Reinforced Concrete solid design using Stress analysis

[byronG86]

Hi I am using ROBOT and have a volumetric solid which has to be designed. The output of of solid elements are stresses however how would one design the reinforcement when the condition is not beam flexure theory? I see there is an ACI method using stress analysis, does anyone have any examples of this method utilized in any codes??

Any help or tips would be appreciated

Regards

Byron

 

[BeFEA]

Why would you need the reinforcement? Answer this question in order to find the solution yourself. For example, if you need the reinforcement for local failure, refer to Eurocode 2 for local failure (I am not familiar to American Codes). Or, you might need to check the stresses of an unreinforced concrete block in ROBOT, then consider building a strut and tie model if reinforcement is necessary.

 

[bkal]

It is very difficult to give any advice based on limited information you have provided, and the key one is why did you have to use solid elemnts.

If your structure is 'beam' like but modelled using solid elements, could you calculate sectional forces from stresses (i.e. cut your beam with a perpendicular plane and integrate the stresses to get forces and moments about its centroid). This is a very rough approach, but might give you some idea.

The international federtinon for structural concrete (CEB - FIB) has issuen a bulletin / state of the art report regarding this issue:

No. 45. Practitioners' guide to finite element modelling of reinforced concrete structures

and it has sections dealing with reinforcement calculations based on 3d stress analysis (I have not used it so cannot comment).

 

[byronG86]

Apologies Brisidii and bkal, I was away and unable to respond.

The design is for a capping beam for a quay wall. The Capping beam includes service tunnels and is supported on the caisson walls. I have been looking at an envelope of forces consisting of Bollard pull, fender load, crane load, shrinkage and differntial temperatures. The stresses show tensions at the top and bottom of the section of the beam with localised patches of tension. I have taken a step back and calculated alot by hand, however I would like to know how one designs the reinforcement to an almost patch like arrangement of stress. Tomorrow ill post an image.

I have integrated the the the stress and determined the reinforcement in direct tension, additionaly checked for cracking. However I do feel this is conservative.

I will try and get that book practitioners guide. I just find its odd how many people use FEA but dont know how to design the reinforcement if the gradient is not clear showing obvious bending.

Thanks