International Concrete Abstracts Portal

Most engineering professionals have been educated and trained to appreciate and use a scientific orientation in their specialty. Scientific orientation means an orientation or habit of mind that continually compels and provokes one to reexamine, evaluate, and improve his or her symbolic representations of reality. However, for some situations and in certain circumstances, some professionals, either through neglect or inattention, base their beliefs, decisions, practices, and policies on idealizations that have a tenuous relationship to reality. Consequently, some of their actions are based on flawed assumptions, assumptions that are partly responsible for their questionable decisions and the poor performance of their designs. This is especially true when considering inadequacies that are everywhere evident in the design and construction of bridge deck joints and bearings. This paper describes and discusses a number of flawed assumptions, assumptions made by technicians, novice engineers, supervisory engineers, design administrators, and entire transportation agencies. It urges a greater awareness of reality as the most effective way to appreciate the disparity between the ideal and the real. Such an appreciation will lead to an improvement in basic assumptions, to an improvement in the performance of individuals responsible for design, and ultimately to an improvement in the performance and durability of the structures produced for transportation systems.

Buried joints are frequently used in small and medium span bridges because they are serviceable and comfortable. This paper illustrates a theoretical method and an experimental equipment setup for the study of buried joint systems, in particular to evaluate the influence of some parameters that affect their fatigue life, with the aim of supplying references for the design of new optimal buried joint systems. The theoretical analysis is developed by applying a calculation method set up at the Department of Transportation Engineering of the University of Naples "Federico II" (D. I. T.). The results of this analysis are discussed; some interesting indications for the design of buried joints based on these results are given. As for the experimental study, this paper also describes a prototype equipment for testing the buried joint systems, evaluating their capability to reduce the deformations and to increase, therefore, the fatigue life. The equipment had been purposely designed and set up at D. I. T. Some experimental tests have been conducted using this equipment. The results of the tests have confirmed the validity of the design method developed.

The first application of Base Isolation within the European Union dates back to 1974, when this design approach was adopted for the Somplago Viaduct in Italy. The numerous solutions adopted since that time are based upon different functioning principles and the use of various materials. There are substantial differences between the classes of devices used in new projects or in cases of retrofit projects. Nonetheless, all have an essential characteristic in common: the elements which transmit vertical loads (bearing devices) are clearly distinct from those that control horizontal loads resulting from either seismic or service actions (re- centering/dissipating devices). In this manner, certain important advantages, which the paper illustrates in detail, can be gained. In addition, as it concerns the case of retrofit projects, the solutions adopted in order to insure the structure's seismic protection are so implemented as to not alter the original restraint scheme, i. e., the fixed and expansion points are not changed. Thus, the structure responds to service loads in the manner conceived by its original designer. This paper illustrates these concepts through the illustration of some particular cases.

Over the past decade, isolation bearings have seen a dramatic increase in usage on civil engineering structures. In the early stages, specifiers relied heavily on manufacturers when it came to composing material properties, performance standards, and testing requirements for these devices. The current state of the art dealing with isolation bearing specifications is much further advanced. However, several issues remain confusing to engineers wishing to implement isolators either for seismic or force control design rationale. This paper attempts to simplify isolation bearing specification issues by identifying important design criteria. Items such as qualification, material properties, fabrication, inspection, and testing concerns are all important components in a well-structured document.

Effective sealing of expansion joints in parking structures requires a thorough understanding of structural behavior and the service condition, as well as the properties and limitations of available expansion joint systems. Factors contributing to volume change, traffic conditions, detailing, and installation will all play a role in the ultimate success of the joint system selected. Commercial types of expansion joint seals commonly available include the urethane "T" joint, compression seals, steel and aluminum strip seals, winged seals with headers, and inflated structural seals. Each have certain advantages and limitations which must be considered relative to the usage condition in order to make a proper selection. Detailing considerations, such as joint opening size, movement considerations, traffic volume and loading, directional change, and termination requirements and drainage patterns all have an impact on performance. Periodic maintenance should be expected and planned for through an established program. Today, a wide variety of effective expansion joint sealing systems are available to help avoid the many problems previously associated with parking structure applications. Success depends on understanding the requirements of the service condition and the limitations of the various systems considered for use. Only with care in the specification and detailing of expansion joint requirements at the design stage will the installing contractor be positioned to most effectively install any expansion joint system.