Accelerated Bridge Construction Techniques Research Articles

Repairable Precast Concrete Bridge Columns for Seismic Events

In multispan bridges excited by ground shaking, columns are usually the target ductile members. Although current practice is successful in attaining the no-collapse objective for bridges, columns are usually damaged at displacements associated with this performance level. Minor damage can be repaired, but excessive damage is usually beyond repair. A new design paradigm with minimal damage and repair need is gaining interest. The benefits of such a design can be increased if low-damage technologies are combined with accelerated bridge construction techniques. The main goal of the present study was to develop rein¬forced concrete bridge columns that are fully precast concrete, low damage, and repairable through compo¬nent replacement. To achieve the project objectives, 20 repairable precast concrete alternatives were developed and ranked. Subsequently, the top three candidates were designed at 50% scale, constructed at a precast concrete plant, and tested in a laboratory. The precast concrete columns incorporated different exposed fuses, such as stainless steel bars and steel tendons, advanced materials such as ultra-high-performance concrete, a self-centering mechanism, or an accelerated bridge construction socket connection. A reference cast-in-place concrete column was included for comparison. Each precast concrete column was tested twice. It was found that the repair of the precast ultra-high-perfor¬mance concrete columns with exposed tendons was easy,

Cyclic Bond-Slip Behavior of Partially Debonded Tendons for Sustainable Design of Non-Emulative Precast Segmental Bridge Columns

The precast segmental bridge columns incorporating resettable sliding joints have been proposed to extend the accelerated bridge construction techniques to regions of moderate to high seismicity while fulfilling the sustainability-based resilient seismic design concept. Following a rethink of the design strategy in the light of inspirations from hybrid sliding-rocking joints, the design of resettable sliding joints can accommodate a certain amount of horizontal sliding displacement and adopt partially debonded tendons in a vertical manner, probably resulting in complicated tensile-flexural loading scenarios in these tendons during earthquakes, which is rarely considered in practice. In this paper, the sustainable design of resettable sliding joints is introduced. A tailor-made setup was established and simplified cyclic bond-slip tests were conducted to validate the practicality of the proposed partially debonded tendon system. Twelve specimens were fabricated using different strands and grouting techniques, and a two-stage numerical model was proposed to interpret the experimental results of seven typical specimens. The results suggest that the deterioration of reloading stiffnesses can be captured by an additional effective length caused by bond failure, and the strands perform mostly elastically under relatively large transverse displacements. The loading stiffness of the anchorage is 26.3 kN/mm, and it has significant effects and the proposed two-stage model can satisfactorily capture the envelope of the response of the partially debonded tendons, providing practical design for the proposed partially debonded tendons used in sustainable non-emulative precast segmental bridge columns.

Development of High Early-Strength Concrete for Accelerated Bridge Construction Closure Pour Connections

Abstract: Accelerated bridge construction (ABC) has become a popular alternative to using traditional construction techniques in new bridge construction and existing bridge deck replacement because of the reduction of time spent in field activities. A key feature of bridges built using ABC techniques is the extensive use of prefabricated components. Prefabricated components are joined in the field using small volume closure pours involving high performance materials (steel and concrete) to ensure adequate transfer of forces between components. To date, the materials developed for closure pours have been based on proprietary components, so a need has arisen for development of mixes that use generic components. The goal of this research was to create a method to develop concrete mixtures that are designed using generic constituents and that satisfy performance requirements of accelerated bridge construction closure pours in New England, primarily high early strength and long-term durability. Two concrete mixtures were developed with a primary goal of reaching high-early strength while maintaining constructability. The secondary goal of the concrete mixtures was to be durable; therefore, measures were taken during the development of the concrete mixture to generate a mixture that also had durable properties.

Back in Action

At one of Northern Virginia’s most complex and notoriously congested intersections, the superstructure of a critical highway overpass was demolished, removed, and replaced in a single weekend. The design’s accelerated bridge construction techniques included three composite units that were prefabricated off-site and a customized very early strength latex concrete mix for the deck closure that provided the cure time, strength, and durability necessary to get the job done on time.

