I've been asked to design and build a rigid solid frame to test our reinforced masonry walls in the laboratory. the frame's span is 8 m and its Heigh should be at least 3.5 m. I know that our frame must be rigid enough to encounter possible loads with no big displacement so that we can be assure of our test data's reliability. the problem is that I have no idea how to design it. like what is the permitted displacement for a rigid frame? or should I use trusses, or it would be more economic to relay on moment resistance of columns.