International Concrete Abstracts Portal

Tests for four circular segmented tunnel linings are described. Two single-ring specimens had the conventional flat joint and the tongue-and-groove joints at the key segment. The three-ring specimens used a staggered arrangement and had circumferential joints with and without tongue-and-groove configurations. The load was applied from the top and the side wall on the single-ring specimens. The measurements of overall deformation, joint slip at the key segment, and joint opening were used in studies of waterproofing joints of several linings. The type of joint configurations that has been proven satisfactory is the key segment with the tongue-and-groove for the longitudinal joint. This selection is based largely on economic factors. Documented field cases observed in the underground excavations carried out for the electric utility tunnels in the urban areas were presented to investigate the applicable watertightening joint of segmented linings.

The state of the art in the design of pot bearings and, in particular, the relationship between the stress condition in the pot and the adjacent structure are overviewed. The difficulties encountered in performing precise calculations are discussed. Safe and simple design criteria are obtained through the analysis of the ultimate state. The most recent research programs on bearing plates, the factors relevant to the stress condition under the distribution plate, and deformations are reported. Formulas for the design of the pot and the distribution plate are given. The transmission of horizontal forces through the bearing is analyzed. The necessary formulas are presented as well as current values for friction between various materials and the strength of typical shear connectors in use. A bibliography covering many aspects of the theoretical and practical research performed on this subject concludes the paper.

Through the course of history, bridge engineers have been plagued with problems resulting from kinematic dilations and displacements, particularly on longer spans, and curved and skewed structures. Numerous variations of expansion joint devices have been utilized, but the earliest and most popular large movement system has been the finger or tooth joint. This paper explores the origins of the finger-type expansion dam and traces the evolution of this system to its current state-of-the-art designs for bridges in North America in an effort to determine the adequacy of finger joints. The cost effectiveness of these devices is equated in terms of ridability, drainage, durability, protection of the span ends and substructure, and ability or inability to transmit rotation and abnormal movements. Customary problems such as repair of exposed and fatigued finger plates and removal of impacted debris from drainage pipes and troughs are illustrated. Numerous other types of large movement expansion devices such as slider plates, rubber cushions, and modular systems have been installed on structures with various degrees of success. A comparison of these types of mechanisms to that of the finger dam is portrayed to equate performance of both. Some design authorities have begun to require more advanced types of expansion devices while others have continued to utilize finger joints. This paper also attempts to determine the reasons for these decisions as they apply to contemporary structures. Finger joints have undergone a multiplicity of variations in design throughout the course of their history on bridges. However, the fundamentals and performance shortcomings have remained the same on all of these devices. It is the intent of this document to inform the design engineer in this field of expertise.

The Third Lake Washington Bridge floats between Seattle, Wash., and Mercer Island on Lake Washington. The length of this structure is approximately 2« miles and because this structure floats, it is subjected to the rise and fall of the lake water level and wave action. The result is a complexity of movement. These movements are 48 in. (1219 mm) longitudinally, The vertical deflection is 2 deg or 15 in. (381 mm) across the joint system, and the horizontal or transverse rotation is 1 deg. These parameters initiated the most sought-after design competition for a sealed expansion joint in history. Three alternate designs were proposed. The State of Washington's Department of Transportation Bridge Design Group selected a joint venture in which the authors participated. This paper discusses the movements of the bridge and the design of the selected expansion joint system.

The historical development of using bearings in Ontario and the current design requirements contained in the Ontario Highway Bridge Design Code and the Ministry's bearing specifications are reviewed. Numerous instances of unsatisfactory bearing performance, especially of proprietary rotational and sliding bearings, are described. Examples are given of unsatisfactory performance resulting from poor bridge design practices, improper bearing design, poor manufacturing procedures, and incorrect installation. In all cases, the action that has been taken to prevent a recurrence of the deficient performance is presented. The basic philosophy in design is to use the minimum number of bearings consistent with the articulation of the structure. The severity of the service environment has been recognized with the result that a high degree of corrosion protection is specified and a provision made for bearing replacement. All bearings are required to have a capacity for rotation about all three axes, which means that rockers, rollers, sliding plates, and cylindrical bearings are no longer used. The paper also describes the contractual relationships involved in the supply of highway bridge bearings and concludes that while a performance specification and guarantee would be desirable, such an approach is not practical.