Miscellaneous Terms

IS 6461 (Part 11) — Cement Concrete: Glossary of Terms (First Revision, October 2024) · 2024 definitions.

Part 10 Part 12Definitions quoted verbatim from the BIS standard

Anchor Cl 3.1: In prestressed concrete, to lock the stressed tendon in position so that it will retain in stressed condition; in precast concrete construction, to attach the precast units to the building frame; in slabs on grade or walls, to fasten to rock or adjacent structures to prevent movement of the slab or wall with respect to the foundation, adjacent structure, or rock.
Anchorage Cl 3.2: I n post-tensioning, a device used to anchor the tendon to the concrete member; in pretensioning, a device used to anchor the tendon during hardening of the concrete; in precast concrete construction, the devices for attaching precast units to the building frame; in slab or wall construction, the device used to anchor the slab or wall to the foundation, rock, or adjacent structure.
Anchorage Bond Stress Cl 3.3: The bar forces divided by the product of the bar perimeter or perimeters and the embedment length.
Anchorage Deformation or Slip Cl 3.4: The loss of elongation or stress in the tendons of prestressed concrete due to the deformation of the anchorage or slippage of the tendons in the a nchorage device when the prestressing force is transferred from the jack to the anchorage device.
Anchorage Zone Cl 3.7: In post-tensioning, the region adjace nt to the anchorage subjected to secondary stresses resulting from the distribution of the prestressing force; in pretensioning, the region in which the transfer bond stresses are developed.
Block Beam Cl 3.8: A flexural member composed of individual blocks which are joined together by prestressing.
Bonded Member Cl 3.9: A prestressed concrete member in which the tendons are bonded to the concrete either directly or through grouting.
Bonded Post Cl 3.10: Tensioning — Post-tensioned construction in which the annular spaces around the tendons are grouted after stressing, thereby bonding the tendon to the concrete section.
Bonded Tendon Cl 3.11: A prestressing tendon which is bo nded to the concrete either directly or through grouting.
Camber Cl 3.13: A slight, usually upward; curvature of a truss, beam, or form to improve appearance or to compensate for anticipated deflection, such as that produced as, a normal consequence of the eccentricity from the centre of gravity of the section of the prestressing tendons.
Cap Cables Cl 3.14: Short cables (tendons) introduced to prestressing the zone of negative bending only.
Characteristic Load Cl 3.15: Load which has 95 percent probability of not being exceeded during the life of the structure. 1 IS 6461 (Part 11) : 2024 To access Indian Standards click on the link below: https://www.services.bis.gov.in/php/BIS_2.0/bisconnect/knowyourstandards/Indian_standards/isdetails/
Characteristic Strength Cl 3.16: Strength of material below which not more than 5 percent of the test results are expected to fall.
Chemically Prestressing Cl 3.17: Concrete made with expansive cement and reinforcement under conditions such that the expansion of the cement induces tensile stress in the reinforcement so as to produce prestressed concrete.
Column/Strut Cl 3.18: A compression member, the effective length of which exceeds three times the least lateral dimension.
Concentric Tendons Cl 3.19: Tendons following a line coincident with the gravity axis of the prestressed concrete member.
Creep Cl 3.21: Time dependent deformation due to sustained load.
Creep Coefficient Cl 3.22: The ratio of creep strain to elastic strain in concrete.
Curvature Friction Cl 3.23: Friction resulting from bends or curves in the specified prestressing cable profile.
Dead End Cl 3.24: In the stressing of a tendon from one end only, the end opposite that to which stress is applied.
Dead Cl 3.25: End Anchorage — The anchorage at that end of a tendon which is opposite the jacking end.
Deflected Tendons Cl 3.26: Tendons which have a trajectory that is curved or bent with respect to the gravity axis of the concrete member.
Duct Cl 3.28: A hole formed in a concrete member to accommodate a tendon for post-tensioning; a pipe or runway for electric, telephone, or other utilities.
Eccentric Tendon Cl 3.29: A tendon which follows a trajectory not coincident with the gravity axis of the concrete member.
Effective Prestress Cl 3.30: The stress remaining in concrete due to prestressing after, all losses have occurred, excluding the effect of superimposed loads, but including effect of weight of member.
