predicted by the erection analysis were incorporated into a comprehensive geometric control procedure. This paper describes the construction methodologies developed and the related engineering input. It outlines studies undertaken to achieve an effective construction, ensure structural adequacy of all erection stages, ascertain an acceptable aerodynamic performance of the bridge, and exercise full control over the bridge geometry throughout erection.     

Tracking the Location of Materials on Construction Job Sites

Automated tracking of materials on construction projects has the potential to both improve project performance and enable effortless derivation of project performance indicators. This paper presents an approach by which materials tagged with radio frequency identification (RFID) tags can be automatically identified and tracked on construction sites, without adding to regular site operations. Essentially, this approach leverages automatic reading of tagged materials by field supervisors or materials handling equipment that are equipped with a RFID reader and a global positioning system receiver. To assess the technical feasibility of this approach, a mathematical model has been formulated such that the job site is represented as a grid and the location of materials within the grid is determined by combining proximity reads from a discrete range. Field experiments were conducted using an off-the-shelf RFID technology, and several metrics were developed to quantify the field performance and compare it with the theoretical positional accuracy derived from the discrete formulation.     

Effects of Mixed Corrosion, Freeze-Thaw Cycles, and Persistent Loads on Behavior of Reinforced Concrete Beams

The effects of mixed corrosion and freeze-thaw cycles on the mechanical properties of concrete prism specimens and the effects of mixed corrosion, freeze-thaw cycles, and persistent loads on the structural behavior of reinforced concrete beams were experimentally studied. A mixed solution of NaCl and Na2SO4 was used as a corrosive medium. Results show that under alternating actions of freeze-thaw and mixed corrosive agents, increasing the number of freeze-thaw cycles decreases the compressive strength and the elastic modulus of concrete and increases the compressive strain corresponding to the maximum compressive stress. The degradation of concrete material properties accelerates with the increase of water-cement ratio. For reinforced concrete beams, a 4% reduction in the loading capacity is found when these are subjected to freeze-thaw cycles and mixed corrosion only. However, if these actions are coupled with persistent loading, as expected during the service life of reinforced concrete structures in cold regions, a more rapid drop in the strength and deformation capacity of the beams is identified. The degradation is enhanced by a larger persistent-loading ratio. The significance of an accurate simulation of service conditions in the durability study of reinforced concrete structures in cold regions is highlighted.     

Characterization of Material Properties of HPS-485W (70 W) TMCP for Bridge Girder Applications

There are currently two methods of production for A 709 Grade HPS-485W (70 W)—quenching and tempering (Q&T) and thermomechanical controlled processing (TMCP). The TMCP enables plates to be rolled in longer lengths than is possible with Q&T; however, because of its recent introduction and a lack of material testing, relatively little is known concerning the effect of this new production method upon the intraplate variability of both tensile strength and toughness. Data from 96 tensile tests show that yield and ultimate strengths of HPS-485W (70 W) TMCP may be dependent upon plate thickness and orientation. The average yield strength was found to be lower than the 485 MPa (70 ksi) limit, while the average ultimate strength was within acceptable limits. Seventy-five Charpy V-Notch (CVN) specimens were tested, and all met the 48 J at ?23°C (35 ft-lb at ?10°F) AASHTO Zone III requirement for minimum toughness. Overall it was seen that HPS 485W (70 W) TMCP shows promise for bridge girder applications, but thicker plates do not currently meet all the ASTM A 709 standards, and should be reevaluated before being used in bridge construction on a large scale.     

Cost-Benefit Analysis of Embedded Sensor System for Construction Materials Tracking

Tracking and monitoring the location of materials on a construction job site is an important, yet commonly overlooked aspect of field data acquisition because timely information about the status of materials, equipment, tools, and labor resources are directly related to the successful completion of a project. With the advanced technologies and innovations in the construction industry, it has become technically viable to implement automated tracking for construction materials. Through the development of an embedded sensor system, this paper illustrates the implementation of pilot experiments examining the accuracy of a system’s performance. A cost-benefit analysis is conducted to illustrate labor savings associated with construction materials handling by comparison between manual and sensor-based materials tracking. The presented embedded sensor system can be extended into diverse application areas in tracking and monitoring framework by providing improved method of field data acquisition and information management.     

Improved Longitudinal Joint Details in Decked Bulb Tees for Accelerated Bridge Construction: Fatigue Evaluation

This companion paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck, which are cast and prestressed with the girder, provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, the use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is the perceived problem with durability of longitudinal joints used to connect adjacent girders. Four full-scale slabs connected by No. 16 (#5) headed reinforcement detail using a 152 mm (6 in.) lap length were fabricated and tested. An analytical parametric study was conducted to provide a database of maximum forces in the longitudinal joint. These maximum forces are then used to determine the loading demand necessary in the slab testing due to the service live load. Static and fatigue tests under four-point pure-flexural loading, as well as three-point flexural-shear loading, were conducted. Test results were evaluated based on flexural capacity, curvature behavior, cracking, deflection, and steel strain. Based on these test results, the improved longitudinal joint detail is a viable connection system that transfers the forces between the adjacent decked bulb tee girders.     

