Background • What is Seismic Vulnerability? Susceptibility to damage during seismic events. Can be subjective or numerical quantity. The systematic approach or framework to quantify the seismic vulnerability is seismic vulnerability assessment Why is seismic vulnerability assessment needed ??? Answer….. Risk Management Risk Identification A major Exposure element to define the risk are buildings Evaluation of the vulnerability of Structures (Buildings) depends on many parameters • • • • • Building Typology Structural Systems Seismic Capacities Ground Condition Other structural aspects Insights about buildings behavior during seismic hazards Vulnerability Assessment Empirical Constructed from Historic Earthquake damage assessment Small no. of parameters on large number of buildings Analytical Hybrid Combination of the data from empirical methods in conjunction with analytical method Obtained form mathematical or computational modeling of exposure for an assumed potential level of hazard Large number of data on small building numbers Empirical Approach Rapid Visual Screening • First Step before detail damage assessment • Qualitative estimation from exterior observation Many countries have developed their own RVS technique Few to name are FEMA 154, Basic Hazard Score, BSH = -log10[P(collapse)] Final Score = BSH + SMs (score modifiers) National Research Council (NRC) Canada’s Structural Priority Index (SPI) = SI (Structural index) + NSI (Non Structural Index) Others are Japans Seismic Index approach NZ’s Initial Evaluation Procedure (IEP) followed by Detailed Seismic Assessment(DSA) etc., Empirical Approach Vulnerability Index Method 1. GNDT Approach Matrix of qualification coefficient ‘Ki‘ of Four vulnerability classes (A, B, C, D), each with 11 parameters having a fixed weightage(considering importance) for each parameter Vulnerability index Iv is evaluated using Iv value normalized between 0-100 from 0 to 382.5 such that 0 indicating the least vulnerable to 100 worst. Similarmatrix for RC building also , can be trasformed to Iv for Masonry , Using Empirical Approach Vulnerability Index Method 2. European Macro-seismic EMS Approach Risk-UE project • Building Typology Classes distributed to 6 vulnerability classes (A to F) least most • Such building are classified into four general typologies: Masonry, RC, Steel and Wooden • It categorizes the scale of damage to five grades D1(slight damage) to D5(collapsed) Empirical Approach Vulnerability Index Method 2. Combined GNDT and EMS Approach • Both method combined to certain correlation between them • Mean Damage Grade Md is defined such that (0<Md<6) where (I) represents the earthquake, hazard associated with macroseismic intensity, (V) is the vulnerability index, (Q) identifies the ductility of a particular construction, ranging from 1 to 4. Analytical Approach • Also called theoretical approach • Includes large number of parameters for small building numbers • Focuses no hazard (SGM) simulation to assess the performance behavior of the buildings Linear approach Non-Linear approach Static approach Dynamic approach Moreover the methods considering non linearity of the structures are more precise to assess the performance behavior and are mostly employed. • Non-Linear static analysis (NLSA) - Pushover analysis (POA) • Non-Linear time history analysis (NLTHA) - incremental dynamic • analysis (IDA) Analytical Approach Non Linear Static Pushover (NLSPO-Analysis) • Originally presented in in FEMA 273 and later updated in FEMA 356 Analytical Approach Non-Linear time history analysis (NLTHA) - incremental dynamic analysis (IDA) • Most exact and precise method to assess the seismic performance of a structure • capacity to model wide diversity of non-linear material behavior, irregularity in structures with geometric non-linearity, pounding effects, and higher mode effects in tall buildings • Concerned towards solving the dynamic equation of equilibrium • Different accelerograms (time histories ) actual events, modified and simulated are used Hybrid Approach Hybrid system considering both empirical and Analytical methods • Data from actual field scenarios collected using empirical methods are employed • Statistical data obtained from empirical methods are required to be sorted and categorized • Experimental findings and parameters determined from evaluation actual damage scenarios are used • Analysis through analytical techniques like NLPOA and NLTHA is done for a determined typology of buildings and failure categories