Ductile behavior, reinforced concrete

Concrete structures typically contain steel reinforcement. Steel reinforcement exhibits rate effects and yields in a ductile manner until it breaks at an ultimate strain greater than approximately 20 percent. The reinforcement model plays an important role in modeling reinforced concrete behavior (Holomek Bajer 2012, Jiang et al. 2012). Our approach is to explicitly model the reinforcement (beam elements) separately from the concrete (hex elements) using an elasto-plastic material model with yielding, hardening, rate effects, and plastic strain-based failure. 

Similarly to ASCE 41, EC8-3 distinguishes between ductile and brittle actions. For nonlinear analyses, capacities are evaluated on the basis of deformation for ductile actions and strength for brittle ones. Column flexure is considered a ductile actirai, although interestingly strong column-weak beam behavior is enforced for steel moment frames rmly (not reinforced concrete). 

Fan C-P (1998) Seismic analysis, behavior, and retrofit of non-ductile reinforced concrete frame buildings with viscoelastic dampers. Phd Lehigh University, Bethlehem... 

Better joint behavior can be achieved using steel rods mnning through columns and the ends of beams and epoxied into place. This system takes advantage of the ductile behavior of the steel rod which can yield not only in tension but also in compression as buckling is prevented by the surrounding timber. The cychc load behavior is good, with characteristics similar to reinforced concrete. 

---