Response reduction factor R evaluation for soft story reinforced concrete buildings

In the Venezuelan Code Covenin 1756-2001 "Edificaciones Sismorresistentes", the analysis of soft-story buildings is carried out considering a response factor R, but recommends that the solicitations are multiplied for 1.30. In this paper this recommendation is evaluated, considering structural models in 3D with soft-story located in different heights. A response reduction factor R=6 is considered without to increase the design solicitations. Twelve reinforced concrete buildings are analyzed: 4 of 6-floor levels, 4 of 12-floor levels and 4 of 18-floor levels. Basic buildings of same heights and others with soft-story applied in inferior, intermediate and superior level are considered. The behavior of each structure and the influence of soft-story in the global response are analyzed, with static and the dynamic nonlinear methods and three different accelerograms: two real and one simulated. The results averages indicate that in 6-floor levels buildings the response factor R is 0.71 times that of COVENIN code, for 12 is 0.73 and 18-floor levels is 0.60. The average is a factor equal to 0.68. Carrying out a good design is not necessary to affect the solicitations for a factor 1.3 indicated in the Code, and is preferable to reduce the factor R indicated in Covenin 1756: 2001. Other recommendations are made to contribute to the specification given by the Coven in Code 1756-2001.