Service Life Design of Deck Closure Joints in ABC Bridges: Guidelines and Practical Implementation

Closure joints are commonly used in bridge deck to connect two adjacent prefabricated elements in accelerated bridge construction. The current practice of closure joints utilizes the use of different materials such as normal strength concrete and ultra-high performance concrete with the use of different reinforcement details such as straight bars, hooked bars, and headed bars. The design of closure joint to meet strength limit state is quite simple, however, the design for service life for these joints is quite challenging. Framework for service life design of closure joints in bridges, built using accelerated bridge construction techniques, is developed in this paper. This framework includes several steps: 1) identification of project requirements especially those influences the service life of closure joints; 2) identification and selection of feasible closure joint types suitable for the project requirements; 3) identification of factors which influence the service life of closure joints along with mode of failures and consequences; 4) identification of suitable approaches or strategies for mitigating failure modes or assessing the risk of damage; 5) modification of closure joint detail using mitigation strategies which may result in the development of several alternatives and options for each closure joint type; 6) estimation and comparison of service life for each modified alternative using finite or target service life approach; and 7) conducting life-cycle cost analysis for each modified alternative along with the selection of the optimum closure joint details to meet both strength and service life demand. This framework is used in practical design implementation example for 1400-ft long bridge in Boston, Massachusetts, US. Several closure joints details were studied under this research such as the use of normal strength concrete with straight bars, 180-degree hooked bars, 90-degree hooked bars, and headed bars along with the use of ultra-high performance concrete with straight bars. This paper summarizes the outcome of the design for service life of those closure joints comparatively.

Accelerated bridge construction projects using high performance concrete

The National Bridge Inventory (NBI) of the United States includes more than 600,000 highway bridges. Approximately 25 % of the nation’s inventory is structurally deficient or functionally obsolete. Currently, the Federal Highway Administration (FHWA) is investigating different alternatives to build new bridge with longer life-span, lower maintenance, and repair needs.Currently, the FHWA is successfully using accelerated bridge construction (ABC) techniques to expedite the construction of new bridges, and minimize material, labor, and equipment cost. In this research, the ABC of new bridges using prefabricated bridge elements and systems (PBES) is discussed, including the fabrication of precast/prestressed elements using an economic high performance concrete (HPC) mix, developed using local construction materials. The successful use of HPC in fabricating PBES used in ABC techniques allows the FHWA to construct new bridges under current budget restraints. This improves the overall rating of the bridge network within the United States.

LBJ express project: an example of accelerated bridge construction techniques for large and complex projects

ABSTRACTThe I-635 Managed Lanes project, also known as the LBJ Express, was a USD$2.7 billion, 22 kilometres highway reconstruction that more than doubled the capacity of the existing corridor. It is the largest significant transportation improvement project in northern Texas (USA), with the goal to relieve severe congestion along the I-635 and IH-35 in a dense urban area of Dallas. The LBJ Express project has over half million square metres of deck, as large as 120 football fields, more than 5,700 precast beams, 100 km of piling, and over 300,000 square metres of retaining walls with 7 million cubic metres of earthworks, this article presents the innovative design approach and the accelerated bridge construction techniques implemented for the structures, which was an exceptionally complex project. Through the use of innovative structural solutions for the bent caps (headstocks) and straddle bents (extended headstocks), skilled design optimisation, and careful construction analysis, including the ad-hoc design of launching gantries, the team was able to accelerate the bridge construction ensuring traffic flows in excess of 270,000 vehicles per day.

