SEISMIC DESIGN AND LIFE CYCLE COST ANALYSIS OF A STEEL MRF BUILDING

Nowadays, the increasing demand for resilient and sustainable structures leads to design strategies that go beyond probabilistic criteria based on building’s life-safety. Performance-based seismic design approach assesses building and determines the probability of experiencing a certain loss. The current work examines a steel Moment Resisting Frame office building, located in L’Aquila, Italy, by applying FEMA P-58 framework. Losses assessment is performed, comparing the EC8 design scenario (PACT’s intensity-based analysis) and 2009 L’Aquila earthquake scenario (PACT’s scenario-based analysis). Annualized probabilities are computed as well through PACT’s time-based performance assessment, developing building’s life cycle cost analysis. The Moment Resisting Frame is designed through EC3 and EC8 rules, attending to ductility criteria and capacity design (i.e. hierarchy of strength). HEB400 and IPE360 sections are assigned respectively to the MRF’s columns and beams and an Openseespy model to represent the lateral seismic resistant frame is created. Columns are modelled as fiber-section elements to consider distributed plasticity, whereas end-beams are represented by non-linear hysteretic springs referring to the Lignos model. Firstly, Non-linear static analyses are conducted to establish elements capacity and pushover curve. Then, non-linear time history analyses are carried out by amplitude/scaling a suite of ground motion to the target EC8 spectrum, with the purpose to deeply understand cyclic behavior of the dissipative elements. Finally, IDAs are performed and fragilities curves referred to both local and global EDP, such as roof plastic hinge rotation and interstory drift, are obtained. Building’s damage states are thus depicted, and collapse fragility is obtained. FEMA P-58 framework is subsequently implemented to conduct the various PACT analyses (intensity, scenario, time-based). Non-linear analyses results are incorporated and arranged with a Monte Carlo procedure to develop hundreds of statistically obtained demand vectors. The study shows that L’Aquila scenario, compared to the design situation, results in 40% increase in median repair time and 60% increase in median repair cost. Moreover, structural components make a larger contribution to the overall losses than the design situation. However, time-based assessment illustrates the total repair time and cost evolution with the seismic intensity. Low intensities result in losses controlled by non-structural elements damage. As the seismic level increases, structural components make the dominant contribution, with occasional collapses and not repairable realization due to exceeding residual drift limits. At near median collapse intensities, residual drift and structural damage govern the losses.