strut and tie evaluation of existing structures

huangyhg

strut and tie evaluation of existing structures
hello all;
does anyone know what the requirements would be in order to be able to apply strut and tie method (stm) to an existing structure?  i know that you are allowed to apply stm to b (beam) regions, but i am curious about any potential material requirements that existing structure might not meet.
are there any assumptions made in the development of the stm methods that might preclude older structures?
thanks,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...
existing structures may be not detailed correctly with respect to minimum steel and development of ties within nodes.
stm is just a method of analysis and could be applied to any structure.  the trick is finding a model that suits the reinforcing and loading layout of an existing structure.  it's easier to use stm on new structures since you can layout the reinforcing to suit your model.
stm could certainly be used for b-regions, where beam theory applies, though there isn't much need for it.  the method was developed to deal what aci calls d-regions, or disturbed regions, where beam theory doesn't apply (deep beams, near heavy point loads, dapped ends, corbels, etc.).
some of the problems you get with existing structures is things like distributed steel (e.g. stirrups) or redundant steel (e.g. vertical stirrups and diagonal ties).  you will need to find a way to conservatively simplify your model by perhaps ignoring redundant steel or lumping distributed steel.
stm is a developing art particularly in the analysis of nodes.
[23c and sunny in ottawa today - great for thanksgiving]

i was thinking more of material property issues, but i do greatly appreciate your input.  you've confirmed my thoughts...  it is appreciated.
regards,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...