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In Spain, there are numerous vulnerable buildings, such as reinforced concrete frames with waffle slabs or wide beams. The use of hysteretic energy dissipators for seismic protection of wide-beam buildings is proposed. This study focusses in 3 and 6-story representative buildings; each building is designed for no, moderate and mid seismicity (design PGA 0.0 g, 0.12 g and 0.23 g, respectively). The mechanical parameters of the dissipators are selected from two approaches: an algorithm aiming to obtain uniform cumulated plastic ductility along the height of the building and a simpler approach where the yielding forces of each dissipative device are chosen proportional to those induced by the equivalent static forces in the Spanish design code. The suitability of the proposed solutions is assessed through dynamic analyses for representative seismic records; the performance criteria are the reduction of the interstory drift, of the base shear, of the absolute accelerations, and of the cumulated plastic displacements in the structure and in the dissipators. Three cases are compared: bare frame (building without any bracing), protected frame (building with dissipators) and braced frame (building with rigid connections instead of dissipators). This research belongs to a wider initiative that includes testing and practical applications., Postprint (published version)

This work deals with seismic protection of steel building structures using hysteretic energy dissipators. The sensitivity of the performance of these systems to the design parameters of the dissipative devices is numerically investigated. Particularly, the influence of the vertical distribution of the yielding forces of the dissipators is deeply examined; two major approaches are compared. Comparison is established in terms of the response of a 15-story steel building subjected to the Lorca earthquake. Initial results seem to indicate little sensitivity of that response to the design yielding forces of the dissipators., Postprint (published version)

The recent earthquake in Lorca (11-05-2011) was the most destructive recorded event in Spain, despite its moderate magnitude. This paper describes the numerical simulation of the dynamic response to the main record of the Lorca earthquake of six 3 and 6-story buildings with one-way concrete slabs with wide beams; these buildings were designed without any seismic consideration. We have chosen this type of construction because it is potentially highly vulnerable. The six considered buildings were selected to represent a large number of buildings of this type in areas of low-to-medium seismicity (as Lorca) of Spain along the period 1974-1994. The results show that these buildings, even with the cooperation of the walls, do not have sufficient capacity to withstand the most severe component of the Lorca record., Peer Reviewed, Postprint (published version)

Published in Engineering structures by ELSEVIER. The original publication is available at http://www.sciencedirect.com/science/article/pii/S0141029612004774, A significant number of short-to-mid height RC buildings with wide beams have been constructed in areas of moderate seismicity of Spain, mainly for housing and administrative use. The buildings have a framed structure with one-way slabs; the wide beams constitute the distinctive characteristic, their depth being equal to that of the rest of the slab, thus providing a flat lower surface, convenient for construction and the layout of facilities. Seismic behavior in the direction of the wide beams appears to be deficient because of: (i) low lateral strength, mainly because of the small effective depth of the beams, (ii) inherent low ductility of the wide beams, generated by high amount of reinforcement, (iii) the big strut compressive forces developed inside the column-beam connections due to the low height of the beams, and (iv) the fact that the wide beams are wider than the columns, meaning that the contribution of the outer zones to the resistance of the beam-column joints is unreliable because there is no torsion reinforcement. In the orthogonal direction, the behavior is worse since the only members of the slabs that contribute to the lateral resistance are the joists and the façade beams. Moreover, these buildings were designed with codes that did not include ductility requirements and required only a low lateral resistance; indeed, in many cases, seismic action was not considered at all. Consequently, the seismic capacity of these structures is not reliable. The objective of this research is to assess numerically this capability, whereas further research will aim to propose retrofit strategies. The research approach consists of: (i) selecting a number of 3- story and 6-story buildings that represent the vast majority of the existing ones and (ii) evaluating their vulnerability through three types of analyses, namely: code-type, push-over and nonlinear dynamic analysis. Given the low lateral resistance of the main frames, the cooperation of the masonry infill wa, Peer Reviewed, Postprint (author’s final draft)

A number of short-to-mid height RC buildings with wide beams have been constructed in moderate-seismicity areas of Spain. The seismic behavior in the direction of the wide beams appears to be deficient because of low lateral strength, low ductility of the wide beams, big strut compressive forces inside the column-beam connections, and unreliable contribution of the spandrel zones of the wide beams. In the orthogonal direction, the behavior is worse since only the joists and the façade beams contribute to the lateral resistance. The objective is to assess the seismic capability of these structures; further research will involve proposing retrofit strategies. The research approach consists of selecting a number of representative buildings and evaluating their vulnerability by code-type, push-over and dynamic analyses. The cooperation of the masonry infill walls is accounted for. The main conclusion is that the seismic behavior of these buildings is inadequate in most of the situations., Postprint (published version)

Un número importante de edificios con vigas planas están situadas en zonas de sismicidad moderada de España. Estas construcciones fueron proyectadas con normas sísmicas que no requerían ductilidad y exigían una resistencia lateral inferior a la de los códigos actuales; incluso, en bastantes casos la acción sísmica no fue tenida en cuenta. En consecuencia, la capacidad sismorresistente de este tipo de estructuras es preocupante. El objetivo de esta investigación es evaluar esta capacidad. La metodología seguida consta de las siguientes etapas: (i) Estudio de las principales características de estos edificios y selección de un conjunto de edificios representativos. (ii) Análisis de la vulnerabilidad de estos edificios mediante cálculos estáticos (“push-over”) y cálculos dinámicos (a partir de acelerogramas escalados al espectro de proyecto actual); se considera el comportamiento horizontal en dos direcciones y se tiene en cuenta la cooperación de tabiques y cerramientos. Esta investigación se desarrolla a partir de un estudio similar efectuado sobre edificios con vigas planas situados en zonas de sismicidad media (como la zona adyacente a Granada). Dicho proyecto incorporó ensayos experimentales en uniones entre vigas planas y pilares; estos resultados son utilizados en este estudio., Postprint (published version)