High strength bolts of grade 8.8 are commonly used to function as ordinary bolts. Two problems arise. Firstly, no design guidance is given in the Egyptian code of practice for the use of grade 8.8 bolts when tightened by hand spanner. Secondly, there is no Egyptian standard that specifies the properties of grade 8.8 bolts' material. This paper assesses the strength values of grade 8.8 bolts available in the local market and manufactured at different countries. An experimental programme was carried out. The bolts were subjected to direct tension and shear until failure. All the bolts satisfied the tensile strength requirements of the ISO 898 - 1 and the BS 3692. The bolts exhibited inconsistent shear strength values. The safety factor against failure in shear is found less than that in tension and less than that of other structural members. This highlights the need of defining the shear strength in the codes of practice. The results obtained are compared to other experimental data presented in the literature. The design guidance in the Egyptian codes and BS 449 is reviewed. The use of grade 8.8 bolts when tightened by hand spanner is discussed. The compatibility of grade 8.8 bolts with other ordinary bolts allowed in the Egyptian code is studied. |
