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IS 16447:2016 is the Indian Standard (BIS) for cyclone resistant design and construction of buildings using reinforced concrete - guidelines. This standard provides guidelines for designing and constructing new reinforced concrete buildings to be resistant to cyclones. It covers wind load estimation, structural planning and configuration, and specific detailing for critical components like roofs, openings, and foundations to ensure structural integrity under high-velocity winds and storm surges.
Provides guidelines for the cyclone resistant design and construction of buildings utilizing reinforced concrete.
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Disaster Resilience and Retrofitting
ASCE 7-16American Society of Civil Engineers (ASCE), USA
HighCurrent
Minimum Design Loads and Associated Criteria for Buildings and Other Structures
Specifies wind loads for all structures, with dedicated chapters and provisions for hurricane-prone regions.
AS/NZS 1170.2:2021Standards Australia / Standards New Zealand, Australia/New Zealand
HighCurrent
Structural design actions - Part 2: Wind actions
Provides wind load calculations with specific regions (C & D) and factors for cyclonic conditions.
Florida Building Code (FBC) 2023Florida Building Commission, USA
HighCurrent
Florida Building Code, Building
A regional code based on ASCE 7 with stricter requirements for High-Velocity Hurricane Zones (HVHZ).
EN 1991-1-4:2005European Committee for Standardization (CEN), Europe
MediumCurrent
Eurocode 1: Actions on structures - Part 1-4: General actions - Wind actions
Covers general wind actions but is less specific to tropical cyclone phenomena compared to other standards.
Key Differences
≠IS 16447 (via IS 875) uses a single 50-year return period for determining basic wind speed, whereas ASCE 7 uses risk-based categories, resulting in different return periods (from 300 to 3000 years) and higher wind speeds for more critical buildings.
≠ASCE 7 and the Florida Building Code mandate specific, standardized missile impact tests for glazing and doors in wind-borne debris regions. IS 16447 only provides a qualitative recommendation to protect such openings without specifying a test protocol.
≠ASCE 7 explicitly includes a Wind Directionality Factor (Kd=0.85 for buildings) which reduces the main wind force resisting system loads, acknowledging a lower probability of maximum winds striking from the most critical direction. IS 875 (Part 3) does not have a similar explicit reduction factor.
≠The definition of a 'partially enclosed' building, which leads to significantly higher internal pressures, is more stringent in ASCE 7, often leading to a building being classified as partially enclosed more readily than under the 'permeability' based rules of IS 875 (Part 3).
Key Similarities
≈All standards use a fundamental formula where wind pressure is proportional to the square of the design wind speed (p ∝ V²), reflecting the basic physics of fluid dynamics.
≈All codes recognize and quantify the effect of topography, including factors to account for wind speed-up over hills, ridges, and escarpments.
≈The design approach in all standards accounts for internal pressure, which can be positive or negative depending on the location and size of openings, and can significantly increase net loads on walls and roofs.
≈All cyclone/hurricane design standards place a strong emphasis on ensuring a continuous and robust load path from the roofing/cladding elements, through the structural system, and down to the foundation to resist uplift and lateral forces.
≈The concept of using non-dimensional external pressure coefficients (Cp) to determine pressure distributions on various building surfaces (walls, roofs) is a common methodology across all the standards.
Parameter Comparison
Parameter
IS Value
International
Source
Basic Wind Speed Basis
3-second gust, 50-year return period, uniform for all buildings.
3-second gust, variable return period based on Risk Category (e.g., 700 years for Risk Category II).
ASCE 7-16
Debris Impact Test Requirement
Recommended to protect openings; no specified test protocol.
Mandatory standardized large missile impact tests (e.g., 9-lb 2x4 at 50 fps) in wind-borne debris regions.
ASCE 7-16
Wind Directionality Factor (Kd) for Main Frame
1.0 (Implicitly, as no reduction factor is specified).
What is the main code for calculating wind load for this guideline?+
IS 875 (Part 3) is the primary standard for calculating wind loads, as specified in Clause 5.
What is the minimum grade of concrete recommended for cyclone-resistant buildings?+
A minimum of M25 grade concrete is recommended for all reinforced concrete work (Clause 7.2.1).
Does this code provide guidance on building shape and orientation?+
Yes, Clause 4.2 recommends simple rectangular or square shapes and suggests orienting the shorter side of the building towards the predominant wind direction.
Are there specific requirements for foundations?+
Yes, Clause 10 requires foundations to be designed to resist uplift forces and recommends a minimum depth of 1.5m below ground level where possible.