International Journal of Engineering Research ISSN:2319-6890(online),2347-5013(print) Volume No.5 Issue: Special 3, pp: 591-594 27-28 Feb. 2016 NCASE@2016 doi : 10.17950/ijer/v5i3/016 Page 591 Development of Fragility Curves for RC Buildings Vazurkar U. Y., Chaudhari, D. J. Department of Applied Mechanics, Government College of Engineering, Amravati, Maharashtra, India-444604 E-mail: umeshvazurkar@gmail.com, dilipbhanu.chaudhari@gmail.com Abstract: The damage to the buildings during recent earthquakes has demonstrated the need of seismic evaluation which is used to predict the probability of damage to the building. This paper describes the vulnerability assessment of reinforced concrete buildings using fragility curves. Fragility curves are used to describe the probability of damage being exceeded a particular damage state. For the development of fragility curves, guidelines given by HAZUS technical manual have been used. For the analysis, the RC buildings were modelled in SAP2000 v14. Non-linear static analysis procedure is used for the analysis of RC buildings. The pushover analysis is carried out as per the ATC40 guidelines. Capacity curve is generated as a result of pushover analysis. Results from pushover analysis are used for plotting fragility curves. The Fragility Curves are plotted considering Spectral Displacement as a ground motion parameter. Various ‘damages states’ are used to describe the damage level of the buildinggiven in HAZUS technical manual. Finally, using constructed fragility curves the spectral displacement values that satisfy the ‘slight’, ‘moderate’, ‘extensive’, ‘complete’ performance level requirements were estimated. The fragility curves developed from the analysis were used to study the seismic performance of building models. Keywords: Fragility Curves, HAZUS, Damage States, Ground Motion Parameters I. Introduction Seismic vulnerability assessment is a method used for quantification of risk involved due to expected earthquake in a region. The vulnerability is usually represented in terms of either Damage Probability Matrices (DPM) or Vulnerability (Fragility) curves. The seismic vulnerability of structures is commonly expressed through probabilistic fragility functions representing the conditional probability of reaching or exceeding a predefined damage state given the measure of earthquake shaking. Fragility curves are the conditional probability of exceedance of response of a structure for a given ground motion intensity. Fragility curves are used commonly for the estimation of probability of structural damage due to earthquakes as a function of ground motion indices or other design parameters. The most basic inelastic method of seismic analysis is complete non-linear time history analysis. But this method is complex and requires much time for completion. Therefore, Non-linear static procedures are used in this paper for the generation of fragility curves as per the HAZUS [1] manual. Three building frame models were considered in this paper for the development of fragility curves. Spectral displacement is used as a ground motion parameter. SAP200 v14 is used for the modeling of building and pushover analysis. Results from pushover analysis are used for development of fragility curves. The infill walls are not considered in modeling of RC buildings II. Literature review The researchers have recognized that the need of vulnerability assessment for seismic evaluation of buildings. They have identified Fragility curves is one of the tool for vulnerability assessment. The literature has been referred from various research papers is illustrated. Murat and Zekeriya (2006) presented a study on Fragility analysis of mid-rise RC buildings. They had performed incremental dynamic analysis on 3, 5, 7 storey RC buildings using 12 artificial earthquake records.Yielding and collapse capacity of the buildings was determined from the analysis. They used PGA and elastic spectral displacement as ground motion parameters. Also they used inter-storey drift and spectral displacement values as a damage measurement parameter. Farsi, et.al. (2015) presented a work to estimate the seismic vulnerability of existing buildings in Algeria. For this purpose, capacity curves were developed for the reinforced concrete buildings using push-over method. In the modeling of nonlinearity three types of plastic hinges were considered which are Flexural plastic hinges (M2, M3), Compound compression and bending plastic hinges (PMM), and shear plastic hinges (V2, V3). The analysis was performed using ETABS software.Four performance levels, corresponding to the expected damage after an earthquake OL, IO, LS and CP were considered in the vulnerability assessment of buildings in Algeria. Elastic response spectra, plotted for each soil type in acceleration vs. period coordinates are based on estimates of seismic coefficients CA and CV presented in ATC- 40(4)report. Raipure P. (2015) presented a study on development of fragility curves for open ground storey buildings. She had used probabilistic seismic demand model (PSDM) as per power law for the generation of fragility curves. a typical ten storied OGS framed building was considered and the building considered is located in Seismic Zone-V. The design forces for the ground storey columns were evaluated based on various codes such as Indian, Euro, Israel, and Bulgarian suggested approach. She designed various OGS frames considering MF as 1.0, 2.1 (Israel), 2.5 (Indian), 3.0 (Bulgarian), and 4.68 (Euro). The performance of each building was studied using the fragility analysis method introduced by Cornell et. al (2002). Twenty computational models were developed in the program ETABs for nonlinear dynamics analysis for each case. For the analysis, a set of twenty natural time histories was selected.