Clause 10.2 specifies the minimum requirements for spacing, edge distance, and arrangement of bolts in structural connections. These rules ensure proper load transfer, prevent premature bearing failure, and provide adequate space for bolt installation and tightening.
Key Requirements
•Bolt hole diameter = bolt diameter + 2 mm for standard clearance holes (Cl. 10.2.1)
Maximum edge distance to prevent buckling of outstanding plate portion
t = Thickness of the thinner connected plate (mm)ε = √(250/fy)
Practical Notes
✓For M20 bolts (most common in Indian steel construction): minimum pitch = 50 mm, minimum edge distance = 37 mm (sheared) or 33 mm (machine-cut). A typical gauge of 60–70 mm and pitch of 50–60 mm works well.
✓When detailing, always check that there is enough space for a standard wrench or spanner. Minimum clearance for a standard hex nut on M20 bolt is about 45 mm between bolt centres.
✓For connections exposed to corrosive environments, use the tighter maximum pitch limits (16t or 200 mm) from Cl. 10.2.3.2 to prevent crevice corrosion between plates.
Common Mistakes
⚠Using bolt diameter instead of hole diameter when calculating net area — the hole (bolt + 2 mm) is what removes material.
⚠Providing edge distance less than 1.7 × hole diameter for sheared edges — this can cause bearing failure or edge tear-out.
⚠Exceeding maximum pitch limits — wide bolt spacing allows plate buckling between bolts and corrosion in gaps.