Expert: Arshad Khan - 12/9/2009

Question
QUESTION: Dear arshad khan,
I have viewed the tutorial of section cuts in etabs.. also have looked in the help files and done a google on that, but still I couldn't grip it...  
what i need to see is moments at a certain section of a slab

1) Is the section cut data report along the section line drawn or on the left and right of section line..??
2) I couldnt get they way forces are reported./. I mean what does 1 mean, 2 and Z ?????
3) All i could understand from CSI tuts and google that the information given by section cut is reported at the center of section cut... I couldnt figer it out what is meant by left and right..????
4) if i want to obtain negative moment at the end of a way one slab shall my section cut pass along the edge of beam supporting slab or perpendicular to the beam supporting slab???

Please advice...
Thanks in advance

ANSWER: Hi Muhammad,

Aplogies for this late answer, but I have not used section cuts much myself and I agree with you that the ETABS documentation is not very detailed. So in the end I raised this question with CSI and their response is as below:

The following rules may be used for planar cuts (i.e., Draw > Draw Section Cut) until we give more user control for this:

1. For cuts in plan (slab results) the default 1 axis is in the direction of the cut and  
      F1 is in-plane shear
      F2 is axial force
      FZ is out-of-plane shear
      M1 is out-of-plane moments
      M2 is twisting moments
      MZ is in-plane moments.

2. For horizontal cuts in elevation of XZ walls (pier results) the default 1 axis is in the X direction and
      F1 is in-plane shear
      F2 is out-of-plane shear
      FZ is axial force
      M1 is out-of-plane moments
      M2 is in-plane moments
      MZ is twisting moments.

3. For horizontal cuts in elevation of YZ walls (pier results) the default 1 axis is 90 degrees to X direction and
      F1 is in-plane shear
      F2 is out-of-plane shear
      FZ is axial force
      M1 is out-of-plane moments
      M2 is in-plane moments
      MZ is twisting moments.

4. For vertical cuts in elevation of XZ walls (spandrel results) the default 1 axis is in the X direction and
      F1 is axial force
      F2 is out-of-plane shear
      FZ is in-plane shear
      M1 is twisting moments
      M2 is in-plane moments
      MZ is out-of-plane moments.

5. For vertical cuts in elevation of YZ walls (spandrel results) the default 1 axis is 90 degrees to X direction and
      F1 is axial force
      F2 is out-of-plane shear
      FZ is in-plane shear
      M1 is twisting moments
      M2 is in-plane moments
      MZ is out-of-plane moments.


---------- FOLLOW-UP ----------

QUESTION: Dear Sir,
Any idea about left and right ???

Best Regards,
Muhammad Umar

Answer
HI Muhammad,

Yes, this part is covered in the help menu, as quoted below. These are left and right sides of the section cut. So if you start the section cut from bottom of your plan to top, left and right sides are as you see them on the screen. If the section cut is from left (Start) to right (End), then left is above and right is below the section cut as you see it on the screen.

QUOTE
"Resultant Force Location and Angle edit boxes. The X, Y, Z values displayed in this area of the form are the coordinates of a point along the section cut. The initial values are the mid-point between the Start Point and End Point. Type revised values in the edit boxes to display forces at another location along the section cut.  The angle value is the angle measured counterclockwise from the positive Global X axis to the positive X axis of the local coordinate system in which the integrated forces are reported. The initial X direction is parallel to the section cut from the Start Point toward the End Point.  Use the check boxes in this area of the form to select the forces to be included in the calculation (that is, the forces associated with floors, beams, braces, columns, walls, ramps). If a check box is unavailable, that element is not included in the model.

Integrated Forces display boxes. The values displayed in these display boxes are the forces and moments along the right and left sides of the section cut at the point/coordinates defined by the coordinates listed in the Resultant Force Location display boxes."
UNQUOTE