12303-1987 Design of Rcc Hinges

7/28/2019 12303-1987 Design of Rcc Hinges

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I S; 12303rl 907IndianStandard

CRITERIA FORm DESIGN OF RCC HINGESi UDC 69188 6218882

( Reaffirmed 1998 )


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IS:12303-1

I ndian St andardCRITERIA FOR

DESIGN OF RCC HINGES

0. FOREWORD0.1 This Indian Standard was adopted by the der Bemmesung in Stahlbetonban ( ZweBureau of Indian Standards on 30 December Auflange >.1987, after the draft finalized by the Criteria forDesign of Special Structures Sectional Committee 0.3 It has been assumed in this standard thad been approved by the Civil Engineering the detailed design will be prepared by a strDivision Council. tural civil engineer experienced in the structuruse of the concrete and that the execution of 0.2 In the formulation of this standard, assistance work will be carried out under the direction has been derived from the following: a competent supervisor familiar with the maki

a) Ministry of Transport, UK : Rules for the of high quality concrete.design and use of Freyssinet concrete 0.4 For the purpose of deciding whether a parhinges in highway structures, London, cular requirement of this standard is compliHMSO, 1966 Memorandum No. 577/l; with, the final value, observed or calculateexnressina the result of a test or analysis, shb)cl

NAASRA Bridge Design Specification : be-rounded off in accordance with IS-: 2-196( fifth edition - 1976); and The number of significant places retained in LeCtUreS Notes On COUClXtC Sh3.XtUlW by rounded off value should be the same as that Dr F. Leonhardt Vorlesungen uber the specified value in this standard.Massirbau - Zweiter Teil, Sonder falle _- ~~ ~_______*Rules for rounding off numerical values ( revised

1. COPE1.1 he criteria given in this standard are inten-ded to be applied to only the Freyssinet hinge inwhich reinforcement through the throat, whenprovided, should not exceed 2 percent of thecross-sectional area of the throat. It is assumedthat the rotation takes place in the plane only.1.2 Limitation of Use- This type of hinge shouldnot be used where:

a) there is risk of collision with a structurecausing damage or displacement of thehinge, andb) under any loading there is a resultantuplift on all or a part of the hinge.

2. SYMBOLS2.1 For the purpose of this standard, the follow-ing letter symbols shall have the meaningindicated against each; where other symbols areused, they are explained at appropriate places:

At = effective area of throat - ( a.b or 2.4r2)

Ass = spalling reinforcement in the hinge mm*;Ast = transverse or main reinforcement in hinge in mm*;

a = minimum width of the throat measurin the plane of rotation in mm;b = minimum length of the throat measurnormal to the plane of rotation in m

b, = width of shoulder in mm;c = length of the hinge measured normalthe plane of rotation in mm;d = width of the hinge measured in plane of rotation in mm;dw = clear inside diameter of spiral in reforcement in mm;EC = modulus of elasticity of the concrete short term loading in MPa;

fck = characteristic compressive strength concrete in MPa;


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IS:12303 -1987h = height between the throats in case of b) Rapid hardening Portland cement con-double hinged bearing in mm: forming to IS : 8041-1978*, or

= total rotation of hinge c) High strength ordinary Portland cementconforming to IS : 8112-1976t.(radians >;$s = total rotation due to short term trans-

ient effects such as live load and tem-perature ( radian );+L = total rotation due to long term effectssuch as dead load, shrinkage, creep andannual temperature cycle (radians );hP = Ec.I.+, -= effective height of the throatM

( mm ) taken as 125 mm in the absenceof experimentally measured values;I = moment of inertia of the cross-sectionat the throat in mm4;

NOTS In hot humid climates, rapid hardeningcement shall not be used.3.3 Aggregates - Aggregates shall comply withthe requirements of IS : 383-1970:.

3.3.1 Aggregates for concrete shall be fromnatural sources which may have been naturallyreduced to size or crushed. Flaky and enlongat-ed material shall not be used.3.3.2 Size of Aggregates - The nominal maxi-mum size of aggregate shall be 10 mm in thezone covered by transverse mat reinforcement.

