Deflection in BS8110
Deflection in BS8110
(OP)
In BS 8110 there is a modification factor "kt" (table 3-10) ,which multiplied into basic span/depth factor
this factor take the tension steel effect in deflection.
in many calculation this factor become less than 1 !!( .75, .6 etc)
then the S/d factor reduced !
is this factor used for enhancing the span/depth?
it's not giving any sense if this factor less than 1.
does any body agree with me ?
AhmedR
this factor take the tension steel effect in deflection.
in many calculation this factor become less than 1 !!( .75, .6 etc)
then the S/d factor reduced !
is this factor used for enhancing the span/depth?
it's not giving any sense if this factor less than 1.
does any body agree with me ?
AhmedR






RE: Deflection in BS8110
By the way, my 1997 edition doesn't use the notation 'kt', what edition is your's AhmedR?
John
RE: Deflection in BS8110
thanx for ur response .
I know about the other factor "kc" which already more than 1 as the code equ.
u r right its come when M/bd^2 is large (K also be grater than .156),but some times i make max. value of kc (1.5) and final s/d become less than basic too.!!
i think this factors must not taked if k>.156
or beter to calculate actual deflection as part 2 or ACI methode.
Iam using the 2002 copy for BS8110:1997 with Amend. 1&2.
but using kt & kc notations from my books and IStructE documents .
Best regards.
Ahmed
RE: Deflection in BS8110
I'm no expert but this is my interpretation;
The K factor is used to determine the necessity for compression rebar, for flexural strength purposes. It has no effect on determining the S/d ratio. More rigorous methods such as in part 2 should give more accurate results.
The issue of the final S/d ratio being less than the basic is just a matter of calibration. The code committee could have chosen (min.kt x max.kc) = 1 , with the basic ratios in Table 3.9 reduced to suit.