RCPier - Response Modification

Erika Meeker — Mon, 02 Mar 2020 20:09:27 GMT

I am using Leap Concrete Version 18.02.02.03 for a multi column pier design that includes seismic forces. I need to apply a response modification factor for the columns and the help guide states that this can be modified in the Seismic Parameters. However, there is no section for response modification factors in the Seismic Parameters tab.

Any ideas on how to update the response modification factor for column seismic design?

Vertical Shear - Factored Axial Nu

Sathvika Meenakshisundaram — Thu, 21 Feb 2019 16:14:02 GMT

How is the Axial Force, Nu calculated in LEAP per AASHTO LRFD 2018 Equation 5.7.3.4.2-4?

I'm load rating an exisitng AASHTO Type II beam per FDOT specifications. The shear inventory rating controls at 0.9L and the rating factor is less than 1.0. The vertical shear is being calculated by beta-theta equation method (AASHTO LRFD 2018 Section 5.7.3.4.2). In LEAP Analysis options, when the vertical shear method is toggled from beta-theta equations to beta-theta table (AASHTO LRFD Appendix B5), the rating went up to 1.2. Note that in the 2018 version of AASHTO, the Simplified Shear method has been removed and is no longer an option in LEAP.

LEAP's calculations for shear by beta-theta equations under Print ----> Vertical/Horizontal Shear does not mention any Axial Force (Nu).

At 0.9L, the ultimate shear and moment values that I independently calculated matches with LEAP's Vu = 119.5 kips and Mcor = 244.7 kip-ft. There's no external axial force applied. Is Nu being calculated for the applied pre-stress in LEAP? If so how exactly is it calculated and why is it not listed in the table above?

The strain value and the corresponding beta I calculated for Nu=0 kips is way different from LEAP. All my other values match, with Nu being the exception.

Also, using the beta and Epsilon(s) value given in LEAP shear results, I back-calculated factored Nu to be 93.625 kips. Not sure where this is coming from.

Here's the tendon info if requried -

7/16"-250ksi

12 total strands - 10 in the bottom flange and 2 at the top flange.

Please let me know if you need any additional information.

Thanks.

Allyson Orr's Activities

RCPier - Response Modification

Vertical Shear - Factored Axial Nu