Seismic Analysis of Reinforced Concrete Frames with a Scalar Damage Model

The analysis of the dynamic response of reinforced concrete frames subjected to earthquake still represents an open issue in the field of the civil engineering. Experimental tests are of difficult realisation and expensive in terms of cost and time because of the large geometrical dimension of the frames necessary for the result be effectively representative. For their flexibility and their cheapness numerical methods could override these drawbacks but they present even greater difficulties for the non linearity of the mechanical behaviour of the reinforced concrete and for the numerical effort that step-by-step dynamic analyses imply. A constitutive law for the material, to be used in the dynamic non-linear analysis of structures, must join the capability of well describe the material behaviour with the requirements of low computational weight and few number of material parameters. In literature (e.g. RILEM [1988]) a wide variety of constitutive models for concrete can be found, mainly based of the fracture and plasticity theories, but their application to real problem rarely have been done. In this work a two-parameter scalar damage model, developed by Faria and Oliver [1993], for the concrete and an elastoplastic uniaxial law for the reinforcing steel have been adopted to describe the global behaviour of the reinforced concrete. The application of the model to the simulation of the seismic response of a frame is presented (Scotta [1997]) and the effect of mansory infills on the global behaviour of the frame has been investigated. The reliability of the proposed numerical model is demonstrated by good agreement of the numerical results with the corresponding ones experimentally obtained by Negro and Verzelletti [1994,1996]. Reference • RILEM, International Union of Testing and Research Laboratories for Materials and Structures, “Fracture mechanics of concrete. From theory to applications. Parts A and B.”, RILEM Technical Committee 90, FMA, 1988. • Faria R., Oliver X., “A rate dependent plastic-damage constitutive model for large scale computation in concrete structures”, Monografia CIMNE, n. 17, Barcelona (Spain), 1993 • Negro P., Verzelletti G., Magonette G. E., Pinto A. V., “Tests on a four storeys full-scale R/C frames designed according to Eurocodes 8 and 2: preliminary report”, Report EUR 15879, European Commission, Joint Research Centre, Ispra, Italy, 1994. • Negro P., Verzelletti G., “Effect of infills on the global behaviour of r/c frames: energy considerations from pseudodynaic tests”, Earth. Eng. and Struct. Dynam., Vol. 25, pp. 753-773, 1996. • Scotta R., “Analisi meccanica di strutture in calcestruzzo mediante modelli di danno”, Phd. Thesis, University of Padova, Italy, 1997.