Fragility Curves of Existing RC Buildings Based on Specific Structural Performance Levels

Abstract

In seismic risk mitigation policies, fragility functions of existing buildings play a fundamental role. In this paper, a procedure to develop analytical fragility curves for Moment Resisting Frame Reinforced Concrete buildings is presented. The design of the selected building typologies was performed according to the codes at the time of construction using force-based methods and the state\ud of the practice at the time of construction. A total of 216 building classes were defined, considering different ages, number of storeys, infill panels, plan dimensions, beam stiffness, and concrete strength. The investigated buildings can be considered low-engineered buildings, using no seismic codes or old seismic codes. The seismic capacity of the selected models representing the existing RC buildings has been evaluated through non-linear dynamic simulations. Seismic response has been analyzed, considering various peak and integral intensity measures and various response parameters, such as ductility demands and Interstorey Drift Ratio (IDR). A new relationship among structural performance, damage levels and interstorey drift ratios for each studied type is introduced, which is calibrated using the damage levels described in EMS98. It is important to highlight that in this study, different thresholds of IDR have been associated with different typologies, considering their different ductility member levels after their different structural responses. Fragility Curves (FCs) for the studied structural types are set up, developed and discussed

Novel Models and Tools to Evaluate the Economic Feasibility of Retrofitting Intervention

“…The probability of exceeding for specific damage levels is evaluated. In several works, the advantages and disadvantages of different FCs built approaches and analyses methods have been discussed [6], [7], [8].…”

“…Firstly, analytical FCs for several RC-MRF existing building types ( Figure 3) have been defined from previous NLDAs numerical results [6] and following the improved approach of [8]. More detailed information about structural, geometrical, and mechanical characteristics of each considered building types and details about NLDAs are reported in [6], [8] and [9]. Fragility curves have been defined considering the Housner intensity.…”

New Seismic Risk Index for Existing Buildings

“…This application would provide a fast and reliable evaluation of the seismic safety level of considered building types with regard to the national Italian territorial scale. The application is based on previous studies [12], [13] and consequent Fragility Curves conditioned to Housener intensity.…”

“…These latter have been interpreted in terms of damage level based on a specific Damage Model [12], [13]. The considered damage levels are linked to four Performance Levels considered by Italian (NTC08) and European (EC8) code: Operatively PL, Light Damage PL, Life Safety PL and Collapse PL.…”

Effect of Material Variability and Mechanical Eccentricity on the Seismic Vulnerability Assessment of Reinforced Concrete Buildings

“…The steps to determine the fragility curves are [39,40]: -Non-Linear static analysis for each random case; -PGA for each random case; -Mean value µPGA and standard deviation σPGA of all calculated PGA; -Determination of the probability cumulative function (PCF) as: Table 9 contains the P(x) values for both buildings. The corresponding fragility curves are shown in Figure 15.…”