IS 456:2000 code pdf download

The concrete between the links or the bars where no links exist shall be placed and compacted before initial setting of and the formwork should be of the same nominal size concrete commences and should not be subsequently as the nominal cover. Methods of placing should be such as Spacers, chairs and other supports detailed on to preclude segregaion. Care should be taken to drawings, together with such other supports as avoid displacement of reinforcement or movement may be necessary, should be used to maintain the of formwork.

As a general guidance, the maxi- specified nominal cover to the steel reinforcement. Over vibration and under vibration of connections, tests shall be made to prove that the joints concrete are harmful and should be avoided.

Vibration are of the full strength of bars connected. Welding of of very wet mixes should also be avoided. The it is desirable to avoid them. If this is not possible, period of curing shall not be less than 10 days for their number shall be minimized. Concreting shall be concrete exposed to dry and hot weather conditions.

Construction joints should above minimumperiods may be extended to 14 days. Such compounds shall be applied to all exposed uneven surface. It is recommended to clean out laitance surfaces of the concrete as soon as possible after the and cement slurry by using wire brush on the surface concrete has set. The surface may also be used to provide effective barrier prepared surface should be in a clean saturated surface against evaporation.

It is exceedingly difficult and costly to alter concrete Fresh concrete should be thoroughly vibrated near once placed. Hence, constant and strict supervision of construction joints so that mortar from the new concrete all the items of the construction is necessary during flows between large aggregates and develop proper the progress of the work, including the proportioning bond with old concrete.

Supervision is also of extreme importance to check the reinforcement and Where high shear resistance is required at the its placing before being covered. Sprayed curing membranes and release agents should The prevention of moisture loss from the concrete is particularly important if the-water- Part 1 or IS Part 2. The curing regime should also prevent the development of high temperature gradients within the concrete. The water-cement ratio shall not Exposed surfaces of concrete shall be kept exceed 0.

If the charge in the tremie is lost while the space into which concrete is to be deposited. Otherwise it may be leached and of the tremie method, the vertical end piece of become segregated. Concrete shall be deposited, the pipe line is always inserted sufficiently deep continuously until it is brought to the required height. The bucket shall be filled completely and pipes the lower end of which is always inserted lowered slowly to avoid backwash. The on the surface upon which the concrete is to be concrete emerging from the pipe pushes the deposited and when discharged, shall be material that has already been placed to the side withdrawn slowly until well above the concrete.

They shall be placed carefully in header batch of the mix or the entire contents the and stretcher courses so that the whole mass is. The tremie pipe shall interlocked. Bags used for this purpose shall be be not less than mm in diameter and shall free from deleterious materials. A separate and also to the faces of the concrete shall not lifting device shall be provided for each tremie exceed one metre.

Stone aggregate of not less pipe with its hopper at the upper end. Unless than 50 mm nor more than mm size shall be the lower end of the pipe is equipped with an deposited outside the steel cages over the full approved automatic check valve, the upper end area and height to be concreted with due care to of the pipe shall be plugged with a wadding of prevent displacement of the cages.

As the grouting proceeds, the concrete. It will be necessary to raise slowly the pipe shall be raised gradually up to a height of tremie in order to cause a uniform flow of the not more than 6 mm above its starting level concrete, but the tremie shall not be emptied so after which it may be withdrawn and placed into that water enters the pipe.

At all times after the the next cage for further grouting by the same placing of concrete is started and until all the procedure. Additional samples may be The amount of grout to be sent down shall be required for various purposes such as to determine the sufficient to fill all the voids which may be either strength of concrete at 7 days or at the time of striking ascertained or assumed as 55 percent of the the formwork, or to determine the duration of curing, volume to be concreted.

Additional samples may also be required for testing samples cured by The care shall be exercised not to disturb the concrete as specimen shall be tested as described in IS The individual If more, the test results of the sample are invalid. For this purpose the values should be arrived at based a The mean strength determined from any group on actual testing.

In all cases, the 28 days compressive of four consecutive test results compiles with strength specified in Table 2 shall alone be the criterion the appropriate limits in co1 2 of Table However, the hardened concrete Where applicable, use should The methods as considered in the design. If within 24 h of removal of the imposed probe penetration, pullout and maturity. If the recovery is less can supplement the data obtained from a limited than 80 percent, the structure shall be deemed to be number of cores.