3.4 Reinforcement - The reinforcement shall beany of the following:K = notch factor of the hinge, that is, theratio of compressive stress at the edgeof the throat due to axial load to

a) Mild steel and medium tensile steel barsconforming to IS : 432 ( Part l&1982$,

M=

average compressive stress in the throatdue to axial loading = 15;moment required to produce rotation inN/mm;

b) Hot rolled deformed bars conforming toIS : 1786-198511,c) Cold twisted bars conforming to IS : 1786-198511,or

P = load per unit length of the throat inN/mm;d) Hard drawn steel wire fabric conformingto IS : 1566-19828.

Pm(1.x total maximum resolved component offorce acting on hinge = bdP2-4S2, inN;R = effective radius of curvature of hinge inmm;

r = radius at the throat in case of circularshape in mm;S = shear force per unit length of the throatin N/mm;s = spacing of stirrups or pitch of spiralreinforcement in mm; andt = throat thickness in mm.

3.4.1 All reinforcement shall be free fromloose mill scales, loose rust and coats of paints,oil, mud or other coatings which may destroy orreduce bond.

3.4.2 The modulus of elasticity of steel shallbe taken as 200 kNlmma.3.5 Concrete

3.5.1 Grade of Concret e - The grade of con-crete for the hinge shall not be inferior to M40conforming to IS : 456-1978**.3.5.2 In the absence of test data, the shortterm modulus of elasticity of concrete, EC inMPa shall be taken as:

3. MATERIALSEc=5 7OOd& in N/mma3.1 Unless otherwise specified, the materials andother requirements shall be generally conforming where fck characteristic compressive strengthof concrete in MPa.to the stipulations of IS : 456-1978* andIS : 1343-1980-t. *Specification for rapid hardeniog Portland cemen

3.2 Cement-The cement used shall be any of (first revision ).tspecification for high strength ordinary Portlandthe following with the prior approval of the cement.engineer-in-charge: $Specification for coarse and fine aggregates from

a) Ordinary or low heat Portland cement natural sources for concrete ( second revision ).conforming to IS : 269-1976L @pecification for mild steel and medium tensile steelbars and hard drawn steel wire for concrete reinforce-ment : Part 1 Mild steel and medium tensile steel bars

*Code of practice for plain and reinforced concrete ( third revision ).IjSpecification for high strength deformed steel bars


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lS:12303-19873.5.3 Creep and shrinkage effects shall betaken in accordance with IS : 1343-1980* unlessexperimental data is available.

4. GENERAL DESIGN REQUIREMENTS4.1 Loads and Forces

4.1.1 In structural design, account shall betaken of the dead, live and wind loads andforces such as those caused by earthquake,efiects due to shrinkage, creep, temperature, etc,where applicable.

b) Shrinkage cracks may occur in reinforthroats, in particular, while the aforces are still very small. These need be considered detrimental td the functiing of the hinge or to its final load carrycapacity provided precautions are takenprevent penetration of water and suquent corrosion.4

41.2 The general method of working out theloads and load combinations shall be as given inIS : 875-19641_, IS : 1893-1984$ and other stipu-lations covered in IS : 456-1978Ej.4.2 Basis for Designs

Construction practice shall generally such as to ensure earliest possible applition of self weight and dead load in types of concrete hinges to avoid shrinkacracks.For short term loading the behaviour the concrete is elastic.

4.2.1 Basic Assumptions - The following arethe assumptions for designing throat:a) Any reinforcement through the throat ofthe hinge shall be only nominal or such as

to account for handling stresses in case ofa precast hinge. The effects of the rein-forcement, when provided, shall beneglected.

440

For long term loading, the creep is proptional to the initial stress.In considering the transverse tensile foron either side of the throat, the tenstrength of the concrete is neglected.

