In this paper an empirical formula of slip stress for verification of slip capacity of expansive stressed grouted clamp is proposed. The influence parameters on the slip stress are studied, including the content of expansive agent, the slenderness ratio L/D, the ratio of thickness to diameter of damaged tube T/D and the surface condition. Using the test data of two different sizes of clamp models, the parameter coefficients of the empirical formula are analyzed. Parameter optimization method is also used to fit the experimental data. It is shown that the predicted values by this formula are in good agreement with the experimental data, and the error range is within 10%.
The stressed grouted clamp is a common selection for repairing and strengthening damaged component of offshore structures. It has been widely used possessing the advantage of a high tolerance of imperfection and good fatigue properties for repairing steel tube in offshore constructions (Grundy and Foo, 1991; MSL Engineering Ltd, 2004). But the traditional type clamp with long stud bolts has to confront the disadvantage of complicated underwater operations and high related cost. Based on the rapid development of special property concrete technology, the expansive stressed grouted clamp is recommended due to its easy installation and low cost because that its self-stress is established automatically by expansive grout instead (Shi et al. 2010). Then tests of long-term models after 1 year of maintenance are carried out by Shi et al. (2013). It is reported that the expansive stressed grouted clamp has a good durability and load capacity, so it is suitable for underwater repair and reinforcement of offshore constructions. Yuan et al. (2013) reported that the expansive stressed grouted clamp with short bolts, possessing advantages of low steel consumption and more easy installation, was found to produce relatively larger expansive pressure and obtain a larger slip stress. And the slip capacities of the short-bolt-type expansive stressed grouted clamps were tested under different agent contents and different slenderness ratios (Shi, et al., 2015). Zhang et al. (2016) summarized the design method of expansive stressed grouted clamp on a joint of a jacket platform. Zhu et al. (2108) supplemented the design method of expansive stressed grouted clamp assessing the modified stiffness and the increased environmental loads. Shi et al. (2108) tested the capacity properties of real-size expansive stressed grouted clamps.