Mohiuddin Ali Khan

Rapid Bridge Insertions Following Failures

Transportation bridges are an essential part of a network of highways and provide continuity to their use for rapid travel. If a bridge is shut down, it has many adverse consequences. This chapter covers topics relating to bridge failure and rapid construction techniques. Numerous incidences of recurring damage and failures in the conventional system of design and construction are demonstrated in this chapter, requiring a review of the design and construction philosophy. An alternate accelerated bridge construction (ABC) system with prefabrication and preassembly is proposed to overcome the difficulties. The difficulties are in transportation to the site and the availability of high-capacity cranes. The use of prefabricated girders is also on the rise, and the conventional system has been modified to a partial ABC system. It is expected that due to the increased popularity and many advantages of ABC system, the partial ABC system will be a good place to start, leading eventually toward full ABC.

Introduction to Modern Accelerated Bridge Construction

With the advent of high-capacity machinery, new materials, and new management methods, we are now able to manufacture bridge assemblies and lift them in position. There is a year-round need for infrastructure improvements and maintenance in the form of rapid replacement and rehabilitation of many thousands of bridges. Although most of us have heard the expression accelerated bridge construction (ABC), few of us know the intricate details. In this book, an attempt is made to bring up to date the latest knowledge of the multibillion dollar construction industry. The topics in this introduction cover the need for ABC, differences in conventional methods, the state of the art, the scope of work, and the many advantages and existing constraints in achieving rapid delivery. Funding limitations, review of progress in other structural disciplines, notable ABC projects being built in several US states, recommendations, and the need for a code of practice for accelerated construction are addressed. Applying the ABC methodology will result in 50% greater number of completed bridges each year. It will help the economy by reducing wasted hours due to traffic jams during construction, helping commuters to work, and also benefiting commerce by increasing faster delivery of goods.

A Review of Chapters, River Bridges, and Conclusions

This final chapter is divided into two parts. Part 1 is a summary and review of the first 10 chapters of the book. Part 2 is concerned with rapid bridge construction on rivers, using an alternative float-in method to transport the assembled bridge to the bridge site. Since scour is the most common reason for the failure of highway bridges in the United States, the different types of scour are discussed, and then the latest technologies for scour countermeasures are introduced. Bridge inspections and condition ratings are outlined, as well as structural countermeasures. Several case studies of bridge reconstruction are given. The chapter concludes with a detailed outline of the reasons for extending the used of accelerated bridge construction (ABC) to highway bridges.

Prefabrication of the Substructure and Construction Issues

This chapter discusses rapid construction applications for the bridge substructure and foundations. The substructure, totally prefabricated bridges, and emergency replacement of the existing substructure (when the superstructure is lifted off the top of bearings and reused) using precast units are addressed. A list of successful substructure projects that were completed in recent years in different states is provided, along with case studies and detailed discussions on substructure construction.

Innovative ABC Techniques

The prime factors needed to meet the objectives of accelerated bridge construction (ABC) are materials, prefabrication, training, and construction equipment and early warning systems. In terms of materials, there has been a revolution in modern concrete technology and the precasting industry. The new concrete materials comprise of a variety of amazing high-strength materials, minimizing the dependence on diminishing steel. The Federal Highway Administration has championed the ABC time savings provided by using prefabricated bridge elements and systems, which include precast deck and prefabricated superstructures. Training courses and workshops in ABC are offered by organizations such as the American Society of Civil Engineers and the Structural Engineering Institute, and considerable information on important ABC aspects is available on transportation research websites. Such information and training are vital to keep pace with the many new ABC technologies. For example, there is a “smart paint” that outlines a fatigue crack in a bridge as it propagates and can evaluate fatigue in old bridges more accurately than strain gauges. Such new technology can serve as an early warning system.

ABC Planning and Resolving ABC Issues

The infrastructure difficulties faced by the public are highlighted in this chapter, and the economic and public comfort benefits derived from early completion of projects are reviewed. Bridges are a sensitive part of any highway system, and their importance is based on the network of highways that they serve and the average daily volume of traffic. A bridges relative importance determines the funding allocation and priority of its repair. Accelerated bridge construction (ABC) can assist in the timely completion of bridge projects. The steps of ABC methodology are discussed herein. This chapter outlines the successful ABC projects completed by many states. Partial ABC for rehabilitation of existing bridges can also be implemented. The restrictions to partial ABC in these scenarios are discussed in this chapter, along with the options available for the design of new or replacement bridges.

Alternative ABC Methods and Funding Justification

Replacement or repair of bridges throughout the United States must be done on a priority basis so that traffic flow will not be adversely affected. This chapter advances the concepts of accelerated bridge construction (“ABC”) discussed in earlier chapters, with an emphasis on analytical terminology to facilitate structural condition evaluation. Methods for evaluating the structural and functional condition of bridges are described. Policy making, the scope of reconstruction, selecting economical alternatives, and the use of modular bridges are also emphasized. Innovative techniques and new applications given in earlier chapters are further expanded. Case studies of successful ABC projects by selected states using self-propelled modular transporters or lateral slide-in methods are presented. Essential funding needs, value engineering, and alternate solutions such as public–private partnerships are discussed.

Prefabrication of the Superstructure

Prefabrication of the bridge superstructure is the most important aspect of the accelerated bridge construction (ABC) method. This chapter discusses the prefabrication of the superstructure. A list of successful projects completed in recent years in different states is presented. Other issues covered in this chapter include a wider use of the P3 system and the use of a high-friction deck surface to prevent rusting of rebars.

Modular Bridge Construction Issues

Modern technology in construction techniques has provided new avenues of prefabricated bridge element production. In this chapter, the latest trends and the many advantages of purchasing ready-made bridges by using prefabrication methods are addressed, as well as associated construction issues. Superstructure applications adopted by various states include steel girders, trusses, and precast concrete I shape and box girders according to design requirements and availability for speedy construction. Prefabricated bridge elements and systems (PBES) are manufactured off-site, ready for installation when they are brought to the construction site. Bridge elements are the basic building blocks of bridge construction, such as deck panels, girders, pier caps, columns, pile cap footings, and foundations.

Recent Developments in ABC Concepts

Design, construction, and repair of bridges is an ongoing challenge. This work must be carried out in both a correct and timely manner, for the sake of both public safety and those responsible for these structures. ABC concepts provide a valuable guide for bridge design, manufacture, construction, and management. Crucially important is recognizing the potential for bridge failure, resulting from scour and erosion, outdated procedures and technologies, and sometimes negligence. A close look at management issues and ABC applications will help clarify the best approaches to avoiding pitfalls and preventing bridge failure and its devastating consequences. Topics examined in this chapter include identification of deficient bridges, accelerated bridge rehabilitation, surveying scour countermeasures for bridges over rivers, and developing a field reconnaissance form, as well as obtaining funding for this critical work. Resources are recommended that include federal and state agency and construction industry-supported publications, many of which advocate the use of ABC.