Product(s):	SACS
Version(s):	23.0
Area:	Fatigue

Problem

How SACS defines inspection points for SCF calculation?

Solution

The points are defined by taking a section on the brace.

Please refer figure 1 of SACS fatigue manual which designate the eight points along with their tags (like T, B, TR etc) for a tubular connection. In member fatigue report, these tags are referred as locations of fatigue damage.

Figure 2 provides same information for other sections.

Let me try to explain the scenario with the following sketch.

Member 1-3 (with an intermediate joint #2) is the chord and member 2-4 is the brace.

Here, the common joint is #2. The plane for reference chord will contain all the 4 joints.

Now, let us consider 3 scenarios.

Case 1: Member 1-2 and 2-3 both have same thickness. Here, the reference chord member is 2-3 as this one forms an acute angle with the brace.

Case 2: Member 1-2 has higher wall thickness than that of member 2-3. Then Member 2-3 is the reference chord member.

Case 3: Member 1-2 has lesser wall thickness than that of member 2-3. Then Member 1-2 is the reference chord member.

Now, when the reference chord member is identified, then as mentioned in the manual, imagine someone standing on the reference chord and looking through the brace towards the common joint# 2 will guide the positions. You can refer the Section A-A mark up in Figure 1 of SACS fatigue manual.

So, for the case 1 and 2 mentioned above, when seen through the brace towards joint #2, standing on member 2-3, the TOP position shall be left side of #2, towards #1.

For case 3, it will be right side of #2, towards #3.