Splice plate for ISHB 350 column

Data: ISHB 350 @ 72.4 kg/m ($h=350$, $b_f=250$, $t_f=11.6$, $t_w=10.1$ mm, $A=9221$ mm²), factored axial load $1000$ kN at the splice, ends machined for bearing. M20 bolts grade 4.6 ($d_0=22$ mm); E250.

Design basis

Because the column ends are machined and in full contact, most of the load passes by direct bearing. The splice plates and bolts are designed to carry at least 50 % of the factored load ($P_s$) and to hold the two lengths in line (against bending from accidental eccentricity and erection loads).

$$P_s=0.5\times1000=500\ \text{kN}$$

The load is shared in proportion to area: flanges $A_f=2\times250\times11.6=5800$ mm², web $A_w=(350-2\times11.6)\times10.1=3301$ mm².

• Flanges: $P_f=P_s\dfrac{A_f}{A}=314.5$ kN → 157.2 kN per flange
• Web: $P_w=P_s\dfrac{A_w}{A}=179.0$ kN

Bolt values (M20, 4.6)

• Single shear: $V_{dsb}=\dfrac{400}{\sqrt3}\times\dfrac{245}{1.25}\times10^{-3}=45.26$ kN; double shear (threads conservatively in both shear planes): $2\times45.26=90.5$ kN
• Bearing ($e=40$, $p=60$): $k_b=0.606$; on flange 11.6 mm $=115.3$ kN, on web 10.1 mm $=100.4$ kN
• Flange bolt value $45.26$ kN (single shear, outer splice plate); web bolt value $90.5$ kN (double shear, two web plates).

Flange splice

$n=\dfrac{157.2}{45.26}=3.5$ → 4 bolts on each side of the joint per flange (2 rows of 2, pitch 60, gauge 120, end 40 mm). Flange splice plate $250\times10$ mm, length $=2\times(40+60+40)+$ gap $\approx300$ mm. Stress in the plate $=\dfrac{157.2\times10^3}{250\times10}=62.9$ N/mm² $<f_y/\gamma_{m0}=227$ N/mm² ✓

Web splice

$n=\dfrac{179.0}{90.5}=1.98$ → 2 bolts per side in double shear ($2\times90.5=181$ kN $>179$ kN ✓); web plates (two, one on each face) $200\times8$ mm, 250 mm long, with 2 rows of bolts.

Notes

• The splice is at 3 m height, so bending from lateral loads is small; the plates and bolts also hold the two lengths in line and resist erection loads.
• Packing plates are provided if the two lengths differ in size.

Answer: flange splice plates 250 × 10 mm with 4 M20 bolts each side per flange; web splice plates 2 × (200 × 8 mm) with 2 M20 bolts each side.