Application of Novel Recovery Techniques to Enhance the Resilience of Transportation Networks

Resilience is an important characteristic of the transportation system. It reflects the network’s ability to mitigate shocks, provide alternatives, and rapidly recover to a target performance level. Earthquakes can cause the transportation network to experience severe disruptions that significantly reduce network resilience. To prevent long-term closures after earthquakes, the development of innovative approaches for their rapid restoration is necessary. This paper uses the recent developments in accelerated bridge construction (ABC) techniques as a means to enhance the rapid recovery of the system. ABC techniques often come with increased initial construction costs. In most cases, the additional cost is offset by the improvement of the network performance. To examine the efficiency of ABC techniques on the rapid recovery and on the network performance after earthquakes, the direct and indirect costs during the entire recovery period were analyzed and the relationship between network recovery time and network performance was estimated under different construction techniques. Additionally, the effect of using the incentive method to reduce the repair time was studied. The results show that the use of ABC techniques and the incentive method have great potential to minimize the transportation network’s indirect losses, improve network performance, increase the network’s resilience by decreasing recovery time, and justify the additional initial costs associated with these techniques.

Sustainable production of precast combined pile-cap and column elements via statistical analysis of self-compacting concrete kinetics

This research applied accelerated bridge construction techniques to the Northern Mexico City Elevated Urban Toll Road. To this end, an 18-m precast combined pile-cap and column element was monitored during production. The recorded high internal temperatures raised concerns, which led to the extraction and testing of concrete cores, yielding satisfactory strengths. The kinetics during the setting and hardening of the three high-strength self-consolidating concrete mixes used in the production of these elements was statistically validated for the temperature range from 4.5 to 88 °C. In a previous study, new maturity functions were developed to predict the strength of equivalent mortars as a function of both the hardening time and isothermal curing temperature, which accounted for the crossover effect and provided better compressive strength predictions than ASTM C1074-11. These functions were applied herein to optimize the production, select the optimal concrete mix, and minimize the total construction time and environmental cost.

Performance Evaluation of Longitudinal Ultrahigh-Performance Concrete Closure Pour Connection for Use in Modular Bridge Construction: Pairwise Comparison of Capacity and Ductility at Failure Limit State

Accelerated bridge construction techniques taking advantage of prefabricated bridge elements and high-performance materials are being used more frequently for bridge replacement projects. They result in minimal road closure times and traffic interruption and in the reconstruction of long-lasting highway bridges. Longitudinal closure pour connections are an important deck-level component for modular bridge elements that are heavily stressed by traffic loadings and environmental effects and whose durability is a concern. To address cracking and leakage issues in such connections, the strength and failure modes of the longitudinal ultrahigh-performance concrete (UHPC) closure pour connection between adjacent prefabricated deck units were evaluated. First, specimens with and without a longitudinal UHPC closure pour connection were fabricated, instrumented, and tested. Finite element (FE) models were established to improve understanding of the behavior of the specimens under the loading condition. In addition, strut-and-tie models (STMs) were developed on the basis of FE model predictions to estimate the strength of the specimens. The jointed specimens were found not to have any cracks or leakage at the early stage but had lower cracking loads than did the jointless specimens. The strength and ductility of the jointed specimens were comparable with those of the jointless specimens. On the basis of the FE models and STMs, the ultimate strength of the specimens was accurately predicted.

Strut-and-tie models of repaired precast concrete bridge substructures with CFRP shell

Strut-and-tie models (STM) have been developed for original and repaired precast reinforced concrete (RC) bridge assemblies tested under quasi-static cyclic loads. The original assemblies, built using accelerated bridge construction techniques, are half-scale column-to-footing and column-to-pier cap specimens connected using grouted splice sleeves. The repaired assemblies are strengthened over the plastic hinge region using a unidirectional carbon fiber reinforced polymer (CFRP) shell, post-installed headed steel bars, and non-shrink concrete. The repair technique was successful and the load and displacement capacities of the damaged assemblies were restored. Generic modeling parameters are established for the STM procedure, enabling the models to be adapted to new repair applications. Special attention is focused on the struts within the CFRP shell. All assemblies are modeled using sectional analysis in conjunction with the predicted STM load to estimate a bilinear force–displacement response. The STM and bilinear force–displacement response envelopes obtained from the models show satisfactory agreement with the experiments of the original and repaired bridge assemblies in terms of initial stiffness, lateral load and displacement capacity.