*Code of practice for prestressed concrete (firstrevision ).tCode of practice for structural safety of buildings :Loading standards ( revised).$Criteria for earthquake resistant design of structures( foltrih revision ).

4.2.2 The shear across the throat shall exceed one-third of the co-existing axial load.4.3 Permissible Stresses

4.3.1 Concrete- The average compressi(P)stress- in the concrete at the throat shall (a)exceed 2fck or 100 MPa, whichever is less, wh

OCodeof practice for plain and reinforced concrete( third revision ). subjected to any loading combination as specififor appropriate structure under consideration

NOTCHESTHROAT

1A SIDE ELEVATION 1B END ELEVATION(TRANSVERSE) (LONGITUDINAL 1

EFFECTIVE AREAOF THROAT, At = a x b WIDTHOF THROAT


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IS :12303 1987CENTRE LINE

ENC

PARABOLA y2=0.07ax

ic DETAILS OF THROAT (ALT-I) 10 DETAILS OF THROAT ( ALT. II)FIG. 1 TYPICAL RECTANGULARHINGE-LAYOUT AND SHAPE

Tensile stresses in the throat shall not be permit-ted except for shrinkage stresses which may ariseduring construction.4.3.2 Reinforcement - The stresses in thetransverse mat reinforcement shall not exceedOSSf, subject to a maximum of 180 MPa.

4.4 Design of Throat4.4.1 The width of the throat shall be suchthat:a) the required short-term and long-termrotations are accommodated without caus-ing tensile stresses in the throat, and

b) the bending moment transmitted by thehinge is acceptable.

4.4.2 A recess of not less than 50 mm shalprovided at each end of the throat from the of the column or member containing the hiThe shape of the notch in the immediate vicof the throat shall approximate to a paraand merge into slightly diverging straight to the edges of the member or alternatively, have a slope of not less than 1 in 10 as showFig. 1.The above rules are equally applicable hinges with circular throat ( see Fig. 2 ).4.4.3 To prevent tensile stress in throat rotation is applied, it is necessary that maximum direct compressive stress at the

2A CIRCULAR HINGE WITHCIRCULAR MEMBER 2 B CIRCULAR HINGE WITHRECTANGULAR MEMBER


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1s : 12303 - of the throat shall be greater than or equal tothe maximum bending stress (see Fig. 3) whensubjected to any loading combination co-existing.This may be expressed as:

.Z EcqK2K hefwhere

2 EC 4 L- sum of the products ofand effective moduluscity ( MPa j.

If condition ( 4 > is not compatible with cotions ( 1 j, ( 2 j and ( 3 j, the situation marotations resolved by prestressing.of elasti- It is preferable to keep a < 03d mm.

In the absence of experimentally measuredvalue for the hinge being designed, the following ii) Throat thickness t: +>ymay be assumed: It is preferable to keep t < 20 mm.(5bS4L)ZEc+=Ec q iii) The recommended shape of notch:

h, = 125 mmK = 15

a) Width of shoulder br > 07 a mm.4.4.4 The design requirements of the throatshall be governed by the following:i) Throat width, a:

b) The recommended slope of notch Fig. 1 jtan fi = 01

a>50mm>&mm

(0(2)

iv) The rotational stiffness of the hingeA4 applied to structures = ( C EC4 )12he

--EFFECTIVEHEIGHT OFTHROAT, h,

/

I COMBINED STRESSESI WHEN CRACKING B,EGlNS/ ,

I


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IS : 12303 19874.5 Bending Moment Transmitted by the Hinge -For the purposes of this section only, it shall beassumed that when the maximum direct comp-ressive stress occurs at the side o f the throat, theeccentricity of the load is a/3 and the bending b)moment transmitted by the hinge is P.a c>3 d)4.6 Design for Bursting Reinforcement

Reinforcing fabric,Sets of closed ties, andSpiral reinforcement in case of circuhinge.

