LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Sathvika Meenakshisundaram — Thu, 21 Sep 2023 12:34:09 GMT

Hello, I am still having problems with shear in LEAP. I unchecked the "Consider shear reinf. across failure plane (FDOT Alternative)" under Rating Parameters like suggested. After turning this option off and doing a quick hand calculation to verify the shear rating factors, where I pull the shear capacity, dead loads, and live loads reported by LEAP, the calculated shear rating factors are less than LEAP's.

I am wondering if I should be using a different version?

Can someone please look into this? I can send the models and calculation files, if that will help.

Thank you

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Sathvika Meenakshisundaram — Wed, 07 Jun 2023 13:39:47 GMT

Thanks, Alex. I ended up verifying the shear ratings for all the beams because for my case, some needed the extra stirrups and for others the multiple shear zones did not apply. I appreciate you looking into this.

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Alex O [Bentley] — Mon, 05 Jun 2023 18:06:05 GMT

Sathvika, function of POI location and stirrup placement you may miss one stirrup even if the stirrup spacing is constant across failure plane. The method works well if you clearly can intercept more stirrups placed closer than at a given POI.

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Sathvika Meenakshisundaram — Mon, 05 Jun 2023 17:51:27 GMT

Alex, this still does not answer my question below. I understand that conspan does not report these values like I acknowledged already in my response. Regarding the shear capacity, I am hand calculating all the numbers.

"Why does the rating factor in LEAP decrease when this option is checked? There seems to be an issue in conspan regarding this option even when stirrup spaces are consistent across the failure plane."

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Alex O [Bentley] — Mon, 05 Jun 2023 17:40:01 GMT

Sathivika, As I did mention to you in my initial response: "The shear report does not report Av-provided, and shear capacity for this method" We are talking about the FDOT alternative of counting stirrups across failure plane. So you cannot use capacity from shear design report for computing the rating factor when FDOT alternative is selected.

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Sathvika Meenakshisundaram — Mon, 05 Jun 2023 16:57:21 GMT

Looking into this further, it appears that checking the FDOT alternative "Shear rf. across failure plane" does not work as intended. In bullet no. (2) in my previous response, the 1.57 rating factor output by LEAP matches closely with the 1.60 hand-calculated factor. I checked the other two shear rating factors - permit Strength II and design inventory and they all match closely when this option is unchecked. Looks like there is an issue inside of conspan when the FDOT alternative is selected for computations. Please confirm if this is the case or if the difference in shear rating factors is caused by something else.

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Sathvika Meenakshisundaram — Mon, 05 Jun 2023 15:17:06 GMT

Alex,

This bridge is in Florida and I do have the "Shear rf. across failure plane" selected as allowed by the Florida Load Rating Manual. However, at the governing shear location on this bridge, 0.5*dv*cot(theta) does not take it to the next stirrup zone and the stirrup spacing is consistent for the section. So, even with the option selected, Av should not have increased. I have independently verified Vn at a couple different locations and I am matching LEAP's. When calculating the shear rating factor, however, I am not matching LEAP's rating factors. This step should be just plugging in the capacity, DL, and LL into the rating equation but one of the values used by the program seems to be different (likely the Capacity). Hence, my initial question on where the values for rating equation can be extracted in Conspan. Based on your response, I understand that Conspan does not print the values for each of the parameters in the rating equation at the tenth point locations.

Here is a summary of what I get for the shear rating factors:

1. I am using Beta-Theta Tables procedure for shear capacity per which the strain, beta, theta etc. are load factor dependent. i.e., the variables need to be recalculated for a LL factor of 1.35 vs 1.75. For operating, using a LL factor of 1.35 and going through the full beta-theta procedure, I get a shear rating factor of 1.600 while Conspan reports 1.46 at 0.3L. As mentioned earlier, all the hand-calculated parameters matched LEAP's and the disconnect seems to be when calculating the rating factor. Similar case for Design Inventory where the LL factor is 1.75 and I am not matching LEAP's shear rating factor at 0.2L.

2. I unchecked the "Shear rf. across failure plane" under Parameters and I am getting interesting results. The design operating rating factor for shear at 0.3L went up from 1.46 to 1.57. This shouldn't be the case. At a minimum, it should have been the rating factor of 1.46 that LEAP was reporting earlier.

RE: LEAP Superstructure - Nominal Capacity used to Calculate Shear Rating Factors

Alex O [Bentley] — Wed, 31 May 2023 18:57:21 GMT

Sathvika,

Please make sure you are not using the option of considering the shear reinforcement across the failure plane (see first screen shot below). The shear report does not report Av-provided, and shear capacity for this method. Fort the traditional method of computing Av-provided at location, follow hand calculations for Tutorial 6 (see second screen shot below).