The 1993 standard offers detailed instructions to enhance the seismic resilience of low-strength masonry structures, such as brick and stone buildings with fragile mortars. It covers construction techniques, structural detailing, and cost-efficient reinforcement strategies tailored for different seismic zones. This guideline is crucial for professionals engaged in designing, evaluating, or retrofitting vulnerable masonry constructions against earthquakes.
Overview
The 1993 standard offers detailed instructions to enhance the seismic resilience of low-strength masonry structures, such as brick and stone buildings with fragile mortars. It covers construction techniques, structural detailing, and cost-efficient reinforcement strategies tailored for different seismic zones. This guideline is crucial for professionals engaged in designing, evaluating, or retrofitting vulnerable masonry constructions against earthquakes.
Audience
Contents
Structure
This section outlines the application of seismic strengthening measures for low-strength masonry constructions, emphasizing improving earthquake resistance. It includes definitions of seismic zones and coefficients, limitations on openings in load-bearing walls, and recommended strengthening methods categorized by building type and number of storeys.
Defines key terms such as seismic zones and coefficients, and explains building categories based on seismic risk and importance factors. Specifies restrictions on low-strength masonry use and outlines size and placement criteria for openings within bearing walls.
Details the applicable seismic zones (III to V) and the corresponding basic seismic coefficients derived from IS 1893. Explains the calculation of lateral seismic forces and the importance of horizontal ties for wall stability.
Emphasizes the necessity of construction continuity, describes types of low-strength masonry, categorizes buildings by seismic coefficients, and provides specifications for openings in bearing walls to ensure seismic performance.
Focuses on fire safety considerations following earthquakes, the reinforcement of openings with specific dimensions and spacing, requirements for built-in staircase walls, and the structural behavior of box-type masonry construction.
Describes appropriate mortar types and mix proportions for different masonry applications, including lime-sand, clay mud, and cement-sand mortars. Details the mortar usage around horizontal and vertical reinforcement and restrictions based on building categories.
Explains the classification of buildings into categories A through E based on seismic zone and importance factor, noting the obsolescence of category A and prohibitions on low-strength masonry in high-risk categories.
Details the types of low-strength masonry covered, including brickwork and stone masonry with weak mortars, associated restrictions by seismic category, and references to related IS codes for construction and design.
Specifies the categories of low-strength masonry such as brick masonry with weak mortars and random rubble or half-dressed stone masonry. Highlights the limitations on their usage across seismic categories.
Presents detailed mortar mix ratios for lime-sand, clay mud, and cement-sand mortars, including provisions for steel reinforcement cover and brick dimensions relevant to mortar application.
Describes size and location requirements for wall openings, wall thickness constraints, bonding methods including steel bars and through stones, and reinforcement approaches around openings.
Specifies dimensional limits and spacing for openings in load-bearing walls, reinforcement requirements when these limits are exceeded, and recommendations for reinforced concrete lining around openings.
Lists strengthening methods tailored to building categories and storeys, including horizontal and vertical reinforcement, bonding elements, and anchorage, with a summary of the strengthening techniques referenced in the standard.
Addresses the necessity of fire-resistant construction materials and detailing following seismic events, relationships between fire safety and building importance, and reinforcement considerations around wall openings.
Summarizes amendments made up to 2008, references related Indian Standards for seismic design, construction, and fire safety, and notes the committee responsible for the standard’s preparation.
Frequently Asked
To improve seismic resilience, use well-bonded brick or stone masonry with proper interlocking and avoid hollow or weak units. Incorporate through stones or bond elements at corners and junctions. Mortar should ideally be a cement-lime-sand mix (commonly 1:1:6 ratio) to ensure good ductility and adhesion. Avoid weak mud or lime-only mortars. Reinforce walls with horizontal bands and vertical bars at critical locations to enhance overall strength.
Openings should be kept small and centrally located to maintain lateral strength. For buildings in higher seismic categories, maintain minimum distances from inside corners (600 mm), pier widths between openings (500 mm), and vertical spacing (600 mm). If these limits are surpassed, reinforce openings with reinforced concrete linings containing two 8 mm diameter high-strength deformed bars in lintels and jambs. Additionally, install horizontal bands and vertical reinforcement at corners and junctions to improve wall integrity.
Concrete bands should span the full wall width with a minimum depth of 75 mm. Use at least two 8 mm diameter high-strength deformed bars longitudinally, tied with 6 mm diameter bars spaced at 150 mm centers. The mortar mix around reinforcement should be cement-sand at 1:3 ratio, with adequate cover (minimum 6 mm). Reinforcement must be continuous at corners and junctions to ensure effective resistance to horizontal bending and improve structural continuity.
This guideline applies specifically to low-strength masonry and wooden buildings located in seismic zones III, IV, and V. Buildings are categorized from A to E based on seismic zone and importance factor, with Category A now obsolete. The standard does not cover Zones I and II, and low-strength masonry is prohibited in the highest seismic risk category E.
Recommended reinforcement methods include horizontal bands at plinth, lintel, and roof levels; vertical reinforcement bars at corners and wall intersections; additional vertical reinforcement for three-storey buildings; use of through stones or bonding elements to improve wall cohesion; and anchoring floors and roofs to walls to maintain structural diaphragm action. These measures collectively improve ductility, load transfer, and reduce the risk of seismic damage.
Ask AI about any clause, requirement, or provision in IS 13828. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required