No, you are wrong

forces on elevator
Wx+T=Wp (1)
Force on P of Beam, P is a fixed point of the rope on the beam

Tcos45=2/5Wx+Wb/2 (2)

From (1) and (2), eleminate Wx

Tcos45=2/5(Wp-T)+Wb/2
Therefore:
T=(2/5Wp-Wb/2)/(2/5+cos45)