Hi all,
I am modelling and raft and have assigned latitude and longitude design strips to the raft.
After running the software I would like to check the bending moment to design the raft.
However, when I clicked the plot and activated the Section Analysis window to show the bending moment value, it gave me results like this - maximum bending 7710kNm to the strip at the far right.
If I activated the Strip results and showed the maximum bending moment - it was 4410kNm to the same strip.
Can anyone tell me what the differences are between these two results? And the reinforcement that the programme designed, does it based off the strip results or section analysis results?
Thanks!
Are these plots for the same load combination? If so, please send over your file and confirm what layer you are plotting things from.
Hi Seth!
Thanks for getting back to me.
We set up 2 loadings for earthquake and 8 load combinations for earthquake strength design as below.
Strength design has been activated under these 8 load combos and also 1.2G+1.5Q. Other than that, I turned off the strength design under all other load combos.
The moment plots below they are all under strength design
However, the shear are the same under strip and section analysis.
In the design strip properties did you check the box on the General tab that says "Don't reduce M and V due to sign change"? If so, test with that turned off.
Are the load factors and alt envelope factors the same in those load combinations? If not, test with them all alike.
Seth,
We've been undergoing an exercise similar to Janet's and have noticed a similar discrepancy - bending moments reported through strip and section plots seem to be different.
We've gone a step further in looking at this and have also attempted to read integrated bending moments through corresponding moment plots (for a given load combination) and the program reports yet another value which is different to strip and section plots.
As an example - we are looking at bending moments reported for a longitudinal span segment presented in the snip below.
We expect the value of 1700kNm to be critical and to be reflected in the section analysis output - that is not the case, as presented in the snip below:
When go to plot moments about the x-axis and integrate across the width of the span segment we get yet another value for bending moment:
We've done a check of similar sort for reported shear values - these seem to be reported similarly for strip and section analysis plots, however we still get some discrepancy when measured from shear contour plots.
Your suggestion of checking/unchecking the "Don't reduce M and V due to sign change" checkbox does not seem to make any difference within our model.