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Steel Section Index

Bolt Holes centres for sections



Introduction

The back mark is the distance from the back of an angle or channel web to the centre of a hole through the leg or flange.     This dimension is selected taking into account, access for tightening the bolt using an appropriate spanner, being close to centroidal axis ,and provision of required edge distance    The distance between centres of holes in flanges of joists, universal columns and Universal beams is selected to provide accessibility and acceptable edge distance.

All Dimensions in mm

Maximum recomended bolt sizes shown in brackets

Recommended Bolt Back Marks in Channel Flanges

dimensions in mm




Nominal Flange Wdith
S1
Back Mark
Edge Dist
Recommended Bolt dia
102
55
47
24
89
55
34
20
76
45
31
20
64
35
29
16
51
30
21
10
38
22
-










Recommended Bolt Back Marks in Angle Sections




All Dimensions in mm

Maximum recomended bolt sizes shown in brackets



Nominal leg S1 S2 S3 S4 S5 S6
25 15 - - - - -
30 20 - - - - -
40 23 - - - - -
45 25 - - - - -
50 28 (12) - - - - -
60 35 (16) - - - - -
65 35 (20) - - - - -
70 40 (20) - - - - -
75 45 (20) - - - - -
80 45 (20) - - - - -
90 50 (24) - - - - -
100 55 (24) - - - - -
120 - 45 (16) 50 (16) - - -
125 - 45 (20) 50 (20) - - -
150 - 55 (20 ) 55 (20) - - -
200 - 75(30) 75(30) 55 (20) 55 (20) 55 (20)



Recommended Bolt Centres for Column/Beam Flanges



All Dimensions in mm

Maximum recomended bolt sizes shown in brackets

Flange width Min. for
Accessiblility		 Maximum for
Edge dist		 S1 S2 S3 S4
Joists
44 27(5) 30 30 - - -
64 38(10) 39 40 - - -
76 48(10) 51 48 - - -
89 54 (12) 59 56 - - -
102 60 (16) 62 60 - - -
114 66(16) 74 70 - - -
127 72(20) 77 75 - - -
152 75(20) 102 90 - - -
203 91(24) 143 140 - - -
Universal columns
152 65 (24) 92 90 - - -
203 75 (24) 143 140 - - -
254 87 (24) 194 140 - - -
305 100 (24) 245 140 120 (24) 60 (24) 240 (24)
368 88 (24) 308 140 140 (24) 75 (24) 290 (24)
406 120 (24) 346 140 140 (24) 75 (24) 290 (24)
Universal Beams
102 50 (16) 62 54 - - -
127 62(20) 77 70 - - -
133 57 (20) 83 70 - - -
140 69 (24) 80 70 - - -
146 64 (24) 86 70 - - -
152 73 (24) 92 90 - - -
165 67 (24) 105 90 - - -
171 72 (24) 111 90 - - -
178 72 (24) 118 90 - - -
191 74 (24) 131 90 - - -
210 80 (24) 150 140 - - -
229 80 (24) 169 140 - - -
254 87 (24) 194 140 - - -
267 91(24) 207 140 90(20) 50 (20) 190 (20)
292 92(24) 232 140 100 (24) 60 (24) 220 (24)
305 100 (24) 245 140 120 (24) 60 (24) 240 (24)
419 112(24) 359 140 140 (24) 75 (24) 290 (24)
Steel Section Index


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