These methods are based on measuring a concrete property that bears some unacceptable. The accuracy of these methods, With an other materials and of the workmanship, as verified appropriate degree of safety, they should sustain all by inspections, is adequate for safety, serviceability the loads and deformations of normal construction and and durability.

Account should compliance with clearly defined standards for be taken of accepted theories, experiment and materials, production, workmanship and also experience and the need to design for durability. Calculations alone do not produce safe, serviceable and durable structures. In structural design, account shall be taken of the dead, Unless more accurate calculations are If within 24 h of the removal Part 3 and IS Part 4 respectively.

The recovery after the second test should be at least 75 percent of the maximum deflection In this case only 0. Wind and seismic loading shall be treated as imposed loading. Under transient wind load the lateral sway at the top For seismic. Part 5. The fire resistance of a care shall be exercised by the designer to ensure structural element is expressed in terms of time in hours adequate safety for possible stress reversal. Fire resistance of concrete elements depends upondetails of member size, cover The stability of a structure as a whole against In cases where dead load provides the restoring moment, Restoring moment ilue to imposed loads ceilings and sacrificial steel in tensile zone, should be shall be ignored.

For unsymmetrical or very tall centre to centre distance shall be used. The assumptions made shall be consistent for all the Where a member is built into a masonry wall which For such a The simplifying assumptions as given in Table 13 Shear for Coeffkients Clauses For non- centroid of the area of tension reinforcement and the monolithic construction the design of the membershall maximum compression fibre, excluding the thickness be done keeping in view This will not apply to deep beams.

The shears computed at the face of the support shall be used in the design of the member at that section However, where simplified analysis using coefficients is adopted, In the absence of more accurate determination, the redistribution of moments shall not be done.

The deflection shall half the sum of the clear distances to the adjacent beams generally be limited to the following: on either side. For high stmngthdeformedbarsof gradeFe For a cantilever, the clear distance from the free end of the cantilever to the lateral restraint shall not Slabs spanning in one direction and continuous over d supports shall be designed according to the provisions aDDkabk to continuous beams.

If such supports are formed slab for one load does not overlap the effective due to beams which justify fixity at the support of slabs, width of slab for another load, both calculated then the effects on the supporting beam, such as, the as in a above, then the slab for each load can bending of the web in the transverse direction of the be designed separately. If the effective width beam and the torsion in thelongitudinal direction of the of slab for one load overlaps the effective width beam, wherever applicable, shall also be considered in of slab for an adjacent-load, the overlapping the design of the beam.

Oand above 2. Where this moment per metre width of slab shall be ratio is one, that is, where the transverse and calculated separately for each load according to longitudinal flexural rigidities are approximately its appropriate effective width of slab calculated equal, the value of effective width as found for solid as in a above and added together for design slabs may be used.

But as the ratio decreases, calculations. The procedure should be as be as given in The slabs spanning in two directions at right angles 2 Determine the points of contraflexure of the and carrying uniformly distributed load may be new support moments [from c ] with the designed by any acceptable theory or by using span moment [from l ]. For determining Extend half the support tension steel at each 3 -bending moments in slabs spanning in two directions end to at least an effective depth or 12 bar at right angles and carrying concentrated load, any diameters beyond the nearest point of accepted method approved by the engineer-in-charge contraflexure.

Table 26 for adjacent panels may differ significantly. Where bi-axial bending is considered, it is sufficient to ensure that eccentricity exceeds the The unsupported length, 1, of a compression member minimum about one axis at a time. Reinforcing steel of same type and grade shall be used b in beam and slab construction, it shall be the as main reinforcement in a structural member.

Bundled bars shall be enclosed within stirrups struts in each vertical plane, provided that to be or ties. Bundled bars shall be tied together to ensure an adequate support, two such struts shall the bars remaining together. Bars larger than 32 mm meet the columns at approximately the same diameter shall not be bundled, except in columns.

Such struts shall be of should be taken into consideration, where applicable adequate dimensions and shall have sufficient see afso IS The development length Ld is given by For bars in compression, the values of bond stress for b Stirrups-Notwithstanding any of the bars in tension shall be increased-by 25 percent. Hooks should normally The projected For limit state method of design, this stress shall not length of hooks, bends and straight lengths beyond bends if provided for a bar in compression, shall only exceed - 1.

For working Bent 4 tension bar at a re-entrant angle should be avoided. The excess stirrup area shall be not At least one-third of the total reinforcement provided less than 0.

