Abstract

Nowadays, there are a large number works focused on determining the seismic vulnerability of structures. This feature is not accidental, but rather the product of concern to the scientific, professional and organizations responsible for risk management community to reduce the destructive effects caused by earthquakes in the infrastructure and society. Globally destructive events that have occurred during the previous and present decades have contributed to this initiative; among them, the Sichuan, China (2008), Port au Prince, Haiti (2010), Maule, Chile (2010) or Tohoku, Japan (2011) earthquakes can be mentioned, which had as consequences many dead, injured and homeless people. It is well known that an earthquake can cause humanitarian disasters not only by the number of casualties and injured people but also for the destruction of cities where thousands of families live and work. All the above mentioned reasons reveal the need of revision and improvement of the seismic design codes, construction practices and policies that allow buildings to have a better performance against the strong ground motions. This is the context in which this work was developed. It contains results of a research entitled "Evaluation of seismic vulnerability of residential steel structures designed according to current Ecuadorian codes and the AISC seismic provisions for structural steel buildings" that has been developed in Ecuador with the support of Prometeo Project, sponsored by the Ministry of Science, Technology and Innovation (SENESCYT) of that Country. In Chapter 1, a study of the seismic vulnerability of moment-resisting frames steel structures recently built in the metropolitan area of Quito is made. The study has two parts: one that deals with the application of the code provisions in the execution of projects, using not only the NEC, but also international codes, particularly earthquake-resistant provisions of AISC. A qualitative-quantitative conventional method was also applied to assessing the seismic vulnerability of a set of selected buildings, representative of the predominant structural typology present in Ecuador. This chapter has been developed collaboratively with the participation of three students of ESPE, Henry Abalco, Germán Calderón and Hugo Velásquez, the authors of this work being their thesis advisors. In Chapter 2 is presented the methodology FEMA P695, to be applied in the systematic process of evaluation of the seismic vulnerability of the metal structures of Ecuador. The methodology is initially formulated for determining design factors of structural types, but its formulation, that combines deterministic and probabilistic methods, allows the direct determination of vulnerability by a collapse fragility curves, containing the probability of structure collapsing under the action of the maximum considered earthquake. The methodology requires the definition of a design space. This is achieved by the appropriate selection of a set of archetypes to assess the seismic performance of the most repeated buildings in the particular case of Ecuador. In Chapter 3, the complete results of the application of the methodology are presented. Special reference is made in this chapter to each of the seismic factors calculated in order to assess the vulnerability of the archetypes studied applying pseudo-static non-linear analysis and incremental dynamic analysis (IDA). As a result of the evaluation, some interesting findings that illustrate the seismic safety of archetypes designed according to the NEC are shown. The analysis of the results allows to obtain conclusions and recommendations on the earthquake resistant behavior and vulnerability of the residential steel structures of Ecuador. Finally, the authors wish to thank to SENESCYT that made possible with the financial and logistical support the development of this work. They also wish to thank to the Department of Earth Sciences and Construction of the University of the Army of Ecuador (ESPE), for providing all the technical facilities to develop research activities, and to the Lisandro Alvarado University Research Council (CDCHT), Venezuela.