Decision Making and Economic Analysis for Accelerated Bridge Construction

Accelerated Bridge Construction (ABC) is recognized as an important method to design and rehabilitate highway bridge structures. ABC is bridge construction that uses innovative planning, design, materials, and construction methods in a safe and cost-effective manner to reduce the onsite construction time that occurs when building new bridges or replacing and rehabilitating existing bridges. ABC uses both new technology and innovative project management techniques to reduce the impact of bridge construction projects on the public and to reduce bridge construction costs. In the early stages of a construction project, engineers need to assess whether elements of ABC are achievable and effective for a specific bridge location. Use of decision-making tools in early stages of planning is advocated as a mechanism for helping decision maker assess alternatives with more confidence and for preventing investment in alternatives that are more costly. In this study, a set of decision making tools, based on the Bridge Construction Index (BCI) were developed. This tool is prepared for transportation specialists and decision-makers to determine if ABC techniques are more effective than traditional construction for a given bridge replacement or rehabilitation project.

A decision tool for accelerated bridge construction

Accelerated bridge construction, which includes the application of innovative technologies and management techniques, is considered an important method for construction and rehabilitation of highway bridges. It mitigates the effects of bridge construction on the public and reduces construction costs. In this paper, a tool set based on the analytic hierarchy process is presented to help transportation decision-makers determine the effectiveness of accelerated bridge construction in comparison with traditional construction for a given project. The authors present a literature review on accelerated bridge construction techniques, decision-making approaches and other related topics, and they develop a comprehensive criteria hierarchy for a bridge construction or rehabilitation that they incorporate into a software tool.

Performance of Posttensioned Curved-Strand Connections in Transverse Joints of Precast Deck Panels

Accelerated bridge construction techniques have resulted in state-of-the-art options that save time and money during the construction of new or existing bridges. One such group of techniques that has generated considerable interest is the use of precast-concrete deck panels. Using precast-concrete deck panels allows for off-site curing, thus eliminating long delays from formwork construction and concrete curing time. Despite the benefits, problems can develop as a result of the inherent joints between the individual panels. These joints are locations for potential leakage, which can result in corrosion or inadequate long-term performance. Posttensioning the precast deck panels helps to eliminate leakage, but conventional longitudinal posttensioning systems require complete deck replacement in the event of a single faulty deck panel. The proposed posttensioned curved-strand connection presented in this paper allows for single-panel replacement. The capacity of the proposed curved-strand connection was investigated to compare its behavior with that of other systems currently in use. The curved-strand connection was found to be comparable to a standard posttensioning system. The ultimate capacity of the curved-strand connection in negative bending was found to be 97% of the standard posttensioning connection.

One-Weekend Job

As part of a national initiative sponsored by FHWA under the Highways for LIFE program, the Utah Department of Transportation (DOT) was awarded a $1 million grant to demonstrate the use of proven, innovative technologies for accelerated bridge removal and replacement. This report documents accelerated bridge construction (ABC) techniques used to remove and replace the 4500 South Bridge on State Route 266 over Interstate 215 in Salt Lake City during a weekend. It includes construction details of the bridge superstructure built offsite on temporary abutments and prefabricated and cast-in-place bridge components and substructure built under the existing bridge without interfering with traffic flow. It also discusses use of a self-propelled modular transporter (SPMT) to remove the old bridge and to replace it with a new one. With conventional construction, the impact of this project on the traveling public was estimated at 120 days, but with accelerated construction techniques the impact was reduced to a single weekend for I-215 and 10 days for State Route 266. Using an SPMT and other ABC techniques added about $0.81 million to the initial construction cost of the project. However, a more comprehensive economic analysis including user cost savings shows that the project saved road users about $3.24 million (or about 36% of the total project costs). Because of the success of this project, the Utah DOT has decided to use ABC techniques more routinely in future projects and has set a goal of making ABC standard practice for all bridges by 2010.