--- title: "Bolted bracket on ISHB 300, 600 kN, M24" subject: "Design of Steel and Timber Structure" chapter: 4 key: "semester_6/design_of_steel_and_timber_structure:bracket-ishb300-m24-600kn" source: https://www.bctengineer.com/q/semester_6/design_of_steel_and_timber_structure/bracket-ishb300-m24-600kn site: BCT Engineering --- # Bolted bracket on ISHB 300, 600 kN, M24 Design of Steel and Timber Structure · Chapter 4: Connections in Steel Structures - Asked in: 2072 Magh, 12 marks - Video: [Numerical on Bracket Connection Type II - Design of Connections](https://www.youtube.com/watch?v=8N3uFPHMW2A) — Ekeeda - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/design_of_steel_and_timber_structure/bracket-ishb300-m24-600kn - Whole chapter: https://www.bctengineer.com/md/semester_6/design_of_steel_and_timber_structure/chapter-4 ## Question Design a suitable bolted bracket connections of a 12 mm thick bracket plate to the flange of a ISHB 300 @ 577 N/m to carry a vertical factored load of 600 kN at an eccentricity of 300 mm from face of column. Consider the eccentric load not lying in the plane of bolted joints. Use M24 of grade 4.6. ## Short answer Use 16 M24 grade 4.6 bolts in two vertical lines of 8, pitch 80 mm, gauge 100 mm. The joint is safe under combined shear and tension; provide a stiffener or thicker plate against prying. ## Answer **Given:** factored $P=600$ kN at $e=300$ mm from the column face; the load is **not in the plane of the bolts**, so each bolt carries direct shear and tension from the moment. ISHB 300 @ 577 N/m: $b_f=250$ mm, $t_f=10.6$ mm. Bracket plate 12 mm; M24 bolts, grade 4.6, $d_0=26$ mm; E250. #### Bolt capacities (IS 800:2007 cl. 10.3) - M24: $A_{sb}=452$, $A_{nb}=353$ mm² - Shear: $V_{dsb}=\dfrac{400}{\sqrt3}\times\dfrac{353}{1.25}\times10^{-3}=65.22$ kN - Tension: $T_{db}=\dfrac{\min(0.9f_{ub}A_{nb},\ f_{yb}A_{sb}\gamma_{mb}/\gamma_{m0})}{\gamma_{mb}}=98.62$ kN - Bearing on the flange (10.6 mm, $e=40,\ p=80$): $k_b=0.513$, $V_{dpb}=107.0$ kN (not governing) #### Layout Two vertical lines of 8 bolts (16 bolts), gauge 100 mm (flange 250 mm), pitch 80 mm, end distance 40 mm ($\ge1.5d_0=39$ mm), bracket depth $=40+7\times80+40=640$ mm. The bottom bolt row is taken as the axis of rotation (conservative). ```text | o o y=560 | o o y=480 600kN | o o ... ------>| o o y=80 300 | o o y=0 (axis) ``` #### Forces - Shear per bolt $V=\dfrac{600}{16}=37.5$ kN - $M=600\times300=180\times10^3$ kN·mm; $\Sigma y^2=2\sum y_i^2=1792000$ mm² - Maximum tension (top row): $T=\dfrac{My_{max}}{\Sigma y^2}=\dfrac{180000\times560}{1792000}=56.25$ kN #### Interaction (cl. 10.3.6) $$ \left(\frac{V}{V_{db}}\right)^2+\left(\frac{T}{T_{db}}\right)^2=\left(\frac{37.5}{65.22}\right)^2+\left(\frac{56.25}{98.62}\right)^2=0.656\le1.0 $$ Also $V