A practical problem with threaded rebar bolts in reinforcing largely deformed rock masses

The practical problems or failure with threaded rebar bolts are presented to become aware of the direction to enhance the load-bearing capacity of rebar bolts when needed. The loading condition of the bolt is examined for the purpose of showing how much the thread reduces the loading capacity of the bolt. The nature of the bolt failure could be ductile or brittle, depending upon the loading condition the bolt is subjected to. The brittle failure is characterized by a clean failure plane without occurrence of the necking phenomenon. The thread and the steel bar may be at different stages of deformation when the thread undergoes failure. The elongation of the bar linearly increases with the tensile load until the load reaches the yielding limit of the steel. Rebar bolts usually fails at the thread in largely deformed rock masses, and so an enlarged thread or headed rebar bolts can be considered as a substitute of the conventional rebar bolt.