Web Side Plate Connection

Type of connection: Web side plate connection

Unit system: Metric

Designed acc. to: AS 4100

Investigated: Bolts, base metal, welds

Plate material: Grade 300

Bolts: M20 Grade 8.8

Welds: fillet welds with the size of 8 mm and strength 490 MPa

Example taken from: B. Kirke, I.H. Al-Jamel. Steel Structures: Design Manual To AS 4100, 2004 – Chapter 9.4.1.3

Geometry

Beam UB 406×178×60 is connected to column UC 254×254×89 by a web side plate with dimensions 280×90 mm. Four bolts M20 grade 8.8 are used with the pitch of 70 mm. It is assumed that the beam cannot rotate and be loaded by the bending moment around the weaker axis because of the spreader beams and floors.

Applied load

The beam is loaded by shear force. To be conservative, for the design of bolts, the shear force should be at the position of the column face so that the group of bolts is loaded also by bending moment – select forces in position 130 mm. For the design of fin plate and welds, the shear force should be applied at the position of centre of gravity of the bolts at the beam web – select forces in bolts.

Results of manual calculation

The results of B. Kirke, I.H. Al-Jamel. Steel Structures: Design Manual To AS 4100, 2004 – Chapter 9.4.1.3 are used as manual calculation. The maximum shear force acting on bolt is 85.9 kN. This value is close to the shear resistance of the bolt – 92.6 kN. The resistances of the plate – design bearing and tearing capacity is almost twice higher. The shear resistance of the web plate is 322.6 kN which is close to the applied load. The fillet welds are the size of 8 mm and grade 490 MPa; the resistance is \( \phi V_w = \phi \cdot 0.6 \cdot 490 \cdot \frac{8}{\sqrt{2}} = 1.33\, \textrm{kN/mm} \), the force per vertical unit length is 0.84 kN/mm so the reserve is 37 %. The weakest link are the bolts. With the assumption of linear force distribution in bolts, the maximum applied force can be 270 kN.

Results of IDEA StatiCa

The decisive load position for this connection is at the column face. The group of bolts is loaded by the shear force and bending moment. At the shearload of 270 kN, the most stressed bolt is loaded by shear force, V*f = 92.1 kN, and small tensile force, N*f = 13.5 kN, due to the deformation of the one-sided fin plate. At this load 270 kN, the most stressed bolt is utilized at 99.9 % and the connection reached its maximum resistance. This position of shear force is also decisive for the resistance of fin plate steel; the strain 5% is reached at the load of 305 kN.

The shear load position at the position of bolts is decisive for design of welds. The resistance of fin plate is smaller then for welds and fails at the applied shear load of 335 kN. The plastic strain of the fin plate is shown on the deformed shape in the figure below.

For connections loaded by extreme shear force, it is important to carefully choose the position of the shear load because various elements are also loaded by significant bending moments caused by this shear force on a lever arm.

Comparison

The shear resistance of the web side plate connection was determined as 270 kN both in manual calculation and in IDEA StatiCa due to the shear resistance of bolts. Both manual and software assessment showed identical resistance and failure mode.

Sample files

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