Bars in a bundle shall terminate at different points cl For 36 mm and smaller bars, the continuing bars spaced apart by not less than 40 times the bar diameter provide double the area required for flexure at except for bundles stopping at a support. Adequate end anchorage shall be provided for tension Where splices are provided in the-reinforcing bars, they , b When a flexural member is part of the primary shall as far as possible be away from the sections of lateral load resisting system, the positive reinforcement required to be extended into the maximum stress and be staggered.

It is recommended support as described in a shall be anchored to that splices in flexural members should not be at sections where the bending moment is more than 50 develop its design stress in tension at the face percent of the moment of resistance; and not more than of the support. The compression. Where lap occurs for a tension bar located at: Where spacing limitations and the lapped bar or where the clear distance minimum concrete cover see Where both condition 1 and 2 apply, the lap The following shall apply for spacing of bars: NOTE-Splices in tension members shall be enclosed in spirals made of bus not less than 6 mm diameter with pitch a The horizontal distance between two parallel not more than mm.

NOTE4ldsdwrnutprccludethcuscoflaqex heof f When splicing of welded wire fabric is to be aggregatesbeyond the congested teinforcemt in tb carried out, lap splices of wires shall be made same mcmk, the size of -gates m8y be rsduced so that overlap measured between the extreme aroundcongested reinforcementto comply with thir provi8ioll.

W Greater horizontal. It is the immersed. It shall be not less than the diameter of the bar. Unless the calculation of crack widths shows that a In the case of columns of minimum dimension of mm or under, whose reinforcing bars a Beams - The horizontal distance between do not exceed 12 mm, a nominal cover of 25 mm may parallel reinforcement bars, or groups, near the be used. Structural Members 2 The horizontal distance between parallel The total area ofsuch reinforcement shall be not where less than 0.

Compression reinforcement The maximum spacing of shear reinforcement in beams shall be enclosed by stirrups for effective measured along the axis of the member shall not exceed lateral restraint. The arrangement of stirrups shall be 0. In no case shall the spacing The rules given in However, this value can be reduced to where 0. Wherebarsfrom B-6 torsion reinforcement shall be provided as below: b In any column that has a larger cross-sectional a The transverse reinforcement for torsion shall area than that required to support the load, be rectangular closed stirrups placed perpen- the minimum percentage of steel shall be dicular to the axis of the member.

Where 8 Spacing of longitudinal bars measured along flanges are in tension, a part of the main tension the periphery of the column shall not exceed reinforcement shall be distributed over the effective mm.

If the effective flange width reinforcement is not taken in account in strength exceeds one-tenth of the span, nominal longitudinal calculations, nominal longitudinal reinforcement reinforcement shall be provided in the outer portions not less than 0. The effective lateral ii Sixteen times the smallest diameter of support is given by transverse reinforcement the longitudinalreinforcement bar to be either in the form of circular rings capable of tied; and taking up circumferential tension or by iii mm.

The ends of the transverse 2 Diameter-The diameter of the polygonal reinforcement shall be properly anchored links or lateral ties shall be not less than one- [see Where an increased 2 If the longitudinal bars spaced at a distance of not exceeding 48 times the diameter of load on the column on the strength of the the tie are effectively tied in two directions, helical reinforcement is allowed for, the pitch additional longitudinal bars in between these of helical turns shall be not more than 7.

In other cases, the a compression member are placed in more requirements of Adequate times the diameter of the largest bar in horizontal support at the offset bends shall be treated the inner row see Fig.

Metal pression member are grouped not in ties or spirals so designed shall be placed near not contact and each group adequately tied with more than eight-bar diameters from the point of bend. Where column faces are offset 75 mm or more, determining the pitch and diameter of the splices of vertical bars adjacent to the offset face shall transverse reinforcement in accordance with be made by separate dowels overlapped as specified The diameter of such transverse in Normally structures occur.

Expansion joints shall be so provided that the exceeding 45 m in length are designed with one nor necessary movement occurs with a minimum more expansion joints. However in view of the large resistance at the joint. The structures adjacent to the number of factors involved in deciding the location, joint should preferably be supported on separate spacing and nature of expansion joints, the provision columns or walls but not necessarily on separate of expansion joint in reinforced cement concrete foundations.

Reinforcement shall not extend across structures should be left to the discretion of the an expansion joint and the break between the sections designer. IS gives the design considerations, shall be complete. All dimensions in millimetres. We just provide the link already available on the internet and in google drive for educational purposes only. If any way it violates the law or has any issues then kindly mail us [email protected] to request removal of the link.

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