Selection of area of region of the city for Rapid Visual Screening

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Conduction of the RVS survey for the selected area by the two forms

Steps of methodology are as follows: 1) Selection of area of region of the city for Rapid Visual Screening. 2) Selection of two RVS forms proposed by Ningthaujam and Nanda [1] and FEMA. 3) Conduction of the RVS survey for the selected area by the two forms. 4) Calculation of Final Score using survey data by both the forms. 5) Categorization of damage grade of RC buildings as per final scores. 6) Comparison between the two RVS forms. 7) Identification of buildings requiring detailed seismic investigation.

A. Rapid Visual Screening The earthquake capacity of a building is estimated by means of seismic vulnerability procedures [1]. There are numerous methods that have been established to calculate the earthquake vulnerability of building [8]. Detailed seismic assessment is a precisely difficult and costly process and it is able to be conducted on a limited quantity of buildings [3,8]. Hence it is essential to employ simple procedures that can help to calculate the vulnerability outline of different types of buildings rapidly, so that the complex assessment procedures can be restricted to the critical buildings only [9]. Rapid visual screening (RVS) is such a method which is inexpensive procedure for recognizing the structures that are highly vulnerable that need to be evaluated in depth for suitable structure mitigation action [3,15]. The RVS is a score assigning procedure including determination of seismically risky structures by evaluating structural insufficiency [6]. This is generally conducted by walk around survey on site for individual building in the region selected [9]. A plenty of guidelines are offered by Federal Emergency Management Agency (FEMA) in United States for seismic hazard estimation and rehabilitation of buildings [7]. RVS procedure allows prioritizing the building to be additionally examined so that scientific and other resources can be more precisely employed [10]. The examination, data gathering and conclusion process usually conducted at the site and requires around half an hour depending upon the size of building [3]. The methodology is proposed on the basis of some key factors that influence the risk of seismic hazards for any structure which can be seismicity, soil conditions, type of structure, irregularities of the structure etc [9]. Vulnerability of structures can also be suggested by an expert who is working in this field [6].

B. Seismic Vulnerability Assessment The vulnerability of existing buildings is measured by calculating RVS scores employing numerical seismic hazard [9]. Once the building is recognized as seismically unsafe, such buildings shall be further evaluated by an experienced professional in seismic evaluation and design [15]. The five damage grades of EMS-98 are used to classify the level of vulnerability of the buildings surveyed. Final score of 2 is taken as cut off for the assessment below which further evaluation is recommended [2,3,7,8,9,10,15].

C. Building Parameters Various researches have proven that different building parameters affect the different damages of the building at the time of a strong ground shaking [1,15]. Major parameters affecting the performance of the building that are being used to calculate the score during the survey using the forms, are seismicity of the region, type of structure, plan and vertical irregularities, age of the buildings, type of soil etc.

D. Damage Grading System The procedure makes use of a damageability grading scheme as per European macroseismic scale 1998 (EMS-98) that necessitates the assessor to (1) recognize the primary lateral load-resisting system, and (2) recognize building characteristics that can adapt the seismic response predictable incorporating non-structural components [20]. Grade 2 is taken as cut off above which the buildings need to be further re-evaluated.