Simply supported beam vs simply supported flange beam

Homework Statement

I want to design the beam as circled . I am wondering should I design it as a simply supported rectangular beam or simply supported flange beam
Someone told me that i should design it as simply supported flange beam . i doubt that it's correct .

Homework Equations

The Attempt at a Solution

I think it should be designed as simply supported rectangular beam . Correct me if i am wrong . [/B]

 

[Nidum]

Could you please explain what that diagram is meant to represent ?

 

View attachment 215643

Could you please explain what that diagram is meant to represent ?

there are 3 slabs here , i want to design the circled bottom beam