Published in 1987, this detailed handbook offers extensive guidance on the reinforcement and detailing of concrete structures for engineers and designers. It encompasses best practices in cutting, bending, placement, anchorage, and inspection of reinforcement across various concrete components such as beams, slabs, columns, walls, tanks, and retaining walls, ensuring structural safety and cost-effective steel use.
Overview
Published in 1987, this detailed handbook offers extensive guidance on the reinforcement and detailing of concrete structures for engineers and designers. It encompasses best practices in cutting, bending, placement, anchorage, and inspection of reinforcement across various concrete components such as beams, slabs, columns, walls, tanks, and retaining walls, ensuring structural safety and cost-effective steel use.
Audience
Contents
Structure
This section outlines detailed procedures for determining bending measurements of reinforcement bars essential for accurate bar bending schedules. It includes formulas for various bar shapes, such as straight bars with hooks, bars with angles, complex bars, and closed stirrups or links, along with explanations of key dimensional symbols and illustrative sketches.
This chapter summarizes the physical and mechanical characteristics of mild steel and medium tensile steel bars, including yield strength, tensile strength, and elongation. It also presents a shape coding system for reinforcement bars, requirements for bar schedules, specifications for hard-drawn steel wire fabric, and details on high strength deformed steel bars.
Details the recommended sheet sizes for structural drawings, essential dimensions to be displayed, required scales for sections and joint details, and methods to zone drawing sheets for clarity and organization.
Covers best practices for cutting steel bars using power shears, guidelines for bending and radiusing without heat treatment, overbending to compensate spring-back, visual inspections post-fabrication, and assembly techniques including tying, welding, and mechanical couplers.
Focuses on presenting reinforcement details in tabular schedules supported by sketches, clarifying abbreviations, and standard formats for welded wire fabric schedules and measurement formulas for bending dimensions.
Explains distribution methods for reinforcement in one-way and two-way footings, typical reinforcement details with bar sizes and spacing, and specifications for column reinforcement including ties and concrete grade requirements.
Describes requirements for closed stirrups in edge beams, minimum shear reinforcement areas and spacing, use of bent-up bars as shear reinforcement, and development length considerations for different bar types.
Discusses rules for curtailment of main reinforcement based on bending moment diagrams, necessity of side face reinforcement for deep beams, detailing of shear and torsion reinforcement, and continuity of main bars through beam haunches.
Provides specifications for welded wire fabric types, mesh sizes, wire diameters, mechanical properties, weight calculations, and design considerations for slab reinforcement including lap lengths and anchorage.
Outlines reinforcement layouts for stair flights and landings, including main and distribution bars, requirements for handrail support reinforcement, anchorage lengths, and use of flexible pads to accommodate stresses.
Details requirements for base reinforcement of circular tanks with double reinforcement layers, minimum reinforcement ratios for different steel types, reinforcement continuity in retaining walls, provisions for expansion joints, and protection against earth pressures.
Explains curtailment of reinforcement based on bending moments for various beam types, requirements for side face reinforcement, detailing of shear and torsion bars, and special considerations for deep beams with low span-to-depth ratios.
Evaluates different types of reinforcement supports and spacers based on economic and technical criteria, including mortar asbestos, cement asbestos, and plastic varieties, with guidance on selection, fixing methods, and suitability under various conditions.
Covers inspection requirements for welds according to IS 822-1970, edge preparation methods for manual metal arc welding, welding sequences, temperature controls during welding, and criteria for ensuring weld quality and strength.
Specifies lap weld dimensions to ensure full bar strength, allowable gaps between bars, welding procedures including electrode movement, joint location guidelines to avoid high-stress areas, and use of splice plates when necessary.
Frequently Asked
The recommended concrete cover tolerances per the standard specify nominal covers based on element type and bar location, such as a minimum of 25 mm or twice the bar diameter at bar ends, 40 mm or bar diameter for column longitudinal bars (with possible reduction for small bars), 25 mm or bar diameter for beam longitudinal reinforcement, and 15 mm or bar diameter for slab reinforcement. Tolerances allow cover reductions not exceeding one-third of the specified cover or 5 mm, whichever is smaller. Additional covers are prescribed for base slabs (100 mm), beams (40 mm), and columns (minimum 40 mm, increased to 75 mm in aggressive environments).
For bars up to 36 mm diameter, lap splices are permitted with transverse reinforcement (stirrups) that resist the full tensile force, including at least three stirrups on each side within the outer third of the lap length. For bars exceeding 36 mm diameter, welding is preferred; if welding is not feasible, lap splices must be enclosed with additional spirals or compact stirrups. Lap lengths depend on development length and bar size, with straight lengths at least the greater of 15 bar diameters or 200 mm. Splices should be staggered along the length with a minimum center-to-center spacing of 1.3 times the lap length. Direct tension members require spirals of at least 6 mm diameter spaced at 100 mm or less, with proper hooks or bends at bar ends.
The code specifies supports and spacers made from corrosion-resistant materials that do not damage concrete or compromise its appearance. Types include asbestos-cement blocks and plastic supports, with plastic supports further classified into chair-type—providing cradle-like support for heavy loads—and circular-type, which grip reinforcement directly and are preferable for vertical bars. Fixing methods include binding with mortar or asbestos cement and elastic gripping. Circular spacers are generally avoided on vertical bars in columns, favoring placement on horizontal bars instead. Proper fixing is essential to prevent displacement during concreting and under self-weight.
Steel consumption can be economized by utilizing high tensile steel, which can reduce steel mass requirements by approximately 33% compared to mild steel, with minimal cost difference. Choosing larger diameter bars decreases cost per unit length and enhances cage rigidity, reducing potential displacement during concrete pouring. Arranging secondary beam reinforcement over main beam bars can support slab reinforcement and reduce concrete cover needs; however, if the main beam is heavily stressed, reversing this arrangement may be more economical. These practices balance material efficiency with structural performance.
Inspection should conform to IS 822-1970 procedures, including visual, dimensional, and defect assessment. Welded joints must be staggered along the bar length, avoiding highly stressed zones. During welding, the temperature near the weld should not exceed 300°C immediately after each bead and should be below 250°C before starting the next bead, verified approximately using temperature indicating crayons. The welding sequence involves completing beads 1 to 4, pausing for cooling, rotating bars 180°, then welding beads 5 to 8, followed by a final bead for horizontal bars with continuous rotation. Critical welds must be tested to confirm strength equivalent to the parent bar. Proper edge preparation and clean fusion faces are essential to prevent cracks and defects.
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