Elastic Shortening Cl 3.31: In prestressed concrete, the shortening of a member which occurs immediately on the application of forces induced by prestressing.
End Anchorage Cl 3.32: Mechanical device to trans mit prestressing force to the concrete in a post- tensioned member.
End Block Cl 3.33: An enlarged end section of a memb er designed to reduce anchorage stresses to allowable values.
Final Stress Cl 3.35: In prestressed concrete, the stress which exists after substantially all losses have occurred.
Final Tension Cl 3.36: The tension in the prestre ssing tendon corresponding to the state of the final prestress.
Flat Jack Cl 3.37: A hydraulic jack consisting of light gauge metal bent and welded to a flat shape which expands under internal pressure.
Flexural Bond Cl 3.38: In prestressed concrete, the stress between the concrete and the tendon which results from the application of external load.
Grouting Cl 3.39: The purpose of grouting is to pro vide permanent protection to the post-tensioned steel against corrosion and to develop bond between the prestressing steel and the surrounding structural concrete. The grout ensures the encasement of steel in an alkaline environment for corrosion protection and by filling the duct space, it prevents water collection and freezing.
Hoyer Effect Cl 3.41: In prestressed concrete, frictional forces which result from the tendency of the tendons to regain the diameter which they had before they were stressed.
Indented Wire Cl 3.42: Wire having machine-made su rface indentations intended to improve bond; depending on type of wire, may be used for either concrete reinforcement or pretensioning tendons.
Initial Prestress Cl 3.43: The stress or force applied to co ncrete at the time of stressing.
Initial Stresses Cl 3.44: The stresses occurring in prestre ssed concrete members before any losses occur.
Initial Tension Cl 3.45: The maximum stress indu ced in the prestressing tendon at the time of the stressing operation. 2 IS 6461 (Part 11) : 2024
Jack Cl 3.46: A mechanical device of varying design used to apply force to prestressing tendons, adjust elevation of forms or form supports, and raise weights by small distances.
Jacking Device Cl 3.48: The device used to stress the tendons for prestressed concrete; also, a device for raising a vertical slipform.
Jacking Force Cl 3.49: Temporary force exerted by the device which introduces tension into prestressing tendons.
Jacking Stress Cl 3.50: The maximum stress occurring in a prestressed tendon during stressing.
Linear Prestressing Cl 3.51: Prestressing as applied to linear members, such as beams and columns.
Linear Transformation Cl 3.52: The method of altering the trajectory of the prestressing tendon in any statically indeterminate prestressed structure by changing the location of the tendon at one or more interior supports without altering its position at the end supports and without changing the basic shape of the trajectory between any supports; linear transformation does not change the location of trajectory of the pressure line.
Loss of Prestress Cl 3.53: The reduction of the prestre ssing force which results from the combined effects of creep in the steel and creep and shrinkage of the concrete; does not normally include friction losses but may include. The effect of elastic deformation of the concrete.
Multielement Prestressing Cl 3.54: Prestressing accomplished by stressing an assembly of several individual structural elements as a means of producing one integrated structural member.
Multistage Stressing Cl 3.55: Prestressing performed in stages as the construction progresses.
Non Cl 3.56: Concordant Tendons — In statically in determinate structures, tendons that are not coincident with pressure line caused by the tendons.
Overstretching Cl 3.57: Stressing of tendons to a valu e higher than designed for the initial stress to: a) overcome frictional losses; b) temporarily overstress the steel to reduce steel creep that occurs after anchorage; and c) counteract loss of prestressing force that is caused by subsequent prestressing of other tendons.
Parallel Cl 3.58: Wire Unit — A post-tensioning tendon composed of a number of wires or strands which are approximately parallel.
Partial Prestressing Cl 3.59: Prestressing to a stress level such that, under design loads, tensile stresses exist in the precompressed tensile zone of the prestressed member.
Partial Release Cl 3.60: Release into a prestressed concrete member of a portion of the total prestress initially held wholly in the prestressed reinforcement.
Post Cl 3.61: Tensioning — A method of prestressing reinforced concrete in which tendons are tensioned after the concrete has hardened.