4.6.1 The reinforcement may consist of any, 4.6.2 Whichever type of reinforcement is usor a combination, of the following: the aim should be to cross the planes of pottial cracking by bars as close as possible suba) Parallel mats, each of which consists of a to minimum clear spacing limited to 20 mset of primary bars transverse to the plane Typical details are shown in Fig. 4 and 5.

of potential cracking and a set of secdary bars perpendicular to the primbars and spalling reinforcement,

. SIDE ELEVATION END ELEVATIONMAIN TRANSVERSESECONDARY LONGITUDINAL SPALLING REINFORCEMENTRElNFoRcEMENT(A,Oj ~REINFORCEME~T(A&

iP --+__; L___.---- :TlCALRODS

MAIN TRANSVERSE \REINFORCEMENT (AS+ALT. ARRANGEMENT OFMAT REINFORCEMENT

LSECONbARY LONGITUDINALREINFORCEMENT (A,,)PLAN AT AA

4A For Rectangular Section

PLAN AT 68


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IS:12303:198

TIERODS

CONDARY LONGITUDINALINFORCEMENTtAcr I-

TRANSVERSE

TIE

MAIN TRANSVERSERElNFORCEMENT(A,t)

L PIRALREINFORCEMENTt&r)

~BITUMEN ORANY ELASTICMATERIAL

FIG. 5 ALTERNATIVEARRANGEMENTOF HINGE REINFORCEMENTAll bars should extend to the faces of thecolumn subject to normal edge cover and beanchored adequately so that the yield stress ofthe bars is developed under ultimate loadconditions.4.6.3 In concrete hinges, the tensile burstingzones start very close to the hinge and thereinforcement should, therefore, start as close tothe hinge throat as practicable. This mat rein-forcement shall be placed starting from 01 d to07 d. The minimum clear cover for reinforce-ment shall be 25 mm in this zone [see Fig. 4(a)and (b)].

iii) Spalling reinforcementAss _ 003 a2 x Pm,, .At 085f, In mm2

4.6.4.2 Hinge with circular throat - Thebursting reinforcement shall be provided in theform of spiral of area :Pwhere

dw = clear inside diameter of spiral rein-forcement ( mm ) and shall be atleast 25 a or 5 r.4.6.4 The zones immediately adjacent to thehinge shall be reinforced to carry the bursting 4.6.5 In addition to the reinforcement in theforce generated by the concentrated load from bursting zones, there shall be sufficient longitu-the throat in accordance with the principles dinal and transverse reinforcement throughoutadopted for the design of anchorages in IS : the column to prevent propagation of bursting1343-1980*. crack along the centre plane of the column,Alternatively, the magnitude of the bursting 5. WORKMANSHIPforce may be taken as follows:4.6.4.1 Hinge with rectangular throat 5.1 General Requirements - Workmanship shall


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IS:12303-1987given below: recommended that it should be formed

a) Deviation from specified : &- 3 mmdimensions of cross-section of throatrecess below the throat level with the top forcement mat. The width.of the recess sbe slightly greater than the width of the thr

b) Deviation of alignment at : 3 mm, (MUX)throat with respect totheoretical position ofleast throat thickness

5.3 Curing - Throat of concrete shall be keptcontinuously in damp or wet condition by pond-ing or by covering with a layer of sacking,canvas, hessian or similar materials and keptconstantly wet for at least 14 days from the dateof placing concrete.

5.5 Protection of joint During ConstructionWherever possible, hinges shall be adequsupported to prevent rotation at the throat the time of casting to the completion ostructure incorporating it. The permisloads, rotation and shears during this pshall be related to each other and to the streof the concrete f ct in accordance with 4.4(2), 3 and (4); fck being replaced in ( 3 ) bwhen fct has a lesser value. Care shall be to see that the conditions in 1.2 do not aris5.4 Position of Construction Joints - Cons-truction joints shall not be formed through 5.6 Inspection - So far as practicable, provshould be made to enable hinges to be inspethe throat. Where a joint is necessary, it is in service.


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12303-1987 Design of Rcc Hinges