Introduction

The methodology used for fatigue design of bolted connections that are subjected to dynamic loading is rather old. This becomes clear when studying the third edition of the book on design of bolt connections by Wiegand and Illgner (1962); this book was first issued in 1940, and in the 1962 third edition, among the 254 references provided, the oldest one dates back to 1908. However, the main span of references is from 1930 to 1960.

In the Handbook of Bolts and Bolted Connections, edited by Bickford and Nassar (1998), it is stated that: “The bolted joint is a surprisingly complicated affair.” Although many factors affect its behavior and life, the design of most joints is based on “feel,” supported by “past experience” or “custom.” Because of this, most joints are overdesigned. Nevertheless, due to the uncertainties, it may be considered sound practice to make the joints stronger than the members. Many books and standards on bolted connections have been published; compared with some of these weighty books, the quantity of recommendations that can be written into this single chapter in this book is limited. Thus, this chapter should be considered more as providing an overview, and for more detailed studies, the reader should see other literature, such as the Handbook mentioned earlier, as well as Kulak et al. (1987). A number of ISO and ASTM standards can also be consulted regarding notations, production of bolts, tolerances of bolts, washers, and nuts, mechanical properties, testing, and documentation.

The terminology used for fasteners is presented in ISO 1891 (2009). Fasteners are understood to encompass bolts, and include head bolts that have threads for a nut at one end and stud bolts with threads at both ends and an unthreaded shank between them. The shank between the head and the threaded section of a stud bolt is also called a grip length, and the bolt diameter refers to this part of the bolt.

A number of bolt failures occurred during the first years of offshore activity in the North Sea. This resulted in stricter requirements for bolt design, fabrication, installation, maintenance, traceability, and quality assurance. The design of bolts in marine structures was found to require special attention regarding corrosion protection and dynamic loading. Due to the dynamic loading, it is recommended that bolts are pretensioned, as these bolts are most effective with respect to fatigue capacity.