A literature review on the seismic strengthening of reinforced concrete buildings, using steel bracings, infills and shear walls, is presented. Extensive experimental testing and numerical analyses of elements and structures have demonstrated the feasibility and effectiveness of all three measures for the increase of global strength and stiffness. In certain cases, they provide additional energy dissipation and help reducing irregularities. The selection of the most appropriate technique is based on desired performance levels and on economic and, possibly, other non-technical criteria. The results of previous studies clearly show that infilling an existing bay with reinforced concrete provides the highest increase in strength and stiffness. These studies also indicate that precast panels, steel bracings and masonry infills strengthened with fibre-reinforced polymers or textile-reinforced mortars are able to offer the same degree of improvement. The results available in literature, complemented by parametric numerical analyses, may provide the basis for the development of design guidelines with emphasis on strength and stiffness characteristics and on detailing of the connection between new and existing elements. Indeed, the development of models and their implementation in analysis software is a necessary step towards the wider application of these strengthening techniques. Regarding connections, a number of solutions have been tested; they provide adequate strength, but are labour-intensive and often result in steel reinforcement congestion.

JRC.G.4 - European laboratory for structural assessment