Influence of the constructive features of RC existing buildings in their ductility and seismic performance

Abstract

This paper aims to analyse the ductility of existing buildings to evaluate its influence in their 14 seismic performance. This has been achieved through the retrospective analysis of an existing 15 building in accordance with current seismic codes. This study has revealed the lack of guidance 16 in the NCSE02 and the EC8 regarding the assessment of the ductility of existing buildings. This 17 manuscript proposes a methodology to assess the ductility of Spanish existing buildings. For this 18 purpose, this paper has implemented the American code procedure combined with the EC8 and 19 the Spanish seismic code (NCSE02) requirements. A two-storey RC frame school located in the 20 Spanish region of Huelva has been selected as a case study. Different versions of this school have 21 been compared: as built, designed according to current best practice, EC8 provisions and NCSE02 22 provisions. To do so, different constructive features have been varied according to each of the 23 ductility class requirements: geometrical properties and the reinforcement ratio of the structural 24 elements. Nonlinear static analyses have been carried out to obtain the displacement ductility 25 factor (μ) and the behaviour factor (q) of each model. Construction costs and the expected damage 26 index have been determined and compared. Results have shown that the best performance, 27 regarding the ductility and the costs, has been obtained with the models designed with deep 28 beams. Conversely, models with wide beams, and where only the reinforcement ratios have been 29 varied, have merely shown a slight enhancement of the resistant and ductile capacity. It has been 30 concluded that the ductility affects the shear capacity, the seismic performance and the expected 31 damage of RC buildings.