Calculations of a welded joint consisting of a fillet and bevel groove 1

[engbob826]

We manufacture towers posts with round base plates (made from T1) welded to the ends. The posts are 4" in diameter solid shaft at 55ksi and beveled at 45 degrees making a 1"X1" bevel. The posts are then welded filling the bevel followed by a 11/16" fillet. The posts are capable of taking a tensile load of 473kips. I'm tring to determine what weld wire to use such as E80 or E70. I'm having trouble determining what would be the correct shear area of this joint I should use to determine which weld wire to use. Using E70, the 11/16 fillet weld alone gives me a strength of approximately 150 kips. But I'm unsure as to how much additional strength I get from the chamfer. Any help would be greatly appreciated.
Thanks

 

[metengr]

Since the bevel you describe is considered a partial penetration groove weld, you can take credit for the added load carrying capacity of this as a groove weld in addition to that of the fillet weld.

 

[rjenson]

review bloggett's welding design handbook from lincoln. the handbook has been around for a long time and has invaluable inforamtion in the design of weldments.

 

[engbob826]

Metengr & rjenson,
So if the fillet only is worth 172 kips at E70, and the chamfers leg is approximatly .9" which gives 184kips. Would my total load capability be 172+184=356kips? I was thinking the worst shear area is the hypotenuse of the chamfer which is appoximatly 1.375" would then give 280kips using E70 wire.
I've looked through blodgett, but did not see anything that looked like the example I have.

Thanks
Robert

 

[metengr]

Actually, Blogett's book does have a section on determining weld size, which can be used to determine allowable loads. Remember, for fillet welds you need to assign a strength reduction factor of .49 if you are using the tensile strength of the weld metal (in this case 70 Ksi). For welds in tension, the strength reduction factor should be 0.74.

Regarding your combined load carrying capacity, they are not directly additive. In this case you need to take the square root of the sum the squares of the forces at 90 degree angles - the shear load across the effective throat of the partial penetration weld and the shear load across the external fillet.