stas 10107-0-90 civil and industrial constructions (en)

8/2/2019 STAS 10107-0-90 Civil and Industrial Constructions (en)

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ICS 91.040.01; 91.140.90

ROMANIAN STANDARD STAS 10107/0-90

Classification index G 41

Supersedes:

10107/0-76

Previous editions:

1967;1976

CIVIL AND INDUSTRIAL CONSTRUCTIONSANALYSIS AND DESIGN OF CONCRETE, CONCRETE STEELAND PRESTRESSED CONCRETE STRUCTURAL ELEMENTS

CONSTRUCTII CIVILE SI INDUSTRIALE

CALCULUL SI ALCATUIREA ELEMENTELOR STRUCTURALE

DIN BETON, BETON ARMAT SI BETON PRECOMPRIMATCONCTRUCTIONS CIVILES ET INDUSTRIELLES

CALCUL AT CONCEPTION CONSTRUCTIVE DES ELEMENTS DE

RESISTANCE EN BETON, BETON ARME ET BETON

PRECOTRAINT

Validation date:

1990-12-01

CONTENT

1 GENERAL1.1 Scope1.2 Classification of structural elements and of their reinforcements...1.3 General principles of design and calculation2 MATERIALS...2.1 Concrete2.2 Reinforcement..3 CALCULATION OF REINFORCED CONCRETE ELEMENTS3.1 Limit states.3.2 The calculation of stressed bent, eccentrically compressed and eccentrically elongated

elements in the limit resistance state of normal sections3.3 The calculation of limit resistance states in inclined sections3.4 Special cases for verification of transversal reinforcements3.5 The calculation of elements in the limit resistance state exposed to twisty bending stresses ...3.6 The calculation of unitary stresses in concrete and reinforcements during the IInd work

phase, on elements exposed to bending, with or without axial

stresses3.7 Verifications in the limit fatigue state3.8 Verifications in the limit state of concrete cracking3.9 Verifications in the limit deformation state3.10 Additional specifications for the calculation of precast elements4 CALCULATION OF SIMPLE CONCRETE ELEMENTS4.1 Necessary verifications..4.2 Calculation eccentricity4.3 Utilization requirements.4.4 Eccentric compression with a high degree of eccentricity

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ASOCIAIA DE STANDARDIZARE DIN ROMNIA (ASRO),Adresa potal: str. Mendeleev 21-25, 70168, Bucureti 1, Direcia General: Tel.: +40 1 211.32.96; Fax: +40 1 210.08.33,

Direcia Standardizare: Tel. : +40 1 310.43.08; +40 1 310.43.09, Fax: +40 1 315.58.70,Direcia Publicaii: Serv. Vnzri/Abonamente: Tel: +40 1 212.77.25, +40 1 212.79.20, +40 1 212.77.23, +40 1 312.94.88 ;

Fax : +40 1 210.25.14, +40 1 212.76.20

ASRO Entire or partial multiplication or use of this standard in any kind of publications and by any means (electronically, mechanically,photocopy, micromedia etc.) is strictly forbidden without a prior written consent of ASRO


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STAS 10107/0-90 2

4.5 Eccentric compression with a low and medium degree of eccentricity..4.6 Slenderness influences.......................4.7 Cross force verificationsing4.8 Local compression verificationsing5 CALCULATION OF PRESTRESSED ELEMENTS5.1 Necessary verifications5.2 Determination of unitaryary stresses in concrete and prestressedreinforcement

5.3 Calculation of prestressed concrete elements in the limit resistance state5.4 Calculation of prestressed concrete elements in the fatigue state5.5 Calculation of prestressed concrete elements in the state of concrete cracking5.6 Calculation of prestressed concrete elements in the limit deformation state5.7 Calculation of transfer areas6 EXECUTION REQUIREMENTS FOR REINFORCED CONCRETE ELEMENTS6.1 Thickness of the concrete coat covering layer of reinforcements6.2 Reinforcement anchorage.6.3 Reinforcement binding..6.4 Additional specifications for pillars.6.5

Additional specification for beams6.6 Additional specifications for plates

6.7 Data that shall be included in the execution projects of reinforced concrete elements7 EXECUTION REQUIREMENTS FOR PRESTRESSED CONCRETE ELEMENTS.7.1 General specifications 7.2 Technical details and requirements that shall be included in the execution projects of

prestressed concrete elements

7.3 Specific specifications for elements with pre-stretched reinforcements7.4 Specific specifications for elements with post-stretched reinforcements7.5 Reinforcement of transfer areas..ANNEX A: ACTIVE WIDTH OF COMPRESSED FOUNDATION BOTTOM FOR T-SHAPED

SECTIONS..ANNEX B: SIMPLIFIED PROCEDURE IN THE CALCULATION OF REINFORCED

CONCRETE ELEMENTS EXPOSED TO AN INCLINED ECCENTRICAL

COMPRESSION IN THE LIMIT RESISTANCE STATE

ANNEX C: DATA FOR THE CALCULATION OF REINFORCED CONCRETE ELEMENTS

IN THE LIMIT STATE OF CONCRETE CRACKING

ANNEX D: TERMS SPECIFIC TO PRESTRESSED CONCRETE.ANNEX E: SIMPLIFIED CALCULATION OF CONCRETE LONG-TERM UNITARY

DEFORMATION

ANNEX F: THE CALCULATION OF CONCRETE LONG-TERM UNITARY

DEFORMATION

ANNEX G: TRANSMISSION AND ANCHORAGE LENGTH OF THE PRESTRETCHED

REINFORCEMENTS..

ANNEX H: CALCULATION OF STRESS LOSSES WITHIN PRE-STRETCHEDREINFORCEMENTS

ANNEX I: MAIN CHARACTERISTICS OF THE PRESTRESSING PROCEDURES IN THE

CASE OF POST-STRETCHED REINFORCEMENTS.

ANNEX J: CALCULATION POSITIONS AND LENGTHS OF POTENTIAL PLASTIC PARTSFOR STRUCTURES IN LAPPED FRAMES, EXPOSED TO SEISMIC

PRESSURES, DESIGNED FOR CALCULATION SEISMIC AREAS, FROM A

TO E

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42

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44

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57

62

63

68

68

69

72

74

77

8384

85

85

87

88

89

91

93

95

96

99

101

103

107

108

113

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STAS 10107/0-903

1 GENERAL

1.1 Scope

1.1.1 This standard settles the specifications with respect to the calculation and execution procedures of concrete,reinforced concrete and prestressed concrete structural elements used in civil, industrial and agro-zootechnical

constructions made of concrete with either heavy aggregates (normal concrete) or light, with compacted structure.

Provisions of specific technical regulations apply to elements made of cell concrete, concrete from higherclasses than those stipulated in this standard, and concrete with rigid reinforcements (metallic profiles), and to elements

executed by means of special technologies, which influence their characteristics and behavior.

In case of extensively used elements and structures, which are provided with specific technical regulations

(examples: precast concrete products for industrial plants, structures with monolithic diaphragms or made of precastpanels for storied buildings, platforms, foundations, bins, tanks, chimneys etc.), those details concerning the execution,

calculation and reinforcement requirements shall also be considered.

In case of constructions located in environments with temperatures from 50o

C to 80o

C, when stresses depend

on concrete contraction or slow flow, or on the relaxation efforts of prestressed reinforcements, calculation instructions

stipulated within specific technical regulations with respect to the influences that high temperature has on these

distortional features shall also be considered.This standard does not apply to constructions that are condeformationed to heavy exploitation conditions, such

as those systematically exposed to temperatures over 80o

C or below 35o

C.

1.1.2 Superior insurance measures as well as special prescriptions can be adopted in case of extremely importantconstructions, pointed out as being so by authorized institutions; projects as such receive the approval of legalauthorities.

1.1.3 When designing serial precast products, other calculation procedures and other execution prescriptions than theones mentioned in this standard can be also applied provided they have been theoretically proved and experimentally

confirmed.

1.1.4 Exposure to humidity and bad weather conditions, environmental aggressivity and specific factors ofexploitation shall be considered when designing concrete, reinforced concrete and prestressed concrete elements, in

order to guarantee their resistance over time. The following are settled in accordance with the above-mentioned features

and the specific technical regulations:

- the class of the concrete;- the technical conditions imposed on concrete structure (type and minimum cement dosage, type of

aggregates, degree of impermeability or frost cleftness, maximum A/C ratio);

- the structure of construction elements;- potentially necessary additional measures of safety.

1.2 Classification of structural elements and of their reinforcements

1.2.1 Considering their role, reinforcements of structural elements can be classified as follows:- resistance reinforcements, of which dimensions are analyzed so that they would take over stresses;- confinement reinforcements, which increase the longitudinal deformation capacity and resistance of

prestressed concrete areas due to limitations of transversal deformations;

- constructive reinforcements, of which dimensions are not mathematically resulted, but which arenecessary for conferring an appropriate behavior to resistance, ductility and fissures by taking over stresses that cannot

be quantified by means of common calculation;

- assembly reinforcements, of which main purpose is to maintain the position of other reinforcementsuntil concrete consolidation.

