SIMULATING A RESPONSE

Nonlinear analysis enables computer simulation of the behaviour of reinforced concrete structures in designed conditions. This paper describes the theoretical background, validation, and application of the SBETA simulation software and its new object-oriented version ATENA. There are over 100 users of SBETA worldwide, who use it for design and research and development. It is a tool for assessing the bearing capacity of designed or existing structures, investigating structural damage and failure, and developing new structural systems. SBETA uses a mathematical model that is based on the smeared crack concept and the damage approach. The model regards concrete without cracks as isotropic and concrete with cracks as orthotropic. The fixed crack model or the rotated crack model can be used to define the axes of orthotropy, which are the material axes of cracked concrete. The first example of experimental verification is a simple case of a reinforced concrete bar subjected to tension, whose crack propagation, crack width, and crack spacing were simulated. The second example, a shear wall, was simulated using a finite element model. An application example is outlined, where a nonlinear analysis with SBETA was performed to simulate the response to service loads of a Swiss bridge with cracked beams above its piers.