16" Deep, 4'-0" Wide Precast Double Tees

[pcronin]

I recently performed a site visit on a project and found 16" deep, 4'-0" wide double tees for a roof structure. I contacted PCI and they informed me that they do not have any load tables for older 16" double tees. I found load tables for both the 14" deep, 4'-0" wide and 16" deep and 6'-0" wide, but I can't find them for the member size I need. A cantilever portion of the tee was removed and the tee has (8) 7-wire strands and we believe them to be draped. If anyone knows where I can find the correct load tables for these members let me know. This will help verify their capacity. I am currently performing hand calcs for the members but it requires me to make a lot of assumptions regarding the prestressing. I found a similar project, which specifies the same size double tees dated 1971 but I only have the contract drawings and not the shop drawings so I know this is not the only building with these members. The project in located in New Jersey.

 

[pcronin]

Thanks for your help but I have tracked down the manufacturer and they have already forwarded me the old load tables. Thanks again.

 

[dik]

If you have a fax number or eMail address... I'll send you a copy of 2400x400 DT (Normal Density Conc) from the CPCI. They have strand patterns, 2-6 Straight and 6-10 Depressed for spans from 5 to 18 metres

 

[dik]

4' or 8' wide with stems at 4' o/c? If the latter I can fax or email you some design tables.

 

[pcronin]

Thanks for your help but they are an unique size. They are only 4'-0" wide with ribs at 24" o.c. Furthermore, the flange of the tee is only 1.5" thick. I found the local manufacturer who used to supply this unique size and determined the capacity from their charts.

 

[WDM]

I am inspecting an old road bridge made from (6) 36" wide double tees. The double tees are 19" overall depth, 5" flange thickness, webs at 24" on center, with (2) 0.5" strands in the bottom of the webs. The bridge was abandoned and moved to a residence for crossing a small stream. The original span has been halved by adding a steel support beam at mid-span. The local fire department has asked for a letter from a structural engineer stating the bridge is safe for a fire truck to cross. This is a very infrequent load, hopefully.

Does anyone know where I can get load tables for this old section?

I plan to use H20 loading.

Thanks in advance.

 

[ishvaaag]

WDM

My main concern regarding your question is what seems to be the use of a precast beam as a continuous one of half the span. This might bring (or not) problems depending on how the thing is and as been truly built. Has the original beam been severed in two parts?

 

[RiBeneke]

You should determine, if possible, what reinforcing steel and (presumably) prestressing strand has been used in the beam. You may be able to obtain some information by using a rebar covermeter, may also need to expose the rebar in some areas and close up with epoxy. It is important to establish whether the prestressing strand profile is straight, draped or deflected. Then do the necessary calcs. I do not think the use of load tables is appropriate or safe here.

 

[Sherard]

I have come across these 16" x 4' Double Tees just recently. Where were you able to get the load tables for these from? Thanks for your help.

 

[pcronin]

For the specific precast tees I had on my project, I obtained the load tables from Nitterhouse Concrete Products in Chambersburg, PA. They are one of the ooriginal precast companies in this area and had old load tables for the specific section I needed. You do need to field verify the shape (straight or draped), number and size of the tendons to make sure you have the correct properties. If you provide me with your fax number, I can send over the chart I was given.

 

[Sherard]

My fax number is (905) 682 5896. As you say, I'll need to know the actual size and number of tendons, but the tables would give me a place to start. Thanks for your help.