Interactive 3D CAD for Effective Derrick Crane Operation in a Cable-Stayed Bridge Construction

The high expectation of esthetic and functional quality in modern civil infrastructure has resulted in the increased demand for long span bridges. In advanced or developing countries, long span bridges such as cable-stayed and suspension bridges are considered even as landmarks that symbolize the prosperity or culture of the region. These long span bridges require higher level of design and construction technologies than other types of bridges. In particular, the construction of cable-stayed bridges involves precise and sophisticated operation of construction equipment such as derrick cranes. However, it is not easy to plan the operations of a derrick crane before the actual construction process takes place. Unexpected spatial constraints in the construction site may hinder the smooth operation of a derrick crane, which leads to lower than expected productivity and safety. This study applies interactive three-dimensional (3D) computer aided design (CAD) to the derrick crane operation for the purpose of identifying potential problems. Construction managers can have the two way process with the 3D CAD system to interactively test their construction plans and scenarios. The case study shows that the interactive 3D CAD system significantly improves the constructability of the cable-stayed bridge construction.     

Applicability of 4D CAD in Civil Engineering Construction: Case Study of a Cable-Stayed Bridge Project

Four-dimensional (4D) computer-aided design (CAD) has been credited with improving construction planning procedures. The integration of three-dimensional CAD with schedule information has enabled the effective detection of design and planning flaws in many construction projects. However, the benefit of 4D CAD has been centered on architectural constructions, as other areas such as civil infrastructure have seldom been the target of 4D CAD application. This paper presents a case study in which a cable-stayed bridge construction was analyzed and modeled using the 4D graphic simulation approach. The cable-stayed bridge was chosen for the case study because it suitably represents the complex nature of modern civil infrastructure. 4D CAD models were developed at three different levels of detail: activity, discrete operation, and continuous operation. The clear definitions of the three levels of detail of 4D CAD and their application results for the cable-stayed bridge are presented herein.     

Justifying Materials Selection for Reinforced Concrete Structures. I: Sensitivity Analysis

A substantial amount of research has been performed on the use of high performance construction materials and their effects on the anticipated frequency of maintenance and on the time to repair or replacement. Practical implementation of this work has been limited due to the lack of useable methods and information on the life-cycle costs and benefits of alternative approaches in the preliminary design stages of projects, when decisions regarding materials selection are typically made. The lack of simple methods for making quick life-cycle economic comparisons typically results in the use of conventional materials because their impact on performance is well known, even though high-performance materials may actually be more cost effective. This paper identifies the most significant parameters for evaluating the time to corrosion of reinforced concrete structures.     

Comparison of Prestress Losses for a Prestress Concrete Bridge Made with High-Performance Concrete

Five prestressed concrete girders made with high-performance concrete were instrumented using vibrating-wire strain gages. Their behavior was monitored for three years from the time of casting. The measured change in concrete strain at the centroid of the prestressing strands was used to evaluate changes in prestress. The total measured prestress loss was as large as 28% of the total jacking stress. Due to the higher stresses, this loss is larger than would be expected for a girder made with conventional-strength concrete. The observed values of prestress losses were compared with values calculated using the recommended AASHTO LRFD and NCHRP 18-07 procedures. The AASHTO LRFD method overpredicted the average prestress losses for the highly stressed Span 2 girders by 20% while the NCHRP method underpredicted the average losses by 16%. The NCHRP method was found to be more inclusive and adaptable to regional construction. The calculated NCHRP Span 2 losses were found to be within 10% of the average measured losses when the elastic shortening losses were calculated based on measured data and differential shrinkage was calculated based on continuous beams.     

Dynamic Three-Dimensional Visualization of Fluid Construction Materials

The presented work extends the state-of-the-art of visualizing discrete-event construction simulations in three dimensions (3D). Efficient methods are presented along with a tool, ParticleWorks, that can be used to animate simulated construction processes that involve unstructured, fluid construction materials as resources or byproducts. Common construction processes that involve such fluid materials include placing concrete, dumping dirt, shotcreting, sandblasting, dewatering, water distribution, and inserting slurry. The writers capitalize on a classical computer graphics concept called particle systems to design simple, simulation model-authorable, parametric-text methods that can describe arbitrary volumes of dynamic fluid construction materials in animated 3D virtual construction worlds. These methods can be used to instrument discrete-event simulation models (or other external authoring interfaces) to automatically generate dynamic visualizations of any modeled construction operations that commonly handle and process fluid construction materials.     

