Hi All,
I am working on a school project that has some athletic fields around the perimeter of the building site, but for the most part is surrounded by housing developments and wooded areas. You can get an idea of the distances/scale from the football field and track shown on the attached...
Thank you ajk1. I did learn about the clay tile forms as well. To me it seems like the "bridging/blocking joists" may have been driven more by the old form work layout based on some of the information and photos I have found. But they do make sense for stability I guess. More recent...
Hello,
I am currently investigating the removal of a bridging joist located at the mid span of the joist. The span is roughly 15 ft. and the joists 5" X 10" spaced 25" on center. Looking at current ACI design for one way joist systems I have not encountered any bridging requirement, and the...
Hi Straub, I have thought about doing so but have received some negative feedback on mixing systems from my coworkers. To me it seems like any added stiffness along that line will help the cause. Thanks for the input!
Hello,
I am designing a single story braced frame building (110' long by 35' wide and 16' tall). Seismic design category B, Risk category III, 120 mph wind speed per ASCE 7-16. Wind loads govern base on the calculated loads.
Before my involvement with the project it was decided to remove the...
Thank you all for your input. Shear strength is the concern, as the joist are adequate in flexure. Unfortunately it is only ONE location where it is deficient in shear (by 15%). To me it does not make sense to have one location strengthened with carbon fiber due to the cost of mobilization...
Hi All,
I have analyzed and existing concrete pan joist roof structure (1958)for snow drift loads that the minimum compressive strength of the concrete specified on the drawings is 3,000 psi. The joists are adequate in flexure, but are about 15% overstressed in shear. I have already taken...
Hello,
There are some conflicting opinions/approaches to designing elevator hoist beams with my co-workers. I have read some that implement a factor of safety by doubling the required beam rating, and following either LRFD or ASD design which results in a FOS of 3+. I have read that some...
Hi All,
I have a scenario where a contractor is proposing to utilize tie-off anchors that attached directly to the metal roof deck using several self tapping screws (approx. 25 locations). Per OSHA, the tie off design load is 5,000 lbs. and shall have a factor of safety of 2. My concerns are...
Thank you Lomarandil, I appreciate all of your input. Good point regarding exceeding the HS-20 loading, as that was a big concern. Luckily we have ruled out emergency vehicles, as their access would be from ground level. I will take a look at the AASHTO table you provided for the effective...
Please forgive me, I do not have a lot of experience with AASHTO...
I have a project that involves an exterior elevated driveway over the first story of a building (HS-20 loading). The driveway consists of a radiant heated concrete deck (7-9" depth) on top of high density rigid insulation (4"...
Thanks all for the input. I do not have any information of the type of Alloy/temper of the mullions. I am going to have to use a super conservative strength of the alloy. Just to give you an idea of the loads, I am trying to support about 3,100 lbs. at each vertical mullion, so its not...
I am currently working on a project where we are removing a portion of a curtain wall system from the first floor up to the third floor, and re-supporting on the third floor (bldg is 4 stories total - Concrete floor plate construction). The curtain wall gravity loads are currently carried by...
I am trying to determine if utilizing the 70% or 0.7 x 0.6W = 0.42 applies when I am designing a category IV building with an ultimate design wind speed of 125 mph. That corresponds to an MRI of 3,000. So in order to determine the wind service loads from the 10 year MRI or 25 year MRI from the...
Thanks phamENG. It is a hospital and we are currently just checking the deflections utilizing 70% of the service load. Which is a 0.42 factor for the ultimate design wind pressure. We are holding it to a more conservative drift limit of H/500, although the façade could handle H/400. I am...
I am trying to determine if utilizing the 70% or 0.7 x 0.6W = 0.42 applies when I am designing a category IV building with an ultimate design wind speed of 125 mph. That corresponds to an MRI of 3,000. So in order to determine the wind service loads from the 10 year MRI or 25 year MRI from the...
