Target-drift seismic-force-based design of one-story reinforced concrete precast buildings considering the requirements of the second generation of the Eurocode 8 standard

Results are presented concerning the force-based design of a wide range of reinforced concrete, single-story precast buildings, considering the requirements of the new Eurocode 8 standard. The relevant criterion defining the cross-sectional dimensions of the columns was the 2% drift limitation. Buildings were designed considering a behavior factor of 3 and a 50% reduction in stiffness corresponding to the gross cross-section. The design evaluation, using a nonlinear pushover analysis, revealed that all the buildings could expect approximately twice the drift considered in the design with significant second-order effects, particularly in very tall columns. The main reasons for large discrepancies between the elastic and nonlinear analyses were the arbitrarily selected behavior factor and the arbitrarily selected reduction in stiffness corresponding to the gross cross-section (the stiffness considered in the design was approximately double what the nonlinear analysis revealed). The analysis revealed that these two quantities are closely correlated. Once the dimensions of the columns had been selected, the force and initial stiffness reduction could not be chosen arbitrarily. Correlations were determined between the column dimensions, theoretical stiffness reduction, seismic force reduction (behavior factor) and second-order effects. From these correlations, a new target-drift force-based design methodology was proposed. All considered buildings were redesigned using the proposed method. The results of the new design and the nonlinear-pushover-based analysis correlated well.