shear flow - two RC elements tied together

[oneintheeye]

how do you determine the shear flow in order to determine the fixing requirements if connecting two reinforced concrete elements together in order that they act compositly?

 

[kslee1000]

f=VQ/I, check is the same as for composite steel at interface. Or you are looking for something else?

 

[DaveAtkins]

kslee1000 is correct, but also check the ACI Code. There is a section on horizontal shear flow--I think it is in the composite construction chapter.

DaveAtkins

 

[miecz]

herewegothen-

What code are you designing to? Is one of your elements precast?

 

[Jeff2009]

Assume the depth of each of your beam is H and length is L.

1. Find Mn of your composite beam section;
2. The total nominal shear capacity Pn required to be designed along half length of beam between two beam surface can be conservatively estimated as: Vn = Mn/H.
3. Assume you are going to use the shear studs with epoxy and assume that the shear capacity of each stud is Sn. Then the total number of studs required for your entire beam length is N = 2Vn/Sn.
4. I assume you know how to determine the stud spacing and # of rows using L and beam width.

 

[oneintheeye]

sorry this is not a composite section. Without going into two much detail we have a section existing. The load will be increased, as this is a water retaining structure we need to use concrete. the proposal due to other contraints is to add concrete section to outside of wall thereby increasing the effective depth to the existing reinforcement. For this I need to determine the tie required between teh existing and new sections. I know how to determine for steel etc as this is a uniform material and the shear at an interface is easily determined. Reinforced concrete being a composite material and non uiniform cannot be determined in the same way as I understand it. p.s. I am UK based so UK codes.

 

[miecz]

Sorry, but I'm not in the UK. Composite action seems to be code specific, and the differences from one code to the next can be dramatic. Our concrete code offers two completely different design methods.