Steel Plate Design

[struggle67]

Hi everyone I'm a fresh graduate in civil engineering and now I'm doing a steel plate design which is 400mm wide, 35mm thick and it's simply supported.The span length is .25m.It's in flexural condition. It look like elementary but I don't know how to consider the width thickness ratio of the plate.If someone knows about steel plate design plz help me thz

 

[rowingengineer]

Normally for these type of applications higher grade steel is used like 800mpa, is this the case with your project

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[BAretired]

That may be correct rowingengineer. It would be nice if the OP would clear the matter up for us. He asks a question, then abandons the thread leaving us all wondering.

Why would it be normal to use 800MPa for this application rather than a thicker plate of a more commonly available grade of steel?

BA

 

[PEinc]

Because the anchor's wedge plate is relatively thick and stiff, the anchor's load to a simply-supported bearing plate is not really a distributed load. The stiffness of the wedge plate causes the anchor load to be applied to the bearing plate closer to the ends of the plate's span. This reduces the plate bending. I would expect a bearing plate for a 5-strand tieback anchor, spanning 250mm to be about 60 - 75 mm thick with Fy = 36 to 50 ksi. The larger the diameter of the wedge plate, the less load is applied to the middle of the bearing plate. The attached picture is from a recent tieback anchor project. The bearing plates spanned approximately 1'-5". The tieback design loads were generally in the 200 to 400 kip range. The steel for the bearing plates had Fy = 50 ksi. The plate thickness for a 5-strand, 176 kip DL anchor was 2.75 inches. If you ask the tendon supplier, they will often give you the plate design for the particular anchor design load and span.

www.PeirceEngineering.com

 

[BAretired]

From the description given by the OP, I assumed there were five strands equally spaced along the 400mm length, presumably at 100mm oc and centered on the 250mm span. On that basis, it seemed reasonable to take the moment as PL/4 where P is 144*5 = 720kN and M = 45kN-m. If that is not correct, my earlier comment is not valid.

BA

 

[rowingengineer]

we found that if the plate strength was well below the equipment strength, reuse of the plates is limited, thus we increased the strength. possibly a fagtiue issue as well, but mostly reuse condition.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[struggle67]

I used 460 MPa.I tried as PEinc said with M=PL/4.I got the thickness around 70mm

.I also find out in practice they use that much thickness.Thank you all for your answers.It help me a lot.

 

[BAretired]

?

BA

 

[struggle67]

Sorry I tried like BAretied said.Should I assume them as impact loads?

 

[BAretired]

They are not impact loads. Stress is applied gradually. I don't know how you came up with 70mm using Fy = 460 MPa. I believe I came up with 50mm using 300 MPa but I may be misinterpreting the problem.

Why don't you provide a sketch and your calculation?

BA

 

[dik]

for a plate that small and supported on 4 sides, I wouldn't likely use PL/4, unless for a quick check... also, if I had a plate of a given thickness and was trying to use it, I'd look at the load distribution on the plate... unless a hard wheeled load, it may be that a UDL is applicable.

Dik

 

[struggle67]

I got 70 mm because I used impact factor for safety.its supported on two sides only dik.I realized that allowable strength is a lot more than require but I went to a precast site.In practice they use 75 mm thickness for same plate in the conditions as mine.And I have no idea why they use that much thickness.

 

[PEinc]

It is not unusual to design these bearing plates for 95% of the 270 KSI guaranteed ultimate strength (GUTS) of the tendons. Check the recommendations of the Post-Tensioning Institute (PTI).

http://www.PeirceEngineering.com

 

[dik]

Not a wheel load, but PT anchors... sorry

Dik