Splice connection for ISHB 250, 900 kN

Data: ISHB 250 @ 536 N/m ($h=250$, $b_f=250$, $t_f=9.7$, $t_w=8.8$ mm, $A=6971$ mm²), factored axial load 900 kN, ends machined for bearing; M16 bolts (grade 4.6, $d_0=18$ mm); E250.

Design basis

With machined ends in contact, the load is mostly transferred by bearing; the splice plates and bolts are designed for 50 % of the factored load, shared by area:

• $P_s=0.5\times900=450$ kN
• Flanges $A_f=2\times250\times9.7=4850$ mm²; web $A_w=(250-2\times9.7)\times8.8=2029$ mm²
• Flange share $P_f=P_s\dfrac{A_f}{A}=313.1$ kN (156.5 kN per flange); web share $P_w=131.0$ kN

Bolt values (M16, 4.6)

• Single shear $V_{dsb}=\dfrac{400}{\sqrt3}\times\dfrac{157}{1.25}\times10^{-3}=29.01$ kN; double shear (threads conservatively in both shear planes) $=2\times29.01=58.0$ kN
• Bearing ($e=35$, $p=50$): $k_b=0.648$; flange 9.7 mm: $82.5$ kN; web 8.8 mm: $74.8$ kN
• Flange bolt value $29.01$ kN; web bolt value $58.0$ kN

Flange splice

$n=\dfrac{156.5}{29.01}=5.4$ → 6 bolts each side per flange (2 rows of 3, pitch 50 mm, gauge 100 mm, end 35 mm). Outer flange plate $250\times10$ mm, about 340 mm long. Plate stress $=\dfrac{156.5\times10^3}{250\times10}=62.6$ N/mm² $<f_y/\gamma_{m0}=227$ N/mm² ✓

Web splice

Two web plates (one on each face), double shear: $n=\dfrac{131.0}{58.0}=2.26$ → 3 bolts each side (one vertical line at 50 mm pitch, $3\times58.0=174$ kN $>131$ kN ✓); web plates $170\times8$ mm, 200 mm long.

Answer: flange plates 250 × 10 mm with 6 M16 bolts each side per flange; two web plates 170 × 8 mm with 3 M16 bolts each side.