The same reinforcement can fulfill more than one of the above-mentioned roles.


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STAS 10107/0-90 4

1.2.2 Considering the role and quantity of reinforcements, structural elements can be classified as follows:- elements made of simple concrete (non-reinforced or slightly reinforced, with a reinforcement below the

minimum admitted for reinforced concrete elements);

- elements made of reinforced concrete with resistance reinforcements, which have not been prestressedand observe the minimum reinforcements requirements provided in this standard;

- elements made of prestressed concrete, which are provided with initial stresses by means of prestressedreinforcements that adhere with the concrete before or after the prestressing effort is transferred.

1.2.3 Considering the shape used in the calculation, structural elements are classified in: linear, surface, or massive.1.2.4 Considering their behavior to fractures, structural elements can be classified in:

- ductile, which display significant post-elastic deformations before breaking;- slightly ductile;- non-ductile.

NOTE: Structural elements are classified in more detail with respect to the ductility requirements for seismic endurance

within the clause 1.2.5.

1.2.5 Considering their way of taking over seismic stresses, structural elements are classified in three categories, asdescribed in the subclauses 1.2.5.1 1.2.5.3.

1.2.5.1 Elements which are part of anti-seismic structures, in seismic calculation areas from A to EThis category includes elements that have intended to be dimensioned in accordance with their role of

absorbing and dissipating the seismic energy.

For all these elements, execution and calculation prescriptions within this standard and other technical

regulations specific to each type of structure, are provided distinctively for each of the following three classes inaccordance with the estimated amplitude of post-elastic activities:

- class a: elements which acquire significant post-elastic deformations and consequently, need to beprovided with a ductility degree as required by the anti-seismic design prescriptions. For these elements, execution and

calculation provisions are differentiated, when necessary, for potential plastic components (components which are

designed to receive post-elastic deformations in case of strong earthquakes) and the rest of areas in the respectiveelements.

Determination of potential plastic components and estimation of their calculation length are performed in

accordance with the technical regulations specific to each type of structure.When it is possible to estimate accurately the position of potential plastic components by means of complex

analyses of the structure in the post-elastic field, the remaining components within that structure can be included in the

b class.

- class b: elements which are conditioned to maintain an elastic state under seismic pressures in order tobe rigid enough to function as bonds between different structural components (platforms that function as shields, frame

joints, vertical joints which turn structures made of big panels into monoliths etc.), or as sealing elements (walls ofliquid tanks, gas pressured recipients etc.); these elements are dimensioned and reinforced at a superior assurance

degree than the rest, in conformity with the provisions and specifications of the technical regulations for each type of

structure. This class also includes elements that have been designed to perform in the elastic state by means of a

structural plasticizing mechanism.

- class c: elements which remain in the elastic field during seismic pressures due to the limited stressesthe latter exert upon them; a minimum constructive reinforcement provides the necessary bearing capacity for an

elastically seismic response (example: barely stressed diaphragms in case of buildings with a few floors).

1.2.5.2 Elements which are part of anti-seismic structures, in the F seismic calculation area. These elements alsodifferentiate in the a, b, c classes, as described in the subclause 1.2.5.1.


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STAS 10107/0-905

1.2.5.3 Elements which are not part of anti-seismic structuresThis category includes elements that shift when exposed to horizontal stresses without displaying any

deformations (example: precast beams assembled on pillars, such as the main roof beams of industrial plants, sliding

beams etc.). This category also includes elements that are insignificantly influenced by seismic pressures because their

side deformations are prevented by more rigid elements (diaphragms or props).

1.3 General principles of design and calculation

1.3.1 The calculation of concrete, reinforced concrete or prestressed concrete elements is carried out in accordancewith the general calculation principles settled in STAS 10100/0-75 and STAS 10102-75, and consists of verifications

performed in absolute limit states or during normal exploitation.

In case of construction elements which display a different plan of statics, a different active section or different

stresses in the intermediary execution phases (removal of shuttering, control and assembly of precast products, partially

executed construction etc.) than in the final one, calculation is performed in the intermediary phases as well.

1.3.2 Elements which are part of anti-seismic structures (classified as shown in the subclause 1.2.5), and canundergo plastic deformations during earthquakes, shall be provided with a ductile capacity to dissipate the seismic

energy; their ductile capacity depends on the materials used in execution, on structure and on the dimensioning

processes. For this purpose, the following shall be considered when it comes to reinforced concrete elements:- reinforcements shall be made of ductile steel (PC 60, PC 52, OB 37);

NOTE: Steel with reduced ductility can be used only for elements in classes b and c.

- avoidance of non-ductile premature yields in the compressed parts of those elements which are subjectof bending pressures, with or without axial stresses, by setting superior limits of both the reinforcement percentage of

stretched areas and the pressure level of the axial compressive stress (limitation of compressed area within the sections

of elements);

- providing a sufficient confinement for transversal reinforcements of compressed parts with post-elasticdeformations;

- avoidance of premature yields in the inclined sections by setting superior limits of the pressure level incase of cross forces;

- providing an adequate anchorage of the reinforcements within the concrete.In case of reinforced concrete elements, the calculation and execution provisions with respect to the ductilityrequirements are settled in the 3 and 6 provisions of this standard, for both potential plastic parts and the rest.

In case of prestressed concrete elements which are included in the a class (classified as shown in the subclause

1.2.5), ductility is provided in conformity with specific technical regulations.

1.3.3 Elements, which are part of anti-seismic structures, shall have an adequate rigidity for side shifts in order toreduce both structural and non-structural elements degradations.

2 MATERIALS

2.1 Concrete

2.1.1 Classes of concrete2.1.1.1 The class of concrete is defined in accordance with the value of the characteristic resistance Rbk(compressionresistance determined on cubes with sides of 141 mm, 28 days after their execution as described in STAS 1275-88;

statistically speaking, 5% of the results can display a lower value than that of the compression resistance), in N/mm2.

Concrete classes for simple concrete, reinforced concrete and prestressed concrete elements are as follows

(according to STAS 3622-86): Bc 3.5; Bc 5; Bc 7.5; Bc 10; Bc 15; Bc 20; Bc 25; Bc 30; Bc 35; Bc 40; Bc 50; Bc 60.

Classes of concrete made of light aggregates (which demand resistance conditions) range from the Bc 7.5 class

to the Bc 35 class.

NOTE: In special technically and economically legitimate cases, classes Bc 22.5 and Bc 27.5. whose calculation valuesare determined by linear interpolation between the values settled in this standard for Bc 20 and Bc 25 classes, respectivelyBc 25 and Bc 30 classes, are also admitted.


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STAS 10107/0-90 6

2.1.1.2 Considering apparent density at 28 days after execution, concrete is classified in density categories inconformity with STAS 3622-86. Within the light concrete density category (10002000 kg/m

3), concrete with of light

aggregates are classified in density sub-categories as shown in table 1.

Table 1

Density sub-categoryApparent concrete density at 28 days

after execution

kg/m3

1.6

1.7

1.8

1.9

2.0

15011600

16011700

17011800

18011900

19012000

NOTES1 In case of construction elements made of light aggregates, density sub-categories are indicated in the execution projects.2 When the own weight of elements is not determined by means of direct measures, the superior limit of the apparent

density corresponding to each density sub-category in table 1 is supplemented with 50 kg/m3.

2.1.1.3 Concrete minimum classes for construction elements are presented in table 2.Table 2

Construction elements Concrete minimum class Exceptions

Elements made of simple concrete, whose

dimensions do not result from a resistance

calculation, and blocks made of simple concrete,

used for foundations with bearing boxes and blocks.

Bc 3.5; Bc 5 In case of elements which

have contacts with the

underground water Bc 7.5.

Elements made of simple concrete, whose

dimensions result from a resistance calculation,except blocks made of simple concrete, used for

foundations with bearing boxes and blocks.

Bc 7.5 In case of elements which

have contacts with theunderground water Bc 10.

Elements made of reinforced concrete with lowreinforcement percentage, displaying mainly

constructive reinforcements of OB 37 (foundations),

respectively OB 37 and PC 52 (foundations and

elevations).

Bc 10

Elements made of monolith concretePrecast reinforced concrete elements, exposed to

reduced stresses

Bc 15 In case of elements that areexposed to water pressures

Bc 20.

Precast reinforced concrete elements, except those

exposed to reduced stresses

Bc 20

PC 90 bars Bc 25Elements made of prestressed

concrete with prestressed

reinforcementsdrawn elements

(wires, strands,

braided wires)

Bc 30 Bc 25 is admitted from time

to time, depending on both

the importance of the

structural element and the

stresses exerted upon it.