Pre Cl 3.62: Post-Tensioning — A method of fabricating prestressed concrete in which some of the tendons are pretensioned and a portion of the tendons are post-tensioned.
Prestressed Concrete Cl 3.63: Concrete in which internal stresses of such magnitude and distribution are introduced that the tensile stresses resulting from the service loads are counteracted to a desired degree; in reinforced concrete the prestress is commonly introduced by tensioning the tendons.
Pretensioning Cl 3.64: A method of prestressing reinforced concrete in which the tendons are tensioned before concreting.
Pretensioning Bed (or Bench) Cl 3.65: The casting bed on whic h pretensioned members are manufactured and which resists the pretensioning force prior to release.
Sequence Cl 3.66: Stressing Loss — In post- tensioning, the elastic loss in a stressed tendon resulting from the shortening of the member when additional tendons are stressed.
Sheath Cl 3.67: An enclosure in which post- tensioned tendons are encased to prevent bonding during concrete placement.
Sheathing Cl 3.68: The material forming the contact face of forms; also called lagging or sheeting.
Shrinkage Loss Cl 3.70: The loss of stress in the prestressing steel resulting from the shrinkage of the concrete.
Short Column Cl 3.71: A column, the effective length of which does not exceed 12 times the least lateral dimension. 3 IS 6461 (Part 11) : 2024
Slender Column Cl 3.72: A column, the effective length of which exceeds 12 times the least lateral dimension.
Strand Cl 3.73: A prestressing tendon composed of a number of wires most of which are twisted about a centre wire of core.
Strand Grip Cl 3.74: A device used to anchor strands.
Stress at Transfer Cl 3.75: The stress in both the prestressing tendon and the concrete at the stage when the prestressing tendon is released from the prestressing mechanism.
Stress Corrosion Cl 3.76: Corrosion of a metal accelerated by stress.
Stressing End Cl 3.77: In prestressed concrete, the end of the tendon from which the load is applied when tendons are stressed from one end only.
Stress Relaxation Cl 3.78: Stress loss resulting from strain developed when a constant length is maintained under stress.
Swift Cl 3.79: A reel or turntable on which prestressing tendons are placed to facilitate handling and placing.
Tendon Cl 3.80: A steel element, such as a wire, cable, bar, rod, or strand used to impart prestress to concrete when the elements tensioned.
Tendon Profile Cl 3.81: The path or trajectory of the prestressing tendon.
Threaded Anchorage Cl 3.82: An anchorage device which is provided with threads to facilitate attaching the jacking device and to effect the anchorage.
Trajectory of Prestressing Force Cl 3.83: The path along which the prestress is effective in a structure or member; it is coincident with the centre of gravity of the tendons for simple flexural members and statically indeterminate members which are prestressed with concordant tendons, but is not coincident with the centre of gravity of the tendons of a statically indeterminate stru cture which is prestressed with non-concordant tendons.
Transfer Cl 3.84: The act of transfering the stress in prestressing tendons from the jacks or pretensioning bed to the concrete member.
Transfer Bond Cl 3.85: In pretensioning, the bond stress resulting from the transfer of stress from the tendon to the concrete.
Transfer Strength Cl 3.87: The concrete strength required before stress is transferred from the stressing mechanism to the concrete.
Transmission Length Cl 3.88: The distance at the end of a pretensioned tendon necessary for the bond stress to develop the maximum tendon stress; sometimes called transfer length.
Transverse Prestress Cl 3.89: Prestress that is applied at right angles to the principal axis of a member.
Unbounded Member Cl 3.90: Post-tensioned, prestressed concrete element in which tensioning force is applied against end anchorages only, tendons being free to move within the element.
Unbounded Post Cl 3.91: Tensioning — Post- tensioning in which the tendons are not grouted after stressing.
Unbounded Tendon Cl 3.92: A tendon which is not bonded to the concrete section.
Wedge Anchorage Cl 3.93: A device for providing the means of anchoring a tendon by wedging.
Wobble Coefficient Cl 3.94: A coefficient used in determining the friction loss occurring in post - tensioning, which is assumed to account for the secondary curvature of the tendons.
Wobble Friction Cl 3.95: Friction caused by the unintended variation of the prestressing steel sheath or duct from its specified profile.

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