The structural engineering community often deals with the issue of inelastic incursions of the structural response. Although buildings situated in seismic regions are usually designed using elastic analysis, most encounter significant inelastic deformations when major events occur. In general, material nonlinearity is the most important source of nonlinearity considered in the dynamic analysis commonly performed in structural design. In this paper, the recent concept of the force analogy method for 3D structures is developed and integrated into an accurate computational efficient algorithmic routine for nonlinear dynamic analysis of reinforced concrete frames. Moreover, a unique straightforward mathematical model for the numerical implementation of degrading cyclic behavior of structural elements is proposed and further used to simulate the response of a 10 story reinforced concrete frame structure. A set of nonlinear dynamic analyses are performed using the proposed algorithm in order to assess the structural damage in case of different peak ground accelerations seismic recordings. The seismic structural damage is evaluated using both structural response parameters expressed in terms of displacement and energy concepts.

The retrofitting of a building requires an appreciation for the technical, economic and social aspects of the issue. Choosing the optimal solution depends on a large variety of criteria, the most important being the total cost, the construction time length (eventually with the possibility of continuous usage of the building), the ease of technologies application etc. The first part of this paper briefly presents classic and modern retrofitting technologies for industrial buildings. The second part represents a study case of a single storey industrial building retrofitting, using four different intervention options.