Study of RC structures modeling based on reformulated and extended constitutive relation of concrete

It has been hard to apply fast CG solvers for RC structures solid element model in FEM analysis because stiffness matrix is not symmetric and positive-definite. Implementation of reformulated constitutive relation of concrete in PDS-FEM is proposed as a solution, but its computational cost is high. Then, it is effective to implement tension part of the constitutive relation instead of performing failure analysis. We validate this newly implemented constitutive relation and make a RC shear wall model, based on previous experiment, for large-scale FEM analysis. We show that convergence is not assured under a certain element size using this model. Also, we propose that steel can be modeled as beam elements instead of solid elements. This is because load-displacement error of the former hybrid model is as small as the latter full solid model. Thus, we can use hybrid model as an alternative to full solid model, which leads to significant reduction of computational cost of RC-structures solid element model in FEM analysis. (author)