Steel H-piles have been used widely in bridge construction throughout the U.S. because of their relatively large load-carrying capacity while occupying a small area. However, many H-piles suffer from corrosion, which may lead to abrupt collapse. A cost-effective repair technique, including encasing the corroded region of the steel pile into a concrete jacket, which acts as an alternative load path for the applied axial load, has been used by several state Departments of Transportation. Methyl methacrylate polymer concrete (MMA-PC) is a type of concrete that is commonly used as a repair material. However, there is limited research on the assessment of bond strength between MMA-PC and steel elements. This paper investigates experimentally the bond behavior of seven full-scale steel H-piles encased in concrete jackets. The jackets were cast using either MMA-PC or Portland cement concrete (CC). Different embedment lengths of 63.5 mm (2.5 in.), 127 mm (5 in.), and 190.5 mm (7.5 in.) were used for the MMA-PC and one embedment length of 254 mm (10 in.) was used for the CC jacket. Cylindrical and prismatic jacket configurations were used and tested using push-out. The experimental results revealed that using the MMA-PC jacket was more effective compared with the CC jacket in relation to the load-carrying capacity. For design purposes, a shear bond stress of 2.96 MPa [0.43 kips per square inch (ksi)] can be used for MMA-PC jackets having an embedment length of at least 127 mm (5 in.) whereas a value of 0.83 MPa (0.12 ksi) can be used for CC.
A paper round robin was conducted to evaluate the workability and reproducibility of a unified draft fracture toughness test standard titled “Standard Method for Measurement of Fracture Toughness.” The paper round robin consisted of 19 records from fracture toughness tests conducted separately from this round-robin exercise. These test records were given to the participants with the requirement that they use the draft standard to evaluate the fracture toughness values from the tests. The round robin was conducted between February 1991 and June 1992. Originally more than 30 organizations were invited to participate; however, only five finally responded with complete analyses of all of the test records. The five participants were all experienced in fracture testing and analyses. To subject the method to an evaluation by persons with less experience, some of the test records were analyzed by graduate students whose only experience with fracture testing and analyses was a course on fracture mechanics.
The round robin was conducted on Draft 10 of the proposed standard: “Standard Method for Measurement of Fracture Toughness” This paper contains a brief description of the draft test method, a discussion of the specimens and test records supplied, a brief summary of results, and a discussion of the changes made to the test method as a result of the round-robin exercise. All tests and analyses were conducted using English units; therefore, to accurately transmit the results, English rather than SI are used as the primary units of this report.
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