Rebar makes earthquakes worse, as seen in California's freeway collapse. The rebar depends on the concrete to prevent corrosion, but that is only good for roughly 50 years. Rust causes expansion, which cases cracking. The outer concrete falls away, leaving rebar to get crushed under the load. The obvious fixes, like stainless steel rebar, have thermal expansion coefficients that don't match concrete, so instead you get cracking even without corrosion.
Lots of Roman stuff is still standing in areas that get earthquakes. The solution is to use a conservative design, with arches and thick walls. Domes are good. We can improve on this with 3D printing, using a structure like mammalian bone: solid near the surface, and spongy in the middle.
Would you be able to provide links to modern structures built with the methods you're describing or research about them? Does this conservative design resemble something like Gaudi's Sagrada Familia, or is that the wrong way to think about it?
Arch dams might be the only type of "contemporary" looking structure that is habitually made in this way out of unreinforced concrete.
Although Gaudi was interested in structural optimization (using catenary models), he is an outlier in terms of design. He didn't comprehensively consider seismic aspects, though apparently he didn't do too badly: https://blog.sagradafamilia.org/en/divulgation/seismic-activ...
Lots of Roman stuff is still standing in areas that get earthquakes. The solution is to use a conservative design, with arches and thick walls. Domes are good. We can improve on this with 3D printing, using a structure like mammalian bone: solid near the surface, and spongy in the middle.