In cases such as the following, when technically and economically attested, superior concrete classes than

those mentioned in table 2 can be adopted:

- when class superiority leads to a significant decreasing of the concrete section, or increases the ductilityof the rigidity of the compound;

- when structural elements at the bottom of high storied or overloaded buildings shall have their sectionsreduced in order to decrease the weight;

- to uniformalize the concrete class of one floor within a building characterized by a monolithic structure;- in aggressive environments, for those situations stipulated in the specific technical regulations;-

when required by the exploitation conditions (impermeability degree, frost cleftness, dynamic stresses)or the exposure regime determined by specific technical regulations.


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STAS 10107/0-907

2.1.2 Characteristic and calculation resistances2.1.2.1 When analyzing concrete, reinforced concrete and prestressed concrete elements, characteristic compressionand stretch resistances of the concrete are determined in accordance with the class of the concrete by means of

experimentally deducted relations:

- characteristic compression resistanceRck:

- characteristic stretch resistanceRtk, for heavy aggregates concretes (normal concrete):- characteristic stretch resistanceRtkfor concrete made of light aggregates:

where is the apparent density of light concrete, determined as described in the subclause 2.1.1.2.

The values of characteristic resistances are provided in table 3.

2.1.2.2 Concrete calculation resistances are determined by means of the following relations:bc

ckbccbcc

RmRmR

== * (4)

bt

tkbttbtt

RmRmR

== * (5)

where

Rc,Rtcalculation compression and stretch resistances of the concrete;

mbc, mbtcoefficients of compressed and stretched concrete work conditions;

bc, tc safety coefficients of compressed and stretched concrete.

Those values of the calculation resistances which are determined formbc = 1, mbt= 1, bc = 1.35, tc = 1.50, are

called basic values, markedRc*,Rt*, and provided in table 3 for each concrete class.

Table 3

Class of the concrete

Type of resistance Symbol Bc

3.5

Bc

5

Bc

7.5

Bc

10

Bc

15

Bc

20

Bc

25

Bc

30

Bc

35

Bc

40

Bc

50

Bc

60

Characteristic resistances of the concrete, N/mm2

Compression Rck 3 4.5 6.4 8.5 12.5 16.6 20.5 24.3 28.0 31.6 38.5 45.0

Normal concrete- - 0.76 0.92 1.19 1.43 1.65 1.86 2.03 2.20 2.51 2.78

1.60.59 0.72 0.93 - - - - - - -

1.7

1.8

0.64 0.77 1.00 1.20 1.38 1.56 -

Stretch

Concrete

with light

aggregate

s and the

densitysub-category:

1.9

2.0

Rtk

- - - 1.23 1.42 1.59 1.74

Calculation resistances of the concrete, basic values, N/mm2

Compression Rc* 2.2 3.2 4.7 6.5 9.5 12.5 15.0 18.0 20.522.5

*)

26.5

*)

31.5

*)

Normal concrete- - 0.50 0.60 0.80 0.95 1.10 1.25 1.35

1.45

*)

1.65

*)

1.85

*)

1.6- - 0.40 0.50 0.65 - - - - - - -

1.7

1.8 - - 0.45 0.55 0.70 0.80 0.90 1.00 - - - -

Stretch

Concretewith light

aggregates

and thedensity

sub-

category:

1.9

2.0

Rt*

- - - - - 0.85 0.95 1.05 1.10 - - -

*) Values are multiplied by a supplementary coefficient of 0.95.

Li ht concrete concrete


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STAS 10107/0-90 8

2.1.2.3 In case of prestressed concrete elements, the mean compression resistance on cubes, necessary whentransferring the prestressing forceRb0, is prescribed within the project draft in conformity with the transfer stresses, the

characteristics of prestressed reinforcement, and the technological execution conditions of the elements, but it will not

be lower than that provided in table 4.

Table 4

Class of the concrete element Bc 25 Bc 30 Bc 35 Bc 40 Bc 50 Bc 60Minimum admitted value forthe mean transfer resistance on

cubesRb0, N/mm2

25 28*)

32 35 42 40

*) If the maximum compression unitary stress at transfer does not exceed 0.4Rb0, 25 N/mm2 is also admitted.

Calculation transfer resistances, necessary when verifying the limit transfer resistance, are determined by

means of a conventional class of concrete Bc*, which is depicted from table 5 in accordance with the transfer resistance

Rb0 prescribed in the project draft. For Bc*determined as such, the calculation transfer resistance of the concrete is

depicted from table 3 by means of linear interpolation.

Table5

Rb0 25 28 32 35 38 42 45 49 52Conventional class of

concrete at transfer Bc* 17 20 24 27 30 33 36 40 42

2.1.2.4 Coefficients of concrete work conditions2.1.2.4.1 In case of reinforced concrete and prestressed concrete elements, appropriate values for the mbc and mbtcoefficients are provided in table 6, in accordance with the concrete casting position.

For all elements made of simple concrete or of concrete with light aggregates from the Bc 30 and Bc 35

classes, the values formbc and mbtcoefficients result by multiplying the values in table 6 by 0.9.

Table 6

Concrete casting position The smallest dimension of

the section mm

mbc = mbt

< 300 0.75Vertical, with a casting height > 1500 mm (pillars,

diaphragms, beams walls, walls with recipients etc.,

made of monolithic reinforced concrete), or inclined, with

moulds on all sides. 300 0.85

< 300 0.85Linear elements exposed to

eccentric compression(precast pillars etc.) 300 1.00


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2.1.2.4.3 For the fatigue calculation, the mbc coefficient determined in accordance with the subclause 2.1.2.4.1 ismultiplied by the mbc coefficient, which results from the following relation:

(6)

where

b coefficient of asymmetry, resulted from the relation:

b max maximum unitary stress within the concrete, in the compressed extreme fiber;b min minimum compression unitary stress within the concrete, in the same fiber.

b max and b min values are determined in the IInd

work phase, and result from the exploitation loadings

corresponding to verifications performed in the limit fatigue state.

For elements exposed to bending, the following can be considered:

whereMmin

EandMmax

Eare the minimum and the maximum moment of bending, resulted from exploitation loadings

corresponding to the limit fatigue state.

2.1.3 Other calculation characteristics2.1.3.1 The values of the elasticity modulus in case of common concrete exposed to a Eb compression for shortduration loadings, are provided in table 7.

Table 7

Class of the

concreteBc 7.5 Bc 10 Bc 15 Bc 20 Bc 25 Bc 30 Bc 35 Bc 40 Bc 50 Bc 60

Eb, N/mm2

14000 21000 24000 27000 30000 32500 34500 36000 38000 40000

In case of concrete made of light aggregates, the values of the elasticity modulus of the concrete exposed to

aEbu compression result from the following relation:

(7)

where

Eb elasticity modulus of common concrete included in the same class as the concrete made of light

aggregates;

b, bu apparent densities of both common concrete and concrete made of light aggregates.

The elasticity modulus in case of concrete exposed to stretching is considered equal to that of the concrete

exposed to compression.

Coefficient of transversal deformation: = 0.2Transversal elasticity modulus is Gb = 0.4Eb, respectively Gbu = 0.4 Ebu.

2.1.3.2 The coefficient of linear dilatation for concrete, reinforced concrete and prestressed concrete elements whentemperature ranges form 35

oto + 80

o, can be t = 1.10

-5in case of common concrete, and t = 0.810

-5in case of

concrete made of light aggregates.


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STAS 10107/0-90 10

2.1.4 diagrams (unitary stress specific deformation)In the calculation of the sections of reinforced concrete elements exposed to bending, with or without an

axial effort, the following diagrams are adopted in the cases below:

- the second degree curve and the horizontal elevated plane as shown in fig. 1 a are used for compressedparts of concrete elements, where the limit unitary deformation is bu = 3.5 in case of concrete classes up to Bc 35,respectively bu = 3.0 in case of classes above Bc 35;

- the bilinear diagram in fig. 1 b is used for compressed parts of elements made of light aggregates,- the second degree curve in fig 1 c is used for the stretched parts of concrete elements belonging to any

class of concrete.

NOTE: Diagrams in fig. 1 are valid only if the specifications of minimum reinforcement described in this standard areobserved. These diagrams can be used for potential plastic parts with a transversal reinforcement superior to theminimum one.

If technical and economic researches lead to a superior confinement degree, theRcand bu values can be subject of anappropriate supplementation in accordance with homologated experimental data so that they would suit the more

detailed calculation of the resistance and post-elastic deformation capacities.

2.1.5 Total specific deformationThe total specific deformation of the concrete, bt, is given by the concrete slow flow and contraction, and

results from the following relation, after deformations are consumed in time:

bdbbt += 0 (8)where

bo the initial fraction of specific deformation, which is determined by means of the elasticity modulus atshort-duration loadingsEb, provided in table 7;

bdthe long-duration fraction of specific deformation, which can be determined by a simplified calculation

using the relations provided in ANNEX E. In case a more detailed evaluation is needed, especially when analyzing the

tension losses within prestressed reinforcements (when reinforcement is performed in several stages, for instance),

relations provided in ANNEX F can be used.


