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[Sunil Kumar Jatav]

Hello sir,
I am working on the design of air concourse of certain railway station. The design length and width of concourse are 90 m and 25 m respectively. The limiting condition of this project is the erection of the concourse due to limitation of space and surrounding. Therefore half portion of concourse will be erected using the crane while the other half by incremental method. The spacing of column width wise is 9m, 8.5m and 7 m and length wise as 31.8m, 20.8 m, 31 and 4.2 m cantilever portion. I want to design Longitudinal Composite girder with metal deck sheet in span of 31.8 m with C/C spacing of 3 m across the 9 m width side. I am designing the composite beam as per IS 11384-2022. I have developed excel sheet based on the IS code which is attached. The main governing criteria for this composite beam are serviceability (Deflection) assuming simply supported girder. The deflection in composite action is coming around 106 mm which result in increasing the beam depth with considerable amount around 1.4 m. Typical Size of I shape girder is (400x40 flange 1400x16 web).
I have the following query regarding this.
1.     Whether the procedure I adopt for design as per Indian code is correct.
2.     I want to minimize the cross section of girder how I can I do that without compromising the serviceability.
3.     Deflection limit as per Is 800 is L/300, is it true for composite beam also.

[vikram.jeet]

Deflection issue :

Pl try to enhance MOI of girder s

Increase flange plate thickness (top and bottom each ) ,, if thick plate not available use 40mm plus other one of lesser Width / thickness at both flanges - most eco way

Or

Use Twin Girders of steel with less plate thicknesses,,

In case Topping is chequered plate,, take advantage of that in MOI
If Topping is RCC, MoI of compodite can be seen

👆few options but at some extra