Precast concrete segmental bridges with dry joints have the advantages of rapid construction speed and low cost. The shear strength and shear behavior of dry joints with castellated keys in precast concrete segmental bridges are still debatable. In this paper, full-scale dry joints with castellated keys were tested under different confining stress levels. The main parameters for tests were the number of keys, the confining stress, the depth in key geometry, and the distance between two keys. For comparison purposes, flat joints, monolithic joints, and joints with steel fibers were also tested. The shear behavior, shear capacity, and crack pattern of the joints were investigated as well. Two crack modes for the single-keyed joints are explicitly proposed. The phenomenon of sequential failure of multikeyed dry joints from the inferior key to the superior one was observed in the tests and verified by finite-element simulation. The experimental results obtained in these tests were compared with the design provisions. A shear failure mechanism of sequential failure for multikeyed dry joints is presented to explain the differences between the test results and the formula used. Based on the new explanation and test results, a reduced coefficient of 0.7 is recommended for the shear strength of three-keyed dry joints. Pending more test data, this conclusion could be extended to the shear strength of multikeyed dry joints to improve the formula.

Dry joints represent locations of discontinuity in precast concrete segmental bridges (PCSBs) through which compressive and shear stresses must be transmitted. Cracks in dry joints occur more easily than those in epoxy joints during the construction period or in service. Steel fiber-reinforced concrete (SFRC) with high rupture strength might be beneficial to the shear resistance of dry joints. In this study, shear behavior of various types of dry joints in PCSBs was investigated by experiments, especially focusing on shear strength of keyed dry joints of SFRC. The experimental parameters were joint types, concrete types, key numbers, contacting portions in the sliding plane, and horizontal confining stress levels. Cracking loads, cracking patterns, failure modes, and ultimate loads were recorded. Normalized shear stress-vertical slip curves and load-horizontal dilation relationships have been investigated. It can be concluded that the use of SFRC can improve shear strength and ductility of dry joi...

This 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 that is cast and prestressed with the girder provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, 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 a perceived problem with durability of longitudinal joints used to connect adjacent girders. This paper presents the results of a study to assess potential alternate joint details based on constructability, followed by testing of selected details. Seven reinforced concrete beam specimens connected with either lapped headed reinforcement or lapped welded wire reinforcement were tested along with a specimen reinforced by continuous bars for comparison. Test results were evaluated based on flexural capacity,...

A theoretical method, termed the mesoscale fiber-matrix discrete model (MFDM), has been developed that can be used for estimating the shear contribution of steel fibers and calculating shear strength of ultrahigh-performance fiber-reinforced concrete (UHPFRC) beams. In the proposed model, an effective fiber distributed region (EDR) along the critical diagonal shear crack, where fibers are efficient at providing shear resistance, is defined. The total quantity of fibers within EDR is calculated by the EDR volume proportion of the beam based on a uniform distribution of steel fibers. Two concepts to determine the width of EDR are proposed: (1) probability theory and (2) the basis of the pullout load slip relationship. The bond strength between a single fiber and the matrix is determined by the probability method based on a uniform distribution of fibers. Combining the number of efficient fibers and the bond strength of a single fiber, the shear contribution of fibers is derived. The shear contributi...