Achievements of Truss Models for Reinforced Concrete Structures

• Published in: Open journal of civil engineering 2012-09, Vol.2 (3), p.125-131
• Main Authors: Papadopoulos, P. G., Xenidis, H., Lazaridis, P., Diamantopoulos, A., Lambrou, P., Arethas, Y.
• Format: Article
• Language: English
• Subjects: Columns (structural); Curvature; Dynamic tests; Mathematical analysis; Nonlinear dynamics; Nonlinearity; Reinforced concrete; Trusses
• ISSN: 2164-3164; 2164-3172
• DOI: 10.4236/ojce.2012.23018

Achievements are presented for truss models of RC structures developed in previous years: 1. Two constitutive models, biaxial and triaxial, are based on regular trusses, with bars obeying nonlinear uniaxial sigma - epsilon laws of material under simulation; both models have been compared with test results and show a dependence of Poisson ratio on curvature of sigma - epsilon law. 2. A truss finite element has been used in the nonlinear static and dynamic analysis of plane RC frames; it has been compared with test results and describes, in a simple way, the formation of plastic hinges. 3. Thanks to the very simple geometry of a truss, the equilibrium equations can be easily written and the stiffness matrix can be easily updated, both with respect to the deformed truss, within each step of a static incremental loading or within each time step of a dynamic analysis, so that to take into account geometric nonlinearities. So the confinement of a RC column is interpreted as a structural stability effect of concrete. And a significant role of the transverse reinforcement is revealed, that of preventing, by its close spacing and sufficient amount, the buckling of inner longitudinal concrete struts, which would lead to a global instability of the RC column. 4. The proposed truss model is statically indeterminate, so it exhibits some features, which are not met by the "strut-and-tie" model.