Firstly find the volume of concrete in cu.m.Then if it is P.C.C multiply it by 2400 as density of concrete is 2400kg/ cu.m
Now for R.C.C u know the no. Of bars and their lengths. Find cross sectional area of each bar and multiply by length
E.g:- π/4 X d X d X L (d=diameter of bar, L = length of bar)
Now the result is the volume of bar.
Multiply the volume of bar with density of steel i.e 7850kg/cu.m
You get the weight of steel
Do not forget to deduct the volume of bar from the total volume of members.
Then for rest of concrete the density is 2400kg/cu.m
For fiber reinforced concrete find the ratio of reinforcement and concrete and follow the same process for finding weight.
For lightweight concrete, the density is 1600- 1700 kg/cu.m. Find the dimensions and then volume then find weight.