Philosophy and techniques of seismic retrofitting

ABSTRACT

The author presents the concept of seismic rehabilitation of buildings, from the perspective of a small developing country. The adopted solutions correspond to the common construction practice in the country but the expressed philosophy and criteria can be applied to other regions in the world. Costa Rica is characterized by a long tradition of seismic reinforcement of buildings, public and private. This has resulted in good structural behavior as shown during the intense seismic activity that affected the country between March 1990 and April 1991. The policy adopted by the Costa Rican government and other public institutions and the positive attitude shown by building owners, aware of the seismic hazard and the need to prevent economic losses, have resulted in an intense activity in the field of seismic rehabilitation of buildings. Different procedures and systems of structural strengthening and seismic rehabilitation are presented. Rules for structural configuration and strengthening are commented, as well as constructive details for jacketing of elements, connections, anchorage and continuity of reinforcement. The use of structual walls as an efficient way to add strength and, at the same time, control the flexibility of the existing system, in order to reduce lateral displacements and reduce nonstructural damage, is emphasized. Examples of seismic rehabilitation of buildings and their behavior during the three earthquakes that affected Costa Rica are presented (AU)