How to figure out the deflection of an RC transfer beam ?
There still missing data, slab thickness and end fixation of transfer beam
Anyway, assuming that slab thickness is 150 mm and the beam is simply supported at the ends, the deflection could be calculated as follows:
beam gross inertia for (T) section with effective slab width (12 ts + bo) = 2550mm is 0.37 m4
the cracked inertia of the same beam = 0.087 m4
the effective inertia = 0.091 m4
for Fc = 50 N/mm2 , Ec = 3.3 E+6 ton/m2, then (EI) = 3.0 E+5 ton.m2
own weight of beam = 0.75 x 1.6 x 2.5 = 3.0 t/m
total distributed load = 7.8 + 3 = 10.8 t/m
then the deflection = (5wL^4 / 384EI) + (PL^3 / 48EI) = 0.0386 m
So, the theoretical deflection is 39 mm
To considering the creep effect, the sustained load should be known and the also the amount of compression steel, anyway it is about 1.8 to 2.0 times the short term deflection, hence the total long term deflection is about 2.8 to 3.0 x 39mm = 110 to 120 mm
Practically, you have to consider some other factors such as:
1- Construction stages, the transfer beam will carry all the own weight of the 1st floor, then then next floor load will be carried by a combination of transfer beam and the 1st floor , the load of next floor will be carried by the combination of the transfer beam and 1st & 2nd floors and so on. besides that all walls, finishing and live loads will be carried by a combination of the transfer beam and all the floors. So the actual deflection should be less than the calculated.
2- Practically. the monolithic connection is semi-fixed support not simply supported, hence both actual moment and deflection are less than the calculated.
To get more accurate calculations, you have to use FEM model and consider construction stages, cracked sections and creep effect. you may use SAP200 or ETABS
Source :- Google
There still missing data, slab thickness and end fixation of transfer beam
Anyway, assuming that slab thickness is 150 mm and the beam is simply supported at the ends, the deflection could be calculated as follows:
beam gross inertia for (T) section with effective slab width (12 ts + bo) = 2550mm is 0.37 m4
the cracked inertia of the same beam = 0.087 m4
the effective inertia = 0.091 m4
for Fc = 50 N/mm2 , Ec = 3.3 E+6 ton/m2, then (EI) = 3.0 E+5 ton.m2
own weight of beam = 0.75 x 1.6 x 2.5 = 3.0 t/m
total distributed load = 7.8 + 3 = 10.8 t/m
then the deflection = (5wL^4 / 384EI) + (PL^3 / 48EI) = 0.0386 m
So, the theoretical deflection is 39 mm
To considering the creep effect, the sustained load should be known and the also the amount of compression steel, anyway it is about 1.8 to 2.0 times the short term deflection, hence the total long term deflection is about 2.8 to 3.0 x 39mm = 110 to 120 mm
Practically, you have to consider some other factors such as:
1- Construction stages, the transfer beam will carry all the own weight of the 1st floor, then then next floor load will be carried by a combination of transfer beam and the 1st floor , the load of next floor will be carried by the combination of the transfer beam and 1st & 2nd floors and so on. besides that all walls, finishing and live loads will be carried by a combination of the transfer beam and all the floors. So the actual deflection should be less than the calculated.
2- Practically. the monolithic connection is semi-fixed support not simply supported, hence both actual moment and deflection are less than the calculated.
To get more accurate calculations, you have to use FEM model and consider construction stages, cracked sections and creep effect. you may use SAP200 or ETABS