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STAS 10107/0-9011

2.2 Reinforcement

2.2.1 Non-prestressed reinforcements2.2.1.1 The geometrical characteristics (diameters, tolerances, sections) of non-prestressed reinforcements, as well asthe mechanical delivery characteristics (fracture resistance under stress, flowing limit, tensile strength etc.) are

described in STAS 438/1,3-89 and STAS 438/2-80.

2.2.1.2 Steel with a superior resistance (in case of rolled bars: PC 52, PC 60) is usually used in executing theresistance reinforcements of reinforced concrete structural elements or the complementary non-prestressed

reinforcements of prestressed concrete elements, including the cross-ties whose dimensions result from calculation.

Shaped drawn wire STPB or smooth drawn wire STNB are used as many times as possible in executing the

reinforcement of surface elements (plates, walls) by means of welded nets, as well as the cross bars of the welded boxes

of beams.

NOTE: Instructions for using the STPB and STNB steel in reinforcing elements which are part of anti-seismic structures(reinforcement of vertical monolithic diaphragms or of those made of big precast panels, transversal reinforcements offrame rulers), are detailed in the specific technical regulations with respect of these structures, correlated with the general

principles of design and calculation as they are presented in the subclause 1.3.2.

OB 37 steel is usually used for either constructive reinforcements or resistance reinforcements, of whichdimensions depend on the conditions of minimum reinforcement percentage, minimum diameters, or minimum spacing

between bars; it is also used in case the reinforcements with superior resistances cannot be efficiently applied due to

some special conditions of normal exploitation.

2.2.1.3 Characteristic and calculation resistancesThe minimum values prescribed in product standards for a flow limit ofRp0,2 function as steel characteristic

resistances in case of non-prestressed reinforcementsRak.

Calculation resistanceRa depends on the characteristic resistance, and results from the following relation:

where

macoefficient (or wedge of coefficients) of reinforcement work conditionsa reinforcement safety coefficient, with an average value of 1.15 for OB 37, PC 52 and PC 60, and of 1.2 for

STNB.

Calculation resistance values forma= 1 are called basic values, and have been marked withRa*.

RakandRa* values for non-prestressed reinforcements are provided in table 8.

Table 8

Type of steel Nominal diameter mmCharacteristic resistanceRak

N/mm2

Calculation resistance

(basic values)Ra*,

N/mm2

612 420

1428 405PC 60

3240 395 350

614 355

1628 345300

PC 52

3240 335 290

612 255OB 37

1440 235210

34 190

4.57.1 440370

STNB and STPB

810 390 325

NOTE: Resistances provided in table 8 are also valid for some other types of homologated steel, which function asequivalents of the types mentioned in the table (for instance for PC 60, 25 G2 S steel).


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STAS 10107/0-90 12

Reinforcement calculation resistance Ra is considered as being equal with Ra* (ma = 1), except when

performing the calculation in the limit fatigue state when the calculation resistance results from the following relation:

where

ma

0coefficient of reduction the calculation resistance as a result of repeated stresses;

ma5

coefficient of the reinforcement welded joints .

ma0

and ma5

values are provided in tables 9 and 10, and they depend on the coefficient of skew a, resultedfrom the relation:

a min anda max are the minimum andmaximum unitary stresses in the considered reinforcement.

Table 9

*) Welded bindings are not admitted when < 0.Translation NOTE: The figures in Table 9 and Table 10, written with a coma (e.g: 0,30,0,95) are to be read with a dot

(e.g: 0.300.95)

2.2.1.4 Reinforcement elasticity modulus is:E = 210000 N/mm

2for PC 60, PC 52 and OB 37 steels

E= 200000 N/mm

2

for STNB and STPB

Coefficient of skew a

T e of steel

Welding procedureCoefficient of skew *aType of

steel

Reinforcement welded by

means of end to end pressing,smoothly polishing the

protuberances; shell weld in a

CO2 environment

Reinforcement welded bymeans of end-to-end

pressing*. Shell welded

reinforcements within a slag

bath with longitudinal

junctures. Reinforcement

welded by means of displacedeclipses, or of equal eclipses

and junction welded seams.

Point welded reinforcements.

Overlap weldedreinforcements.

Reinforcements welded by

means of equal eclipseswithout junction welded

seams.

Table 10


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2.2.1.5 a a diagrams (unitaryary stress - specific deformation)The conventional bilinear diagram with elevated plane, represented by means of solid lines in fig. 2 a, is used

for hot-rolled steel (PC 60, PC 52, OB 37); the conventional bilinear diagram with consolidation, represented by means

of solid lines in fig. 2 b, is used for drawn wires (STNB, STPB).

In fig. 2 a, the maximum unitary deformation to be used in the calculation has the following values:

au = 10 for common groups of stresses;au = 50 for groups of stresses that include seismic actions.

In case of the potential plastic parts of elements included in anti-seismic structures, the bilinear consolidation

diagram, represented by means of dotted line in fig. 2 a, is used in the calculation of rolled steel if estimated that

deformations stressed on elements attack the consolidation of reinforcements as well, and therefore, afflict the

dimensioning process.In case of drawn wires, the bilinear equivalent diagram, represented by means of a dot-dash line in fig. 2 b, is

used in the simplified calculation of the resistance.

2.2.1.6 In case of reinforcements made of some other types of steel than those presented in table 8, calculationcharacteristics and their practicability are settled in conformity with the provisions of product standards and of specific

technical regulations.

2.2.2. Prestressed reinforcements for prestressed concrete elements

2.2.2.1 Prestressed reinforcements are made of highly resistant steel, which takes the shape of round smooth wires(SBP), impressed wires (SPBA), braided wires (LBP), strands (TBP), bars, egg-shaped rifted wires.

Wires and strands can group together and form bundles.

Geometric, chemical mechanical and technological characteristics of prestressed reinforcements are in

accordance with the prescriptions of:

STAS 6482/2-80 for SBP;STAS 6482/3-80 for SBPA;

STAS 6482/4-80 for TBP.

Quality verifications instructions in case of steel wires and wire products for prestressed concrete are in

accordance with STAS 6482/1-73.

NOTE: This standard includes also provisions for PC 90 and LPB reinforcements.

2.2.2.2 Steel characteristic resistances for prestressed reinforcementsRpk, are considered with their minimum values as

they are prescribed in the product standards (mentioned in the subclause 2.2.2.1), as follows:

- tensile resistanceRrk, in case of SBP, SBPA, TBP and LBP reinforcements;- flowing limitR0,2 k, in case of PC reinforcements.Characteristic resistances for SBP, SBPA, TBP and PC 90 are provided in table 11, and those for other types of

reinforcements are in conformity with the product standards.


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2.2.2.3 Calculation resistances of prestressed reinforcements result from the following relation

where

p safety coefficient of prestressed reinforcements with the following values:

p= 1.25 for SBP, SBPA, TBC, and LBP;

p= 1.20 for PC 90 reinforcements.

Calculation resistances for SBP, SBPA, TBP and PC 90 are provided in table 11.

Table 11

NOTE: SBP reinforcements which display a diameter smaller than 3 mm is used only in case of special prescriptions .Translation NOTE: The figures in Table 9 and Table 10, written with a coma (e.g: 0,30,0,95) are to be read with a dot

(e.g: 0.300.95)

2.2.2.4 Calculation resistances of prestressed reinforcements made of highly resistant steel, which display otherattributes than those mentioned in the subclause 2.2.2.3, are settled in accordance with specific technical regulations.

2.2.2.5 Elasticity modulus of prestressed reinforcements is considered as described below:

Ep = 210000 N/mm2for PC reinforcements;

Ep = 200000 N/mm2for SBA and SBPA reinforcements;

Ep= 180000 N/mm2

for strands and braided wires.

2.2.2.6 The a a diagram for SBP, SBPA, and TBP steel is used in the calculation as shown in fig. 3, with the

following analytical representation:

- forp 0.6Rp

Type and quality of the reinforcement

Wire, bar or strand

diameter

mm

Characteristic

resistanceRpk

N/mm2

Calculation

resistanceRp

N/mm2


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STAS 10107/0-9015

- forp >0.6Rp

A conventional bilinear diagram as shown in fig. 2 a can be used in the calculation of PC steel.

2.2.2.7 The limit unitary breaking deformation of prestressed reinforcement display a r= 3 % value. The value of thelimit calculation unitary deformation of prestressed reinforcement, (symbol), is settled in accordance with the

hypotheses mentioned in the subclause 5.3.2.4.

3 THE CALCULATION OF REINFORCED CONCRETE ELEMENTS

3.1 Limit states

3.1.1 The calculation of the limit resistance states is performed for all reinforced concrete elements.In case of linear elements, the verifications is performed by means of comparison between the maximum

sectional stresses (axial stresses, moments of bending etc.), resulted from calculation loadings with capable sectional

stresses.

In case of surface elements, which are provided with calculation models in conformity with their behavior as

reinforced concrete elements (beams - walls, diaphragms), sectional stresses are determined on the basis of the above-

mentioned models.

