Detailing of Reinforcement in Concrete Casted Members

This presentation provides a general overview of the requirements of providing sufficient graphical details of the reinforcement provided in concrete casted beams, columns and other structural members.

1. DETAILING OF REINFORCEMENT SUBMITED BY VIPLAV SINGH B.ARCH 2 ND YEAR (B) ARCHITECTURAL STRUCTURES – IV RAR-403 SUBMITED TO ER.EKTA SINHA

2. CONTEXT INTRODUCTION REQUIREMENTS OF GOOD DETAILING NOMINAL COVER TO REINFORCEMENT SPACING OF REINFORCEMENT REINFORCEMENT REQUIREMENTS REINFORCEMENT SPLICING ANCHORING REINFORCING BARS IN FLEXURE CURTAILMENT OF TENSION REINFORCEMENT IN FLEXURAL MEMBERS BAR BENDING SCHEDULE

3. INTRODUCTION Detailing involves the involves the communication  detailing  contractors who build the structure. It communication of the engineer of the engineer’s design to the design to the contractors who build the structure. It involves the translation of a  involves the translation of a good structural design from the computer or calculation pad into good structural design from the computer or calculation pad into the final structure. Good detailing ensures that  Good detailing ensures that reinforcement  reinforcement   and concrete interact efficiently and concrete interact efficiently to provide  to provide  satisfactory behavior throughout the  satisfactory  complete range of loading. throughout the  complete range of loading. I n this seminar, guidelines for successful  successful   detailing in structural elements and  In this seminar, guidelines for  in structural elements and  connections are outlined.

4. REQUIREMENTS OF GOOD DETAILING To carry internal tensile forces, thereby imparting strength  and ductility To control flexural cracking To control direct tension cracking in restrained structures To carry compressive forces To provide restraint to bars in compression To provide confinement to concrete in compression To limit long‐term deformation To provide protection against spalling and  To provide temporary support for other reinforcement during  construction

5. NOMINAL COVER TO REINFORCEMENT Nominal cover, also called clear cover, is the distance between the outermost face of the concrete element and the outermost face of the reinforcement (including stirrups and links). It's a crucial aspect of designing reinforced concrete structures for several reasons: Durability: Protects steel reinforcement from corrosion caused by moisture, chlorides, and other environmental factors . Fire Resistance Provides an insulating layer of concrete to delay steel reaching high temperatures that could cause a loss of strength in a fire . Bond Strength The specific nominal cover requirements depend on various factors, including : Exposure Conditions: Structures exposed to harsh environments (e.g., seawater) typically require thicker covers. Concrete Grade : Higher strength concrete (e.g., M35 or higher) may allow for slightly reduced cover in some cases. Minimum Requirements : Building codes and standards (e.g., IS 456 in India) specify minimum nominal cover values based on bar diameter and member size.

6. SPACING OF REINFORCEMENT The minimum and maximum spacing reinforcement in concrete structural members such as beams and slabs are required as per standard codes. The minimum reinforcement spacing is based on maximum size of aggregates, so that concrete can be placed and compacted properly. The maximum reinforcement spacing based on depths of the beams and slabs to provide adequate support for bending moment and shear force in design. 1. Minimum Spacing between Bars in Tension The minimum vertical distance between two main bars shall be15 mm,  Two-third of the nominal size of coarse aggregate, or Maximum size of the bar or whichever is greater. 2. Maximum Spacing between Bars in Tension ( i )  The maximum spacing between two parallel main reinforcing bars shall be 3dor 300mm or whichever is less, and (ii)  The maximum spacing between two secondary parallel bars shall be 5dor 450 mm or whichever is less.

7. REINFORCEMENT REQUIREMENTS Reinforcement requirements refer to the characteristics that the reinforcement must have in order for the concrete structure to meet its requirements for strength and serviceability. These requirements include: The reinforcement must be of the right kind, of the right amount, and in the right place. Tensile strength is the most important requirement of steel reinforcement. Bond strength is important for the composite structure consisting of concrete and steel. Ductility, bendability, weldability, fatigue strength, corrosion resistance, and fire resistance are other important requirements.

8. REINFORCEMENT SPLICING Methods of Reinforcement Splicing Lap Splice Mechanical Splice Welded Splice 1.Lap Splices The lap splice is the most common and economic splice employed in the construction. The welded splices and mechanical splices require more labour and skill compared to lap splicing. 2.Mechanical Splice A mechanical splice or a joint make use of a coupler or a sleeve to splice two reinforcement bars. The mechanical splicing is a new type of splicing in Indian construction Industry. 3.Welded Splice Welded splicing is not commonly used as it may affect the strength of the reinforcement bars. Special conditions and rules are followed for welded splicing.

9. ANCHORING REINFORCING BARS IN FLEXURE The shear reinforcements are provided either in the form of a stirrup or bant up bars along with stirrups. The development length requirement for a stirrup deemed to have been satisfied if it is anchored round a bar of at least its own diameter for lengths beyond the curved portion of the anchorages shown in Figure The anchorage value of a bend shall be taken as four times the diameter of the bar for each 45" bend subject to a maximum of 16 dimes the diameter of the bar. The standard bends and standard hooks are shown in. For bars in compression, the projected length of bends, hooks and straight bars be-fond the bends shall be considered effective to be included in development length

10. CURTAILMENT OF TENSION REINFORCEMENT IN FLEXURAL MEMBERS To economize the design of a flexural member, the tensile bars are curtailed at the section beyond which it is no longer required to resist flexure (bending) given that the remaining reinforcement of the flexural member will be able to resist the bending moment and shear created on the flexural member safely. For a flexural member, tensile reinforcements, at first, are provided at critical sections (i.e. at sections where maximum positive or negative bending moment occur). Generally bending moment varies along the length of a member, the maximum amount of tensile reinforcement need not be continued for the whole length and hence curtailment is necessitated. The continuance of a tensile reinforcing bar beyond theoretical cut-off point is also necessitated for variation of bending moment diagram due to positioning of live load along the span. At the point of termination of a reinforcing bar shear resisting capacity of that section diminishes and stress concentration occurs. Therefore, additional shear reinforcements are provided to cope with the above exigencies (problems).

11. BAR BENDING SCHEDULE Fig: Typical Bar Bending Schedule Bar bending schedule or schedule of bars (BBS) is a list of reinforcement bars for a given reinforced concrete work item, and is presented in a tabular form for easy visual reference. Table of bar bending schedule summarizes all the needed particulars of bars - diameter, shape of bending, length of each bent and straight portions, angles of bending, total length of each bar, and number of each type of bar. This information is a great help in preparing an estimate of quantities

12. THANK YOU VIPLAV SINGH B.ARCH 2 ND YEAR (B)