Print...

Midas Tendon Stress (f_pe)

Question:

Dear Midas Team,

I have done a pre stressed bridge model and I have ran the calculation. I have found the Tendon Stress (f_pe) to be much lower than the Tendon Stress Limit At Service. What could be the reson for this?

I have applied the pre stressing force of 0.7*fy.
I have also checked the tendon losses at the final construction stage and it is not that large.

What may be the reason that the Tendon Stresses are much lower than the Tendon Stress Limit.

Answer:

Hello,

I reviewed the model. This is happening because girder elements and deck elements are activated at age of zero.

Kindly update the activation age of the girder and moreover even for deck as shown below. Update the values for all the composite girder groups.

Further, I would like to suggest that dummy beams for transverse deck element should be given dummy deck material (with C32/40 stiffness and weight density as 0) instead of C32/40 and C32/40 material should be provided to deck as shown above. If this is not done, the deck self weight is accounted twice and self weight results obtained will be not correct.

After updating these value, results for tendon stresses for stitching stage is shown below.

A model file has been attached for further review.

age composite section for construction stage dummy beam midas civil stress tendon

Creation date: 5/31/2021 5:18 PM Updated: 5/31/2021 5:18 PM

Files		Sort by Name Sort by Date
	DataImage53.png 88 KB
	DataImage72.png 17 KB
	DataImage83.png 181 KB
	DataImage91.png 98 KB
	DataImage96.png 34 KB
	HDB type 1 r8.mcb 8 MB
	HDB type 1 r8.mcb 8 MB