How can you find concrete beam depth if you have length which is 6m?

Hi,

Depth of beam depends on serviceability and ultimate state design requirements. 

You should satisfy the ultimate design strength conditions when calculating the beam's capacity and therefore reinforcement.  Also, you should respect the serviceability requirements represented as deflection limits. 

In aci table9.5 (a), the aci puts the minimum section elements that should used to have an adequate deflection values. 

Of course this table shows that the minimum values depend on the end conditions of the beam whether it is simply supported or continuous. 

Therefore,  for example if a beam is simply supported,  the minimum beam thickness equals to dpan/16 =6/16 =0.375 m say0.4m.

Thus, check the table to know exactly your beam conditions and consequently know what thickness to be used.

Regards

Yes , When I have spare time , but during 20 years work i haven,t it.   

Thank You Mohammad great answer.