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IS 13935:2009 is the Indian Standard (BIS) for seismic evaluation, repair and strengthening of masonry buildings - guidelines. This standard provides guidelines for the seismic evaluation, repair, and strengthening of existing masonry buildings. It establishes a procedure for assessing damage, determining seismic vulnerability, and selecting appropriate retrofitting strategies to enhance the building's resistance to future earthquakes.
Seismic Evaluation, Repair and Strengthening of Masonry Buildings - Guidelines
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! This is a guideline document; engineering judgment is paramount, especially for heritage structures.
! The primary goal of strengthening is to ensure 'box action' by connecting walls, floors, and the roof, thereby improving the building's overall integrity.
! A thorough diagnosis of damage is crucial. Not all cracks are seismic; some may be due to settlement, thermal effects, or material degradation.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
masonrybrickstonereinforced concretesteelgroutFRP
International Equivalents
Similar International Standards
ASCE/SEI 41-17American Society of Civil Engineers (ASCE), USA
HighCurrent
Seismic Evaluation and Retrofit of Existing Buildings
Covers seismic evaluation and retrofit for various building types, with specific chapters dedicated to masonry.
EN 1998-3:2005European Committee for Standardization (CEN), Europe
HighCurrent
Eurocode 8: Design of structures for earthquake resistance - Part 3: Assessment and retrofitting of buildings
Provides detailed rules for the seismic assessment and retrofitting of existing buildings, including masonry structures.
NZSEE (2017) GuidelinesNew Zealand Society for Earthquake Engineering (NZSEE), New Zealand
HighCurrent
The Seismic Assessment of Existing Buildings
Comprehensive guidelines for seismic assessment of buildings, with strong emphasis on URM and historical structures.
FEMA P-154, 2015Federal Emergency Management Agency (FEMA), USA
MediumCurrent
Rapid Visual Screening of Buildings for Potential Seismic Hazards: A Handbook
Focuses on the initial rapid visual screening (RVS) phase, which is the first step of the process outlined in IS 13935.
Key Differences
≠IS 13935 is presented as a 'guideline' with more prescriptive recommendations, whereas ASCE 41 and Eurocode 8-3 provide a more rigorous, performance-based framework with multiple analysis procedures (Linear Static, Nonlinear Static 'Pushover', Nonlinear Dynamic).
≠IS 13935 provides simplified, deemed-to-comply values for material properties based on typical Indian construction. ASCE 41 and NZSEE guidelines provide more extensive procedures for determining material properties through in-situ testing and provide lower-bound default values when testing is not feasible.
≠The concept of 'Performance Levels' like Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP) is central to ASCE 41 and Eurocode 8-3, allowing for a nuanced retrofitting objective. IS 13935's objective is more generally focused on enhancing seismic resistance to a level comparable to new construction codes.
≠While many strengthening techniques are common, IS 13935 gives specific prescriptive details for techniques like RCC jacketing and seismic belts. International standards tend to be less prescriptive on detailing, instead requiring design to be based on calculated force and deformation demands.
Key Similarities
≈All standards advocate for a tiered evaluation approach, starting with a rapid preliminary assessment to identify and prioritize vulnerable buildings, followed by a detailed structural evaluation for high-risk cases.
≈All codes identify the same fundamental seismic deficiencies in masonry buildings, such as lack of structural integrity ('box action'), poor diaphragm-to-wall connections, excessive out-of-plane wall slenderness, and insufficient in-plane shear strength.
≈The core goal across all standards is to improve life safety by preventing collapse. This is achieved by strengthening connections, improving ductility, and ensuring a complete load path for seismic forces.
≈Many of the recommended retrofitting techniques are conceptually identical, including adding horizontal bands (ring beams/belts), improving wall-to-floor/roof anchorage, grouting/repointing masonry, and adding new structural elements like shear walls or frames.
Parameter Comparison
Parameter
IS Value
International
Source
Wall Slenderness Limit (h/t ratio) for out-of-plane stability
Varies by zone and stories; e.g., 15 for a single-story building in Seismic Zone V (as per IS 4326 reference).
Varies by performance level and bracing; e.g., ~13-16 for Collapse Prevention of an unbraced wall.
ASCE 41-17
Minimum RCC Jacketing Thickness
75 mm (Clause 8.2.3.2).
Typically 65-100 mm (2.5-4 inches), but designed based on demand rather than being a single prescriptive value.
FEMA 547 (guidance related to ASCE 41)
RCC Jacketing Reinforcement (Minimum)
8 mm diameter bars @ 150 mm c/c, both ways (Clause 8.2.3.2).
No single prescriptive minimum; reinforcement is calculated to meet shear and flexural demands.
ASCE 41-17
Basis for in-plane shear strength of URM
Based on a frictional-cohesive model: τ = (f_v0 + 0.6 * σ_d) / γ_m, where f_v0 is cohesion and σ_d is compressive stress.
Also based on a frictional-cohesive model, often expressed as V = (v_me) * A_n, where v_me depends on a basic shear strength and overburden pressure.
ASCE 41-17
Evaluation Trigger from Rapid Screening
A 'Seismic Priority Index' is calculated based on building attributes to create a priority list for detailed evaluation.
A final score 'S' is calculated. A score below a threshold (e.g., S < 2.0) typically triggers the need for a detailed evaluation.
FEMA P-154
Acceptance Criteria for Strengthening
Component capacities must be greater than calculated demands based on simplified analysis.
Component actions (forces or deformations) must be less than the capacity for a specified performance level (e.g., Life Safety).
EN 1998-3:2005
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Minimum compressive strength of cement-sand grout10 MPa
Minimum thickness of concrete jacket layer40 mm
Minimum grade of concrete for jacketingM15
Minimum diameter of reinforcing bars for splints and bandages8 mm
Maximum slenderness ratio (h/t) for load bearing walls20 for one or two storeys, 12 for more storeys
Key Formulas
SSI = C / D — Structural Safety Index, where C is lateral strength capacity and D is lateral strength demand
Tables & Referenced Sections
Key Tables
Table 1 - Classification of Damage to Masonry Buildings
Table 3 - Selection of Repair / Strengthening Scheme for a Building Component
Table A-1 - Basic Seismic Coefficient for Different Terrains
Key Clauses
Clause 5 - Classification of Damage
Clause 6 - Procedure for Seismic Evaluation
Clause 7 - Selection of Repair and Strengthening Techniques
Clause 8 - Repair and Strengthening Techniques (General)
Annex A - Damageability Assessment of Masonry Buildings
Five levels from D1 (Slight Damage) to D5 (Collapse), plus D0 for No Damage, as described in Table 1.
Does this code apply to new buildings?+
No, it is specifically for the evaluation and retrofitting of existing masonry buildings. New buildings should follow IS 1893 and IS 4326.
What is the first step in a seismic evaluation?+
A preliminary evaluation, which includes a rapid visual screening, review of drawings, and non-destructive testing if needed (Clause 6.2).
What is 'RC Jacketing'?+
It is a strengthening method where a layer of reinforced concrete is added around a masonry wall or pier to increase its strength, stiffness, and ductility (Clause 8.4).