Can I tighten A325 and A490 structural bolts by turning the head of the bolt?
Yes. Per the RCSC Specification for Structural Joints Using High-Strength Bolts (2014), section 8.2, it says:
“When it is impractical to turn the nut, pretensioning by turning the bolt head is permitted while the rotation of the nut is prevented, provided that the washer requirements in Section 6.2 are met”
