Composite Steel-I Type Section with unsymmetrical deck widths on either side of web


Is it possible to define an unsymmetrical composite Steel-I beam composite section where the deck width on one side of the beam web is different from the deck with on the other side? It is often the case for exterior beams where the overhang width is not necessarily equal to half of interior bay width?

We can define the unsymmetrical deck using Composite-Steel - I type-II.
Input the value of Sg, Top and bottom accordingly to define the unsymmetrical deck as shown below.
Let's our slab is 2x0.25 m  and 0.85m on one side and 1.15m on other side. Keep Sa =0.
Now half top flange width is 0.3 m, so Top = 0.85-0.3 =0.55m. Similarly for bottom.


Using Composite Steel I (Type II) section for unsymmetrical deck also changes to centroid of the section. As the program seems to model the beam at the centroid of the section, the beam geometry would need to be redefined based on the shift in the centroid from the centerline of the steel beam.

In the attached screen capture, the end sections of the beam at the top were redefined using Type II composite steel I section. Notice the shift in the location of the steel beam.


Yes, model is using the centroid of composite section as section offset selected is centre-centre. 
If we want to define the beam using centroid of the steel section, then we can use the section offset option.

Here, I used the left-top as reference offset.  Now, from that I further provided the horizontal offset from "extreme fibre" of required value.
Here, in this case, as the web centroid is located at (0.7+0.35) m = 1.05 m away from the extreme left top position so horizontal offset value was given 1.05 m.
where 0.7m is top flange distance from the deck leftmost point and 0.35m is half the flange width.
Creation date: 6/4/2021 3:43 PM      Updated: 6/4/2021 3:43 PM
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