specifying J anchorage bars grade 8.8 2

[jor1492]

Hi all,

I want to sent to fabricate J anchorage bars for a tower crane foundation.
As per the vendor of the crane the anchorage bars need to be grade 8.8, so my question is: to specify the material for the manufacture, it is enough information for the manufacturer, only specifing him " Carbon steel grade 8.8" or what is the normal material specification to achieve a grade 8.8.

thanks in advance.

 

[klaus.]

well grade 8.8 is not really an official material specification
depending on where in the world you are people dont know what 8.8 means
it would be safer to specify more clearly....

 

[JStephen]

In the newer ACI anchorage requirements, the embedment strength of headed anchor bolts will generally be higher than for J-bolts, so confirm the adequacy there as well.

 

[jor1492]

as the spec sheet by the vendor is in french I could not notice about this information.
After a translation the material spec is XC48 (French spec), this is SAE 1045(American spec) and to achieve the grade, the bolts require to be tempered and quenched.

Thanks all by your answers.

 

[dik]

and don't use J bars, use heavy hex head on threaded rods.

Dik

 

[robyengIT]

8.8 is normaly used for bolts class. It means :
"8" : min ultimate stress (tension) = 800 N/mm2
".8" : min yield stress (80% of the ultimate stress) = 640 N/mm2

I don't believe the XC48 can achieve the same strength

 

[Tmoose]

"After a translation the material spec is XC48 (French spec), this is SAE 1045(American spec)"

Is grade 8.8 still in a vendor's spec somewhere ?

 

[dik]

8.8 is normaly used for bolts class.

Is it available in bar stock so it can be threaded?

Dik

 

[robyengIT]

As far as I know it is available in bar stock for bigger diameters or in coils for diam till 16 mm. Threading is done by pressure deformation (rolling and pressing at high temperature. I don't know the technical word for that procedure) and not by a lathe

 

[dik]

Roby: Thanks...

Dik

 

[robyengIT]

the process is called "thread rolling" and it is performed by forging at ambient temperature. Sorry for mistake (in the same production line the hexagonal head is realized at high temperature)

 

[BJI]

Most 8.8 bolts are basically a chrome moly 4140, if you need the increased strength. However, for anchor bolt you probably won't be able to utilise the full strength, which is why most anchor bolts are only class 4.6 or 5.8. The last french manufactured tower crane I came across required a cast in frame, and the tower bolted to this.