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Strength of weld as strong as parent material?
2

Strength of weld as strong as parent material?

Strength of weld as strong as parent material?

(OP)


If I use a 1/4" fillet weld all around on a 4x4x1/4" thick angle to connect to a base plate, is it safe to say the weld is as strong as the angle? Since the area of the weld will be equal to the angle. The angle will have an eccentric load so there will be bending stress. The section modulus should be bigger at the weld right?

RE: Strength of weld as strong as parent material?

If you select the correct filler the welds will be equal to or stronger than the base metal.
Weld fill and penetration are important.
In this case the angle will take a lot more bending load than the flat plate.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Strength of weld as strong as parent material?

Ah yes, but what are the properties of the base metal after welding? Are the mechanical the same after welding as in the original base metal?

Some metals, such as heat treatable aluminum alloys, can experience a degradation in the mechanical properties after welding.

Best regards - Al

RE: Strength of weld as strong as parent material?

It depends......................

RE: Strength of weld as strong as parent material?

Most of us would have assumed the OP was talking about structural steel, in which case Ed's answer is correct. But gtaw's point is well taken.

RE: Strength of weld as strong as parent material?

(OP)
Thanks for the input!

All metal is A36 steel and welding using E70XX electrodes.

The angle cantilevers out for a 5 feet and will take about 200 lb ultimate load (osha temporary guardrail). So there will be a bending moment on the weld/base plate connection.

For bolts I was thinking two 5/8 expansion bolts into solid concrete, spaced about 5" apart.

I didn't think too much about the base plate. I was focused on the angle, weld and anchor bolts. I was having a hard time checking the weld because of the L shape and finding similar example problem which is why I made this tread. My thinking was since both faces of angle is welded the area of weld should be as big or bigger than angle,and then if weld allowable stress was same or better than the angle, I wouldn't have to run the calcs on the angle.

RE: Strength of weld as strong as parent material?

Actually, a double fillet weld, deposited with 70 ksi filler metal, with legs equal to 3/4 the thickness of the base metal will match the allowable stress in the base metal in both shear and tension

Best regards - Al

RE: Strength of weld as strong as parent material?

Hi Bushmill

firstly fillet welds fail in shear So the allowable stress on the joint will be around say 70% of the allowable tensile stress of the component, in addition its likely you will have unsymmetrical bending which means the neutral axis is at some abituary angle depending on how and where the load is applied. This means you need to calculate the angle that the neutral axis is running at in order for you to establish compressive and tensile stresses with a reasonable idea at which point the stresses switch from compression to tension

ā€œDo not worry about your problems with mathematics, I assure you mine are far greater.ā€ Albert Einstein

RE: Strength of weld as strong as parent material?

You need to take a step back and think really carefully about this.

By your questions, and the elementary way you have phrased them, I want to YOU to challenge YOURSELF about your training and qualifications to design this baseplate and post.


It's a temporary handrail mount on an OSHA-regulated site. That means by definition is is man-rated, life-safety items ... even if it's "only" a temporary handrail post. Guard rails are 42 inches high (not 60!), and must be rated for at minimum 50 lbf sideways at 42 inch lever arm moment arm. Minimum. Now, usually, there is a vertical post every four feet, which is where I suspect your 200 lbf sideways came from. What is the direction of the sideways force on the eccentric angle iron? Why the 60 inch requirement? What happens when two 250 lb millwrights stand on the temporary handrail to reach something?

What is your safety factor, and where is this handrail/guardrail actually going to be installed. (Not by itself certainly!) what is the baseplate mounted to, how close to the edge of the concrete pad (???) is the baseplate, what strength concrete (???), what depth and what cure time? If wood, what is the wood fastened to and how?

Why do you assume two anchor bolts are sufficient for an eccentric load on a baseplate that thin and that small? What sizes holes in the baseplate and how far from the edge are the holes?

Do you have room for bolts and washers?

Your weld "design" seems based on assuming equal area is required between angle iron, weld thickness, and baseplate thickness. That is an approximation valid in some circumstances, but why use it here?

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