Iam designing a concrete slab supported on two beams,the deflection results obtained in staad pro (post procssing) are given in length unit,how do i compare these results with allowable deflection because the alowable deflection according to BS 8110 (Table value 3.9 X Modification factor) which do not have units.
Hi Joseph, with regard to question 1, as long as you satisfy the span/effective depth ratio requirement then deflection is satisfactory.
Yes but when the load is critical sometimes the deflection will occur even if span/effective depth ratio is ok,what is the way forward?
Can you please show an example of where this occurs?
I will attach it,but when you take span/effective depth you will get actual deflection value,and this actual value you have to campare it with allowable maximum deflection value which has to be computed as shown on examples above.So we can't depend on actual deflection value (span/d) we have to compare it with allowable value
The span/effective depth ratios given in Table 3.9 and modified by equation 7 are deemed to satisfy requirements and so as long as this is value is not exceeded then the deflection is deemed to be satisfactory. Alternatively, you can calculate the deflection and compare with span/250 as noted in 220.127.116.11.