Selecting Suitable Bolt Parameters to Achieve Ductility at Elevated Temperatures

A detailed FE study is presented investigating the factors affecting failure modes of bolt assemblies under tensile force at ambient and elevated temperatures. Axisymmetric FE models incorporating important behavioural aspects including surface interaction and damage modelling were developed. Stripping failure is generally undesirable because it results in premature failure of the bolt, which can deteriorate the rotational capacity of connections and robustness of steel frames. The paper discusses how the thread length in the grip L t can affect the failure mode of bolt assemblies at elevated temperatures. This paper concludes that at ambient temperature, stripping can occur at certain L t length dependent upon the nut dimension deviation from the basic profile; this length reduces with temperature.