In case of structures composed of surface elements (thin curved plates, assemblies of diaphragms whichfunction as spatial profiles with thin walls etc.), which are deprived of calculation models, the stressing state results

from elasticity theories, and consequently, unitary stresses are provided instead of sectional stresses; under these

circumstances, it is allowed to deduce the sectional stresses from the diagrams of unitary stresses provided they are

summed up on each section.In case of structures or structural subsets, which make available the evaluation of the global capable stress

(e.g: plane plates) by means of a static calculation in the limit equilibrium state, tests in the limit resistance states can be

performed by directly balancing the calculation stress with the capable one.

When performing a post-elastic detailed calculation of the structure, checking in the limit resistance state can

be achieved by imposing requirements not to exceed the limit specific concrete specific deformations (bu) and themaximum ones (au), visible within the most stressed parts of the reinforcement.

3.1.2 The influence of the slenderness of eccentrically prestressed elements for the analyses in the limit resistancestates

In case of structures composed of linear elements (bars), it is recommended to settle the general construction

solutions as well as the dimensions of the sections so that the increasing of bending moments due to influences exertedby the slenderness of prestressed elements (II

nddegree effects), would not exceed 50 %.

If this limit is observed, the evaluation of the slenderness influence will consist barely of increasing thebending moments due to II

nddegree effects; verifications in the limit state of losing the superficial stability (buckling)

are not necessary. Situations that allow the omission of IInd

degree effects in the calculation, as well as those that permit

their evaluation by means of simplified procedures are described in the subclause 3.2.6.


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STAS 10107/0-90 16

Surface elements with thin walls (diaphragms, curved thin plates, cannular towers), in case of which there are

no IInd

degree calculation procedures theoretically and experimentally confirmed, can have their IInd

degree effects

taken into account in a simplified manner, using global coefficients of reducing the concrete calculation resistance.

3.1.3 In case of calculation performed in the limit state of losing the position stability (overturning), the elementsfunction as rigid solids. When determining the overturning moment, its growth due to 2

nddegree effects shall be also

considered.

3.1.4 Structural elements exposed to repeated stresses, which can induce a fatigue state, are also checked in the limitfatigue state, in accordance with the clause 3.7.

3.1.5 The calculation in the limit state of fissure opening is performed in order to secure the reinforcement aspectand safety against corrosion, and to provide an improved sealing for elements that are directly exposed to water.

3.1.6 The calculation in the limit deformation state is performed in case of elements that can be afflicted by apotential excess of admitted deformations, which can cause flaws of the operative process, damages of the bulkheadspropped by the respective elements, or unpleasant feelings in traffic (on the platforms, or leathers etc.)

3.1.7 Evaluation of the capacity of taking over seismic stresses in case of structural elements and ensemblestructures as such.

In case of current constructions, it is allowed to test the capacity of taking over seismic stresses by means of

conventional stresses, determined in accordance with specific technical regulations and considered to operate statically

(code stresses). Under these circumstances, the calculation is limited to verificationsing the structural elements in the

limit resistance state, and the rigidity requirements in case of side displacements (limitation of the relative level

displacements), in conformity with the purpose and the importance of the construction. Ductility requirements

corresponding to the values of seismic code stresses will be achieved if the construction and dimensioning prescriptions

provided in this standard with respect to elements that are part of anti-seismic structures, are observed.

In case of constructions that display a special significance or a special design, it is recommended to

verifications the capacity of taking over seismic stresses on the basis of a non-linear dynamic calculation. Tests are

usually performed in case of highly recurrent constructions, which are exposed to significant seismic stresses. The non-

linear dynamic calculation is performed on the building as a whole, and consists of comparing the elasto-plastic

deformation capacity of the construction with the seismic deformation; in the calculation of both concrete and

reinforcement, mean calculation resistances are also considered as follows:

aa

cc

RR

RR

35.1

75.1

=

=

The b b diagram is as shown in fig. 1 a, replacing c with (symbol).Simplified post-elastic calculation procedures are also admitted if they are confirmed by comparisons with

non-linear dynamic analyses.

3.2 The calculation of bent, eccentrically compressed and eccentrically elongated elements in the limit resistance state ofnormal sections

3.2.1 When analyzing normal sections in the limit resistance state, the distribution and amplitude of unitary stresses on both concreteand reinforcements are determined on the basis of the following hypotheses:

- the plane sections that maintain their deformation characteristic both before and after the deformation (the hypothesis ofplane sections) (fig. 4)


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STAS 10107/0-9017

- the contribution of the concrete in taking over tensile stresses is insignificant;- theb b diagram is considered as indicated in fig. 1.x

In case of concrete elements, maximum specific deformation in the most compressed extreme fiber when

breaking the section blim has the following values (fig. 5, fig. 6, and the subclause 3.2.3)

- in case of eccentric compression, when hxx = 25.1 bi 0 (fig. 6, line 1):blim = bu

- in the conventional limit case of centric compression (fig. 6, line 2):blim = bu = 2

- in intermediary cases, when 20,


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STAS 10107/0-90 18

3.2.2 Definition and delimitation of bending to stress cases, with or without axial stresses, in connection with thelimit interaction curve Ncap = f(Mcap), are illustrated in fig. 7, for symmetric sections that have been symmetricallyreinforced.

3.2.3 In case of bent, eccentrically compressed and eccentrically elongated elements with high eccentriciy, asimplified calculation as shown in fig. 8 is admitted.

- unitaryary stresses on concrete in the compressed area are uniformly distributed on the x height of thisarea, and have theRc size. The relation betweenx and x (fig. 4 and 8) is as follows: (mathematical formula);

- the values0h

xbb = values corresponding to the balance point in fig. 7 (a = ap = Ra/Ea), can be taken

from table 12;

Table 12

Concrete class

< Bc 35 Bc 35Type of concrete Type of steel

b

OB 37 0.60 0.55Common concrete

PC 52, PC 60 STNB 0.55 0.50

OB 37 0.55 -Concrete made of light

aggregates PC 52, PC 60 STNB 0.50 -

Centric

Compression

Ncap

Compression

Ncap

Elongation

The limit

interaction curve

Ncap=f(Mcap)

(Balance

Point)

Pure

bending

Centric

elongation

Case II of eccentric

compression

(b

apa

>

0.8,a = -Ra(5 4) (16)

- in current cases, the influence of intermediary reinforcements Aai (Aa1 Aan) in determining the capablemoment of the section can be omitted. In case of elements for which this influence is significant and cannot be

neglected (pillars with big-sized sections, diaphragms etc.), unitary stresses ai in intermediary reinforcements aredetermined separately for each reinforcement, using the following relations:

! if 0.8

! > 0.8

The following condition shall be respected in dimensioning elements subjected to bent:

b

3.2.4 In case of structural elements, which are exposed to seismic stresses included in the a class according to thesubclause 1.2.5, a more restrictive condition than that in the subclause 3.2.3 is imposed for the potential plastic parts in

order to secure the necessary sectional ductility namely is: lim, where lim displays the following values:

- lim = 0.25 in the extremities of the frame rulers (the Aa reinforcements are also considered);- lim = 0.40 in the extremities of the pillars. This value can be exceeded until b provided that the

confinement transversal reinforcement is increased in accordance with the (197) relation and the subclause J.2.3 inAnnex J.

The verification on the basis oflim values is performed separately for each main direction of the section.

values, which compare to lim, result from the calculation resistances of the concrete and of Rc, Ra

reinforcements.

NOTES:1. Some other lim values than the prescribed ones can be admitted provided a clear argument is submitted, and theyresult from a detailed non-linear dynamic calculation.

2. In case of diaphragms, the lim values depending on the shape of the section are determined in accordance withtechnical regulations specific to diaphragm structures.


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STAS 10107/0-90 20

3.2.5 In case of eccentrically compressed linear elements, the e0 eccentricity of the N stress is increased with anadditional eccentricity ea, which takes into account the lack of homogeneity of the section and the execution tolerances,

and has the biggest of the following values:

20 mm orh/30

where h measures the side of the section in accordance with the direction of the e0 eccentricity.

NOTE: In fig. 7, for a given value of the axial stress N, the net (available) capable bending moment Mcap Nearesultsfrom the difference between the Mcap abscissa of the respective point located on the limit interaction curve and the Nea

abscissa of the respective point located on the OA line.

3.2.6 In case of eccentrically compressed elements, the slenderness influence (of II nd degree effects) is characterizedby the increasing coefficient of the bending moment, resulted from the following relation:

where

MIbending moment resulted from a Ist

degree calculation of the structure;

MII bending moment resulted from a IInd

degree calculation of the structure.

In case the subclause 3.1.2 ( 1.5) is observed, it is allowed to consider the EIrigidity modulus of the bars asbeing constant, irrespective of the stress, and having the following value in the II

nddegree calculation of the structure:

where

(EI)conv the conventional rigidity modulus of the transversal section, close to the limit resistance state,

including the effect of the reinforcements, of the resting phase of the concrete, and of its slow flowing

deformations;

Ib inertia moment of the concrete section;P total percentage of longitudinal reinforcement of the section;Mld I

stdegree calculation moment of bending, which result from pillar long term strains producing pillars

deformation by side displacements of the junction points;

MIst

degree calculation moment of bending resulted from the total load.