Full-Scale Experimental Investigation of Repair of Reinforced Concrete Interstate Bridge Using CFRP Materials

An experimental study is presented of the behavior of eight reinforced concrete bridge girders taken from a decommissioned Interstate bridge and retrofitted with three different carbon-fiber-reinforced polymer (CFRP) systems. Specimens were subjected to monotonic loading to failure with and without significant fatigue conditioning. Experimental observations indicated that intermediate crack-induced debonding was the dominant failure mode for monotonically loaded beams and that degradation of the CFRP-to-concrete interface was caused by fatigue conditioning. Conventional adhesive applied and near-surface mounted (NSM) CFRP systems behaved well under monotonic loads, with the NSM system exhibiting significantly greater ductility. Powder actuated fastener applied retrofit was observed to be less efficient, requiring a relative slip of the CFRP in order to engage the shear transfer mechanism of the fasteners. The application of current accepted design guidelines for FRP retrofit indicated that guidelines aimed at mitigating debonding failure appear to be appropriately conservative under monotonic loading conditions; however, a significant additional reduction in CFRP strain limits is required to account for even small levels of fatigue loading.     

Pipe Heating System with Underground Water Tank for Snow Thawing and Ice Prevention on Roads and Bridge Decks

In order to prevent traffic accidents on snow-covered bridge decks, the writers developed a new pipe heating system that uses only groundwater stored in a large underground tank. The underground tank provides geothermal energy, i.e., groundwater of constant temperature, through heating pipes embedded in concrete pavements with no electric heater or fuel boiler. The pipe heating system was constructed at approximately 50% of the cost of comparable systems. In addition, there is a reduction of 10% in operating costs compared with the previous system. The present paper outlines its design and construction and provides fundamental data for the developed system. The piped heating system has kept the road conditions safe during the winter season by always removing the snow and ice from the heated road and bridge sections earlier than the surrounding roads. According to long-term temperature measurements, this system has prevented the road temperature from decreasing below 0°C, even through nighttime and morning periods. This report presents the system as an economical and effective solution for snow thawing and ice prevention.     

Feasibility of Thermoplastic Composite Jackets for Bridge Impact Protection

The research focused on the effects of low velocity impact loading on high-strength concrete confined by a prefabricated polypropylene jacket and comparing the results with similar specimens confined by carbon fiber-reinforced polymer (CFRP) composites. In order to accomplish this, both static and dynamic load tests were performed. Concrete cylinders were used for static loading. Twelve concrete cylinders were prepared for static load testing: three were plain concrete and used as control specimens, three were wrapped with one layer of unidirectional CFRP composites, and six were confined by the polypropylene jacket. The thickness of the polypropylene wrap was machined to different thicknesses; three 3?mm and three 6?mm. The cylinders were standard (D×H) 152?mm×305?mm. Cylinders were loaded to failure in uniaxial compression using a Tinius-Olsen Universal Testing Machine. Impact testing was performed using four (D×H) 152?mm×914?mm columns. The columns consisted of one control sample; one CFRP composites wrapped, and two (one of each thickness) wrapped with polypropylene. Impact testing was conducted using an Instron drop-tower testing machine.     

Parametric Study of Posttensioned Inverted-T Bridge System for Improved Durability and Increased Span-to-Depth Ratio

Rehabilitation of the existing bridges is one of the most pressing needs in maintenance of the transportation infrastructure. As an example, more than 2,000 bridges in Kansas alone need to be replaced during the next decade. The majority of these bridges have spans of 30 m (100 ft) or less, and shallow profiles. The inverted-T (IT) bridge system has gained increasing popularity in recent years due to its lower weight and relatively larger span-to-depth ratio compared to the prestressed I-girder bridges. However, there are some limitations in replacing the existing cast in place (CIP) bridges with IT system. Implementation of posttensioning, which is the focus of this paper, is a promising solution for these limitations. This leads to a higher span-to-depth ratio and reduces potential transverse cracks in the CIP deck which is a major concern for corrosion of the reinforcement. An analytical research was conducted to identify the major parameters influencing the performance of a posttensioned IT bridge system. This was followed by a parametric study to explore the scope of these parameters and specify the design limits in terms of posttensioning stages, timing scenarios, and posttensioning forces. Concrete strength and different methods for estimating time-dependent restraining moments were addressed in this parametric study.     

Fiber-Sizing-Based Enhancement of Materials Durability for Seismic Retrofit

E-glass/epoxy-based jackets have been demonstrated to be an effective means of providing lateral confinement for the seismic retrofit and strengthening of concrete columns. When fabricated using appropriate procedures and covered with a protective coating these materials show good environmental durability. However, E-glass fibers are susceptible to attack and degradation by moisture and alkalis, causing concern for their use in humid and very moist climates or in applications where the jacketed columns are immersed in water. This paper describes the enhancement of durability through change in the sizing used on the fibers. Results of ring burst tests on three differently sized systems after immersion in a severe environment [water at 60°C (140°F)] are detailed, and it is shown that the use of the appropriate sizing can significantly reduce moisture-related degradation.