The uniaxial (direct) tensile test is not commonly used for masonry structures. Researches mostly rely on bond wrench or bending tests for masonry structures. My questions are:
What are the main reasons for the direct tensile test being used so little for masonry structures (the brittleness of the material? the low tensile strength? complexity in the boundary conditions, i.e. chances of introducing flexure in the specimen)?
Are there additional complicating factors with performing direct tensile tests on specimens retrieved from existing structures? Let's say one is able to retrieve a vertical drill core from a masonry structure, what are the additional problems one faces with performing a direct tensile test on such a specimen (compared to a lab made couplet specimen)? Is it perhaps the loaded faces being not completely parallel to each other?
Normally, masonary structures are not suitable for tension/bending . But such tests can be conducted on properly bonded masonary walls for one's professional knowledge. Such tests can be preferably tried on a reinforced masonary element to evaluate efficacy of system. It is because both the masonary and the interstises bond are of brittle nature.