Hi,
I am looking to understand how the design moments and shears are to be calculated when using triangular plates for concrete slab analysis.
For triangular plates the results are reported wrt the local plate axes. The 'Global moments' are also available from staad. However, how do the global moments relate to the twisting moments Mxy ? is this included ? or the global moments are purely the transformed local moment considering the skew angles of plates?
I have searched numerous discussions on web although no clear answer was found. In addition staad technical reference material also does not talk about deriving concrete design forces from the plate results. The Wood-Armer or Clarke-Neilson methods are not mentioned. These require the twisting moments Mxy to be added to the out-of-plane moments Mx or My in global directions. This only leaves an option of using quadrilateral elements with local axes aligned with the global rebar directions.
Although for more complicated structures it is not always possible to use quad elements and triangular plates are more preferable to generate quick and uniform meshing - especially the parametric meshing feature is useful. However, I am confused as to how the global orthogonal moments, shears and axial loads are determined when using trigular meshing in staad in relation to full consideration of twisting moments Mxy.
Please share your thoughts.