NOTE: In order to determine the values of the coefficient and to place them within the limits prescribed in the subclause

3.1.2, Ist degree and IInd degree analyses use the same values of the (EI)conv rigidity modulus.

In case of structures where 1.2, it is allowed to replace the IInd

degree calculation with the following

relation in order to approximately determine the values of the coefficient:

where

(EI)conv as indicated for the (19) relation;

lfl buckling length of the element, estimated depending on the nature of its connection with the rest of

the structure.

In case of structures with rigid junction points, the bending moments in the extremities of the rulers shall be

correlated with the bending moments in the extremities of the pillars increased by so that the equilibrium of themoments around the junction points would be maintained.


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STAS 10107/0-9021

In case of framed structures with fixed junction points or of structures which side displacements are limited

due to some rigid diaphragms that take over horizontal pressures, the increment of bending moments by applies onlyto the middle third part of the pillar height, on each level. Verifications in the middle third part of the height of each

level are not necessary in current situations, when the subclause 3.1.2 ( 1.5) is observed, and pillar reinforcement isconstant on the height of each level.

IInd

degree effects are neglected in the calculation ( 1) in case of elements whose slenderness coefficient 0

meets the following requirement:

where i is the radius of inertia of the transversal section on the considered direction.

In case of elements that display a rectangular section the above-mentioned requirement is as follows:

where h measures the side of the transversal section on the considered direction.

3.2.7 Dimensioning in the limit resistance state of eccentrically or centrically elongated elements, with a loweccentricity degree (theNstress appears between the Aa and A

a reinforcements), is performed considering that:

-

concrete does not take over stresses;- unitary stresses in Aa and Aa reinforcements equalRa.3.2.8 Provided that the simplifying procedures described in the subclause 3.2.3 are accepted, the calculation in thelimit resistance state of elements with one symmetric axis, exposed to bends with or without an axial stress, is

performed by means of the relations included in table 13.

Table 13

Naxial stress with the sign + for compression;Mbending moment

CGcentroid of the section

a according to the (17) and (18) relations, with the sign + for elongation stresses

Notations StressApplication

field Calculation relations

Bending

(current

situation,

with Aai = 0)

Eccentriccompressi

on and

eccentric

elongation

with a high

degree ofeccentricit

y

Eccentricelongation

with a low

degree of

eccentricit

y

Ab = x

yy db0

surface of prestressed concrete area

Sb = x

y dyyhb0

0 )( statical moment of

prestressed concrete area in relation with the centroid of

the Aa reinforcement

Resistance condition

where a is according with the (15) and (16) relations


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STAS 10107/0-90 22

3.2.9 Calculation relations provided in the subclauses 3.2.23.2.6 and in table 13 for eccentrically compressedelements also apply to band pillars with circular section. The effect of the hooped reinforcement is considered by

introducing an increased value in the calculation of calculation resistance of prestressed concrete:

fs volumetric coefficient of transversal reinforcement =

s

s

sd

A4;

As surface of the transversal section of the hooped reinforcement;

S step of the hoped reinforcementds diameter of the hooped concrete core;

Ras calculation resistance of the hooped reinforcement;

e0 = M/N

with the observance of the superior limit of the compression axial stress:

whereAbs =4

2

sdis the surface of the hooped concrete core.

3.2.10 The calculation in the limit resistance state for elements exposed to inclined bending, with or without axialstress, is performed by considering the hypotheses presented in the subclause 3.2.1. Equilibrium equations are

determined in accordance with the inclined position of the neuter axis.In current situations, it is allowed to perform a simplified calculation using the method presented in Annex B,

based on approximating the variation laws of the capable moment in accordance with the inclination angle of its plan.

NOTE: Other similar methods can be used, as well, provided they are based on parametric researches and a profoundcalculation.

3.3 Calculation in the limit resistance state in inclined sections

3.3.1 General3.3.1.1 Calculation resistance of inclined reinforcements (cross-ties, inclined bars) in the calculation of the cuttingforce results from the following relation:

Rat= matRa (25)

where matis the coefficient of work conditions, and has the following values:

mat= 0.8 for reinforcements made of rolled steel (PC 60; PC 52; OB 37);

mat= 0.7 for reinforcements made of drawn wires (STNB; STPB).

3.3.1.2 The stress level in case of cutting force is characterized by the following ratio:

where

Q the calculation cutting force;Ab0 the area of the useful cutting section of the element expose to a cutting force.

In case of rectangular or T-shaped sections:

Ab0= b h0

In case of sections where b varies with the height of the section, the value ofb is chosen from the neutral axis.

where


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STAS 10107/0-9023

3.3.1.3 The calculation of transversal reinforcements is not necessary if:75.0Q for plates;

50.0Q for the other types of elements. (27)These specifications are also considered in the calculation of the bearing capacity at cutting force of elements

that do not display transversal reinforcements.

3.3.1.4 Concrete sections of elements shall be dimensioned so that the limitation requirement of main compressionstresses is observed:

cQ (c 1 ) (28)As follows, values corresponding to c are provided for different types of elements and stresses.

3.3.1.5 In case of elements that are part of anti-seismic structures, which display potential plastic areas on one or bothextremities, or nearby these extremities, the calculation cutting force Q is associated with the diagram of moments withcapable moments in critical cutting sections (where the reinforcement flow is initiated).

3.3.2 The cross force calculation in the inclined sections of elements exposed to bending (beams, plates withcontinuous propping)

3.3.2.1 In case of a section along an inclined fissure, having its position and inclination determined (fig. 9),verifications are usually performed at the maximum value of the cross force along the entire fissure. If the decrease of

the cutting force on thesi length due to the loads exerted on this length is considered in the calculation, the gsi reduction

caused by permanent stresses is taken into account, instead of the qsireduction given by the total stress g.

3.3.2.2 In case of frame rulers, which are included in the category described in the subclause 3.3.1.5, the passing onmechanism which is considered in determining the calculation cutting force is represented by capable moments of

opposite signs, in the two extremities of the opening.

3.3.2.3 Calculation elongation resistance of the concrete Rt depends on the coefficient of work conditions mt asdescribed below, in order to take into account the effect the stresses exerted on the extremities of the beams have upon

the involvement of the concrete in taking over the cross force:

Rt red. = mtRt (29)

where

- in potential plastic areas with ,1Q 1

2

3

Qmt (30)

- in the rest of the cases, mt= 1.- In case of beams that display a stress level Q >1 at alternative cutting forces in both directions, mt= 0(e.g: rulers for hollowed diaphragm coupling).


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STAS 10107/0-90 24

3.3.2.4 For beams, in the general relation (28):c = 2 in case of potential plastic areas (31);

c = 4 in the rest of the cases (32).

NOTE: In (31) and (32) relations, Q is determined by means of the (26) formula, where mtis not affected byRt.

3.3.2.5 Cutting force calculation of elements with a constant section is performed by means of the following relation:where (fig. 10)

Q calculation cutting force determined in accordance with the subclauses 3.3.2.1 and 3.3.2.2;

Qb cutting force, which has been taken over by the concrete in compressed areas, and results from the

following relation:

p=

0

100

bh

Aapercentage of longitudinal reinforcement in the plane area, along the inclined fissure;

Aai aria of the section of an inclined reinforcement, cuttinged by the inclined fissure;

Ac aria of the transversal section of a cutting-tie arm, cuttinged by the inclined fissure;

nc number of cutting-tie arms;

ndsi according to fig. 10.

The Aai includes only those inclined reinforcements that are crossed by the fissure on the central area, equalto of the total length of the inclined area.

(33) relation is verified for the most unfavorable inclination of the fissure, which is determined by

conditioning Qcap to have a minimum value, within the following limits:

0.5 h0si 2.5 h0 (35)

For elements without inclined bars, the requirement for is minimum Qcapvalue is reduced to:

Qcb = Qb + ncAcRat= minimum (36)

In current situations, it is allowed to define the most unfavorable fissure of elements with inclined bars in a

simplified manner as well, conditioning Qcb , and not Qcap, to have a minimum value.

3.3.2.6 In case of elements with a variable section, the calculation cutting force Q, determined as shown in thesubclause 3.3.2.5, is corrected with the Mtg/z term, where:

M,z calculation bending moment and the lever arm of internal stresses in the analyzed section;

angle formed by the directions of the two bottom foundations in the area with variable section.


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STAS 10107/0-9025

The M tg/z term either diminishes the calculation cutting force Q or increases it depending on whether thesection of the element increases in the same direction or in the opposite direction than the binding moment (fig. 11).

3.3.2.7 In case of coupling the rulers for diaphragms with voids coupling, to which potential plastic areas apply underseismic stresses, the fissure inclination is considered to be of 45

o, and the involvement of the concrete in taking over the

cutting force is neglected (Qb = 0).

In case of less stressed coupling rulers, which do not display any potential plastic areas in the extremities, the

cutting force verifications in inclined section is performed as described in the subclause 3.3.2.5.

