Shear Flow Weld Design for Flange Plates
Fillet welds between elements in welded profiles such as wide flanges, tees, and other structural shapes, play a crucial role in transferring shear forces and maintaining structural integrity. In this blog post, we’ll focus specifically on shear flow design for throat welds in welded profiles per AISC 360, covering how shear is transferred, weld demands are calculated, and capacities are verified.
Understanding Shear Flow in Flange Plate Welds
When a flange plate is welded along the bottom flange of a wide flange beam, shear forces must be transferred through the fillet welds. These forces typically arise from shear in the profile, requiring the welds to be designed to resist shear flow along the weld length.
Shear flow in these welds depends on:
The applied shear force
The geometry and size of the flange plate and profile
The weld length and size
Proper weld design ensures that the connection can safely transfer shear without exceeding allowable stress limits.
Demand Calculations
The shear flow demand can be expressed as:
Where:
V = Shear force
Q = First moment of area about the neutral axis
I = Moment of inertia of the section
Weld Capacity
The strength of the welds depends on the weld size (throat thickness) and the electrode strength. The nominal shear strength of a throat weld is given by:
Where:
Φ_w = Weld Resistance Factor
F_nw = Nominal Stress of Weld (based on electrode used)
A_we = Effective Weld Area
Example Problem
(Solutions Provided Using CalcBook) Problem Statement:
Demand Calculation:
Geometric Properties:
Weld Stress:
Capacity of 3/16" Welds
Controlling DCR
Conclusion
Flange plate welds are critical for transferring shear forces and ensuring the structural performance of steel reinforcing elements. Using AISC 360 guidelines, engineers can design safe and efficient welds, and with tools like CalcBook, these calculations become faster and more transparent.
Stay tuned for more insights and examples in structural engineering design with CalcBook!
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