In the cutting force calculation of coupling rulers, specific technical regulations for structures with diaphragms

shall also be considered (special provision for high rulers, correlation between capable moment and cutting force etc.)

3.3.3 Bending moment calculation in inclined sections exposed to bending (beams, plates with continuous propping)The bending moment calculation is performed considering the hypotheses presented in the subclause 3.2.1, and

verification the equilibrium relation between the moments and the compressed area centroid, where a = Ra in case oftransversal reinforcements:

MAaRaz+ AatRazt+ ne AeRaze (37)

where

M calculation bending moment in the end of the section of the fissure compressed area;

Aat,Ae according to the subclause 3.3.2.5;

z,zt,ze according to fig. 12.

Verifications by means of the (37) relation are not necessary if the subclause 6.5.2.7 concerning the

determiantion of sections where plane reinforcements can be interrupted or raised (lowered) is observed.


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STAS 10107/0-90 26

3.3.4 Cutting force calculation in the inclined sections of eccentrically compressed elements3.3.4.1 In case of pillars that are part of anti-seismic structures, and one of their extremities display a potential plasticarea, the cutting force calculation is performed accordingly, with the capable moment in the respective extremity, and

the corresponding moment in the opposite extremity. The latter can be determined in a simplified manner, increasing

the moment from the calculation seismic stresses by adding the ratio value between the capable moment and that ofcalculation stresses in the extremity of the plastic area.

In current situations, when it comes to the pillars of storied frames, it is allowed, for simplifying purposes, to

determine the cutting force by means of opposite capable moments at both extremities.

The cutting force Q determined in this way shall range between the following limits:

1.5QsQ

sQ(38)

where

Qs cutting force, resulted from the statical calculation with conventional seismic stresses (calculation),established in accordance with specific technical regulations concerning the anti-seismic designing of

constructions;

reduction coefficient of the effects of seismic stresses, which takes into consideration the ductility ofthe structure.

If a detailed non-linear dynamic calculation of the structure confirms that no potential plastic area appears at

neither of the extremities of the element, the calculation cutting force (Q) is determined as above, and the (38) relation

is reduced to Q 1.5Qs (the superior limit is not necessary anymore).

3.3.4.2 The calculation of the pillars is performed by means of the same relations as in the case of bent elements (thesubclause 3.3.2); the influence of compressing axial stress upon the cutting force is also considered by introducing the

following in the (29) relation:

mt = 1 +0.5n (39)

where

n =cRbh

N

0

Naxial effort, in the loading hypothesis which has determined the cutting force.

In case of pillars, in the (28) relation:

c = 2 (40)

NOTE: In the (40) relation, the mtcoefficient provided in the (39) relation doesnot influenceRt.

3.3.4.3 The following simplifications are permitted in the cutting force calculation of continuous vertical diaphragmsand of hallowed diaphragm braces in inclined sections:

- the fissure inclination is considered to have 45o;- the cutting over transferred to the concrete is Qb = 0.5 bhRtin the potential plastic area at the bottom of

the diaphragm, and Qb = 0.7 bhRt in the rest of the height.The general (28) relation applies as follows Qb1.5 bhRt , considering as well the limitations prescribed by

the (38) relation.

In order to establish the cutting force related to the breaking moment in case of continuous vertical diaphragms

and of hallowed diaphragm braces, specific technical regulations with respect to structures with diaphragms shall also

be considered.

3.3.5 Cutting force calculation of the junction points of frames on levelsThe calculation is performed in accordance with specific technical regulations for structures with frames on

levels made of reinforced concrete.


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STAS 10107/0-9027

3.3.6 Cutting force calculation of eccentrically elongated elementsCutting force calculation is performed by means of the same relations as in case of bent elements (the

subclause 3.2.2); the influence of elongation axial stress upon the cutting force is also considered by introducing the

following in the (29) relation:

- for eccentrically elongated elements with a high eccentricity degree:

where

0 = e0/h (42)

- for eccentrically elongated elements with a low eccentricity degree:mt= 0

3.3.7 Short lugs (lch according to fig. 13)3.3.7.1 In case of short lugs, in the (28) relation the following is considered:

c = 2

In case of short lugs that prop rolling cantilevers, when overhead cranes are exposed to difficult or severe

operations (group IIIV as prescribed in STAS 10101/2A2-78), the following requirement shall be respected as well:

whereQ1 maximum cutting force resulted from verifications in the limit fatigue state, increased by a coefficient of

1.5.

3.3.7.2 2/3 of the horizontal cuttingties placed along the height of a short lug are considered active in the calculation.The total surfaceAa0of the sections of these cuttingties shall meet the following requirement:

3.3.7.3 In case of lugs that display a medium length (1 lc / h < 1.5), the calculation is performed as for both a short orlong lug, and the most unfavorable hypothesis is considered.


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STAS 10107/0-90 28

3.3.8 Piercing calculation of plates with local propping (on pillars)3.3.8.1 These specifications refer to the piercing calculation of plates propped on pillars only if the stress that the plate

passes on to the pillar is centric (centric piercing).

In case the joints between the slabs and the pillars do not transmit significant binding moments (examples: raft

foundations, plates of civil buildings on levels with a net load of maximum 3000 N/m2

, whose horizontal forces aretaken over by diaphragms), it is allowed to consider the load passed on from plates to internal pillars as being centric. In

case of side or corner pillars deprived of perimetric beams, and generally speaking, in case of the plate-pillar bond

transmits significant binding moments, the piercing calculation, influenced by both vertical load and binding moment, is

performed in accordance with specific technical regulations concerning slab plates.

3.3.8.2 Centric piercing verification is performed in accordance with the design in fig. 14; the active piercing sectionis formed by the conjunction of 45

oplanes, raised from the outline of the pillar section, with the median plane of the

plate. The perimeter of the active section results from the following relation:

Ucr= 2(a + b + 2hp)

In case of pillars with a circular section of diameterd:

Ucr= (d + hp)

3.3.8.3 In case of plates without transversal reinforcements in pillars propping areas, verification is performed bymeans of the following relation:

Q 0.75Ucrh0Rt(46)

where

Q calculation piercing force;

h0 net height of the plate.


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STAS 10107/0-9029

3.3.8.4 In case of plates with transversal reinforcements in propping areas, verification is performed by means of thefollowing relation:

Q 0.50Ucrh0Rt+ AavRat+ AaiRatsin 1.2Ucrh0Rt (47)

where

Aav sum of the surfaces of all sections of those vertical reinforcements that cutting the theoretical piercingsurface (the inclined sides of the frustrum of a tetrahedron, as shown in fig. 14);

Aai sum of the surfaces of all sections of those inclined reinforcements, which form a angle with theplane of the plate, and cutting the theoretical piercing surface.

3.3.8.5 In case of very thick plates, as those of raft foundations, whose piercing active surface depends on its totalsurface, it is recommended to consider in the calculation of the piercing force that stresses exerted on this surface can be

deducted from the total stress the plate passes on.

3.3.8.6 Technical regulations with respect to reinforced concrete surface foundations shall also be considered in thepiercing calculation of the isolated foundations of the pillars.

3.4 Special verification cases for transversal reinforcements

3.4.1 Cutting-tie as suspension reinforcements3.4.1.1 In case of platform beams, with the plate propped at the level of the bottom of foundation (reversed beams),cutting-tie dimensioning shall also consider the elongation stresses exerted on them so that they would be able to

transfer stresses from the plate to the upper part of the foundation.

3.4.1.2 In case of level cutting between secondary and primary beams, both monolithic or precast (fig. 16), theprimary beam shall be provided with additionally dimensioned cutting-ties in centric elongation, at the lengths = 3b + 2

h, in order to eliminate the concentrated load passed on by the secondary beam.

3.4.1.3 In case of elements exposed to bending, with or without axial stress, which display indentation angles in theelongated area of the section (fig. 17):

- if reinforcements in elongated areas cutting the indentation angles and go further on in the prestressed areaof the section, with an anchorage length determined as described in the subclause 6.2 and measured from h/2 as shownin fig. 17 a, it is not necessary to perform an calculation of cutting-ties as suspension reinforcements, constructively

displayed;

- when indentation angles meet the following requirement tg 0.05, as shown in fig. 17 b, it is allowed tobuild the elongated reinforcement over the indentation angle; under these circumstances, the changing direction area of

longitudinal reinforcements is provided with supplementary cutting-ties, elongated for the resultant R = 2AaRasin /2 ofall stresses within longitudinal reinforcements. In situations as such, intermediary cutting-ties are provided so that each

longitudinal bar to be dangled from the corner of a cutting-tie.

Primary

beam

Secondary

beam


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STAS 10107/0-9031

3.4.2.4 Coupling elements are distributed as uniformly as possible along the sliding surface, and they are anchored onboth extremities as elongated bars stressed up to the calculation resistance level.

3.4.2.5 When the potential sliding surface is perpendicular on the axis of the element (example: horizontal cast joints of

vertical monolithic diaphragms at the level of the plates), according to fig. 18a, dimensioning of coupling elements

results from the following relation:

Q Lcap (49)where

Q calculation cutting force in the analyzed section of the element, andLcap is determined from the (48) relation,

with the following specifications:

- for elements which are part of anti-seismic structures, in seismic calculation areas from A to E, and Nisa compression stress, its amplitude is multiplied by 0.6;

- Aac includes the surfaces of the sections of vertical reinforcements, located in the core and in theextremities of the elongated end of the section.

3.4.2.6 In case the potential sliding surface is perpendicular to the axis of the element (examples: precast overconcrete

elements), the dimensioning of the coupling elements results from the following relation:

L Lcap (50)where

L calculation sliding force, similar in this case with resistance capacity of the element (for instance, if thesliding surface is located in the stressed area of the section, L is associated with the capacity of the stressed

reinforcement: L=AaRa), and Lcap is determined by means of the (48) relation, forN = 0 and with the

following specifications (fig. 18 b):

a) for coupling elements located in the area with negative moment L=Aa (propping)Ra, which is uniformlydistributed along the length l0=lof the diagram of negative moments, determined in the load hypothesis which produces

the maximum moment at the extremity of the respective bar;

b) for coupling elements located in the area with positive moment L=Aa (propping)Ra, which is uniformlydistributed along the length l0=lof the diagram of moments from the section that displays a maximum positive moment

as far as the section that annuls the positive moment, both determined in the load hypothesis which produces themaximum moment on the respective plane. In case of elements with simple propping, lc=1/2;

c) in the potential plastic areas of frame rulers that are part of anti-seismic structures, in seismic calculationareas from A to E:

- if plasticity is a consequence of negative moments (which exert elongation stresses on reinforcementswithin overconcreting), beams with medium = L/blr>2Rt may have at least 30% of the poise weights within theoverconcreting welded to inclined bars of the same diameter, which come out from the precast part of the beam. Therest of the sliding force can be passed on by means of vertical cutting-ties, uniformly disposed on the length lr;

- if plasticity is a consequence of positive moments, it is allowed to perform the coupling barely by meansof cutting-ties.

Coupling elements


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STAS 10107/0-90 32

3.4.2.7 The calculation of pedal plates is performed in accordance with specific technical regulations with respect tothis type of plates.

3.5 The calculation of elements in the limit resistance state exposed to twisty bending stresses

3.5.1. In case of elements exposed to wrapped bending stresses, the stress level of shear stress is characterized by the following ratio:

where

Q, Ab0 according to the subclause 3.3.1.2

Mt calculation twisting moment;

Wt modulus of twisting resistance, determined as in the case of an ideally plastic section. In case of

rectangular sections Wt= 1/6 b2h(3-b/h), where b is the small side, and h is the big side, irrespective of

their direction.

3.5.2 The calculation of supplementary longitudinal and transversal reinforcements essential in taking over the twisting moment isnot necessary if (symbol).

3.5.3 The concrete sections of the elements shall be properly dimensioned so that (symbol), which results from the (51) relation, toobserve the following condition:

cQ where

c is determined as described in the subclause 3.3.2.4.

In case of frame rulers, which are included in the category described in the subclause 3.3.1.5, the cutting force calculation andthe practical application of the (51) relation are performed in accordance with the subclauses 3.3.2.23.3.2.5.

3.5.4 In case 0.5 < cQ (where c is according to the 3.3.2.4 provision), the reinforcement calculation in order for them to takeover the stresses generated byMt, and their summing up with those reinforcements that take over cutting forces are performed as follows:

- the necessary quantity of transversal reinforcement for taking over cutting forces is determined from the relationspresented in the 3.3.2 provision;

- the supplementary quantity of cutting-ties to take over twisting moments results from the following relation:

where

Ae surface of the section of a cutting-tie arm;

ae distance between cutting-ties;

Abs surface of the section of the concrete core, bordered by the internal sides of the perimetric cutting-ties.

The diameter of the cutting-ties and the distance between cutting-ties are settled by summing up the necessaryquantity of transversal reinforcement, resulted from both cutting force calculation and twisting moment. In case of wide

beams, whose cutting-ties display more than two vertical arms, the addition is performed barely for perimetric cutting-

ties; the internal cutting-ties are considered only in the cutting force calculation;

- the supplementary quantity of longitudinal reinforcement for taking over twisting moments is determined using thefollowing relation:

where

Aat sum of the areas of supplementary longitudinal reinforcements, disposed on the perimeter of the section;

Us perimeter of the concrete core, which has the areaAbs.


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STAS 10107/0-9033

For tube or box shaped section elements (fig. 19), Abs and Us are calculated as for complete section with the

same external contour.

NOTE The calculation relations assume as provided the requirement of cutting nondeformability for element section, bysufficient thickness of cores and of bottom foundations or, if necessary, by providing cutting stiffening

diaphragms.

3.5.5 In the case of elements with section made of more rectangles (for example T-shaped or double-T-shapedsection), the moment of torsion is distributed to the rectangles component proportionally with their moments of inertiaat torsion, calculated as for homogeneous and elastic elements.

3.6 Calculation of unitary stress in concrete and in reinforcement in II stage of work, for elements exposedto bending with or without axial stress

3.6.1 The determination of unitary stress in concrete or reinforcement in II stage of work is done in the cases whenverifications are performed for limit opening states of cracks, of deformation or fatigue.

3.6.2 The calculation of normal unitary stress in II stage of work is done by admitting the following hypotheses:

- plane sections before deformation remain plane also after deformation;

- the contribution of concrete is neglected when taking over the tensile stress;

- for concrete or for reinforcements, the relations between unitary stresses and specific deformations are linear.

In calculation relations, the elasticity modulus of concrete is introduced with corrected value:

- for concrete with standard aggregates:

- for concrete with simple aggregates:

where

v proportion between bending moment from long time exploitation loads and the one from total

exploitation loads;

deformation characteristic of concrete in time.

An equivalent (ideal) concrete section is considered in calculation, where the reinforcement quantities Aa, Aa

interfere multiplied with the equivalence coefficient


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STAS 10107/0-90 34

3.6.3 General relations for the calculation of normal unitary stress in concrete and in reinforcements a, a (fig.20):

3.6.3.1 In the case of elements stressed during bending (ME

bending moment from exploitation loads):

- the position of neutral axis is determined with the relation:

)()()1( 0'' xhAnaxAnS aeaebe =+ (57)

where Sbc = x

0

byy dy static moment of concrete compressed area in comparison to the neutral axis;

- the moment of inertia of ideal concrete section is determined with the relation:2

0

2'' )()()1( xhAnaxAnII aeaebebi ++= (58)

where Ibc = x

0

byy2dy moment of inertia of the concrete compressed area in comparison to the neutral axis;

- normal unitary stress in concrete and in reinforcements is determined with the relations:

3.6.3.2 In general, in the case of elements stressed during bending with axial stress, using the same notations as theones from sub-close 3.6.3.1, the unitary stress in concrete and in reinforcement are obtained by using the relations (60)

and the relations:

where the sign plus corresponds to the compression stress.

3.6.4 The main unitary tensile stress at the neutral axis level is calculated with the relation:

where

b width of the section core;z lever arm of the inner stress calculated in the II stage of work and which can be taken in a simplified

way z ~ 0.85 ho.

For the elements with variable section, the cutting force of calculation from relation (62) is corrected with the

term M tg /z, in the same mode as at subclause 3.3.2.6.


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STAS 10107/0-9035

3.7 Verification at the fatigue limit state

3.7.1 The verifications of reinforced concrete elements, to which the stresses may lead to the appearance of thefatigue phenomenon, is done with the condition that:

- normal unitary stresses in concrete and in reinforcement in II stage of work, determined according to

subclause 3.6.3, do not surpass the calculation resistances to fatigue established according to subclauses 2.1.2.2;2.1.2.4.3 and 2.2.1.3;

- main unitary tensile stresses, determined according to sub-close 3.6.4, should be taken over by concrete andreinforcements.

The unitary stresses are determined for the group of loads appropriate to limit state of fatigue except the loads

given by machines and equipment with fixed location for which are taken in consideration the calculation loads

appropriate to the verifications at resistance limit state.

3.7.2 The stress level to main tensile stress for elements with rectangular section or T-shaped is characterized by theproportion:

where 1 is calculated with the relation (62).The calculation of cutting reinforcements is not necessary if1 0.50.

The concrete sections of elements should be proportioned in such a way that the limitation requirement of maincompression stresses should be respected:

21

The main tensile stresses 1 are taken over as follows (fig. 21):

- In the area 1 < 0.50, are taken over by concrete;- In the area 0.5 1 2:a) if the loads are not alternating (the asymmetry coefficient = bmin / b max0) the stresses 1 are taken over

by concrete and cutting reinforcements (clamps and inclined elements or only clamps), the part taken by concrete being

1 = 0.3

b) if the loads are alternating ( < 0),

stas 10107-0-90 civil and industrial constructions (en)

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