p85-96

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INDICATIV P85-96

REINFORCED CONCRETE STRUCTURAL WALLS

A). CALCULUS OF THE TRUCTURAL WALLS

SECTIONS

1. Plasti !"#$s

There are considered plastic zones of the structural walls the following situations:

for the coupling beams, the whole span;

for the structural walls (isolated or coupled), the zone having the length lp measured

from their base:

lp= 0.h ! 0.0"#

$n the case of multistor% buildings, this dimension is upward averaged to a whole number of

stories, if the limit of the plastic zone e&ceeds the height of a level with more than 0.'# level. $f not, it

is downward averaged to a whole number of stories.The zone from the base of the wall limited in this wa% is called one .

The rest of the wall, less loaded and with reduced design demands compared with zone , is

called one *.

%. T&$ 'i($#si"#i# *al+$s ", t&$ s$ti"#al $,,"ts.

%.1. T&$ 'i($#si"#i# *al+$s ", t&$ /$#'i# ("($#ts

The values are determined with relations from the figure:

1 2 3

M 1 M 1

M c1

M 2 M 2

M c2

M 3

M 3 M c 3

M < 0.2Mrmax

M < 0.3M

a)

b)

a) In over structure (above the infrastructure or foundation):+ = ++s+s,ob) In infrastructure:

+ = -,"+s

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QS

Mcap,min

MS

M M M s

M S0

QS

QM Q

s

Q S0

KM

1.25

1.0

1.5

KQ

where:

+s= bending moment from the design seismic loading; at the basement level has the value +s, o;

= ........... between the overturning moments;

+o, cap= computed at the basement level of the structure, associated to the strength capacit% of the

structural wall, cantilevered or coupled, and the value of the overturning moment;

+o= from the design seismic loading (see the figure):

+

./+

o

iicapi,

+=

QS,0

H 0 H 0

L1

L2

M1,cap

M2,cap

M3,cap

QS,0

Mcap,o

M0

=QS,0

H0

a) b)

+i,cap= the capable moment at the base of cantilever wall i;

/i= the a&ial effort at the base of the cantilever wall i, produced b% the horizontal forces, in thecase of the plastification of the coupling beams e&tremities;

i= the distance from the a&is of the cantilever wall i to the reference point with respect to whom

the moments are computed;

+= correction coefficient of the walls bending efforts.

%.%. T&$ 'i($#si"#i# *al+$s 0 ", t&$ s&$a ,"$s

$n the case of the structures for which the seismic forces are taen over in totalit% b% the

structural walls, the value of 1 is determined with the relation:

-,"1s1 = 11s 11swhere:

1s= the shear force from the design seismic loading;

1= correction coefficient of the shear forces:

-,' 1= - ! 0,02n -,"

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inf

cap

sup

cap +,+

n = the number of stories

%.. T&$ *al+$ ", t&$ '$si# s&$a ,"$ ," t&$ "+2li# /$a(s

$t is determined with:

r

inf

cap

sup

cap

l

++1

+

=

where:=the absolute values of the capable moments in the sections at the e&tremities of

the coupling beams, from both senses of action of the moments, established on the

base of the design strength 3aof the reinforcement; for the value of + capsup, the reinforcement

contribution inthe active zone of the floor will be taen into consideration;

lr= lo= the span of the coupling beam.

%.3. T&$ 'i($#si"#i# a4ial ,"$s ,"( t&$ "+2li# alls

The dimensioning a&ial forces from the coupling beams are estabished on the base of the

wall e4uilibrium in the situation of plastified coupling beams, but without the '"5 increased value

of the bending strength capacit% ,considered in the above relation.

. T&$ "(2+tati"# ", t&$ l"#it+'i#al a#' ta#s*$sal $i#,"$($#t

", t&$ st+t+al alls

.1. T&$ "(2+tati"# ", t&$ l"#it+'i#al $i#,"$($#t

The computation of eccentrical compression (tension) of the structural walls is made

according to the prescriptions from the 6T6 -0-078090 code.

.%. T&$ "(2+tati"# ", t&$ st+t+al alls ," t&$ s&$a ,"$

The computation for the shear force is made in inclined sections and horizontal sections at

the casting level.

a) The computation in inclined sections

$n the case of the structural walls with the ratio between the elevation height and the section

height #8h -, the dimensioning of horizontal reinforcement a ofor the shear force in inclined

sections is based on relation:

1 1b! 0,< ao3awhere:

a o= the sum of the horizontal reinforcement sections intersected b% a "oinclined crac, including

the belt beams reinforcement and the continuous reinforcement from the active zone of the floor

(include three floor heights on both sides of wall), if the crac crosses the floor;

1b= the shear force taen over b% the concrete, with the values:

1b= 0,2bho0,bh3t for the zone of the wall;

1b= bh(0,73t! 0,'"o) for the zone * of the wall.

>?= the average compression stress in wall section. @hen >? is tension, is taen with minus sign in

zone * and zero in zone .

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x > 5b

> 0.4h

h

a)

H

15>

H 15

>

4h

p

4h

p

hp

x > 2hp

b

b)

b) The computation in horizontal sections at casting levels.

The dimensioning is made according to the prescriptions from the 6T6 -0-078090 code.

3. T&$ "(2+tati"# ", t&$ $i#,"$($#t ,"( t&$ "+2li# /$a(s

The computation of the longitudinal reinforcement is made according to the prescriptions

from the 6T6 -0-07809 0 code.

3.1. C"+2li# /$a(s $i#,"$' it& &"i!"#tal /as i# sti+2s

The transversal reinforcing is determined from condition that these ones have to tae over

the whole design shear force, according to relation:

( ) rae

eae

h0,

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3.%. C"+2li# /$a(s $i#,"$' it& i#li#$' /as

The area aiof the inclined reinforcement on each diagonal is determined with the relation:

sinA'3

1)

a

ai =

where A = the inclination angle of reinforcement.

) CONSTRUCTIVE RE0UIREENTS

1. T&$ all $i#,"i#. 7$#$al 2"*isi"#s

1.1. T&$ $i#,"$($#t "*$la22i#

a) $t is recommended that the vertical reinforcement to be realized without hoos.

b) Bor the reinforcement with independent bars, in the potential plastic zone (zone ), the

minimum overlapping lengths are given in the table.

3einforcement +inimum overlapping lengths for bars from:C* 27 DE "', DE 0

#orizontal bars, including those from the belt beams and the vertical bars from the

web reinforcement.

@ithout hoos: 70d"0d

@ith hoos: "0d

6tructural vertical bars with a situated at the e&tremities

$n the same section it is

overlapped "05 or less

than the total

reinforcement area.

*ars with d F '0 mm

@ithout hoos: 70d"0d

@ith hoos: "0d

+inimum 00 mm*ars with d '0 mm are over lapped b% welding

$n the same section it is

overlapped more than "05

of the total reinforcement

area.

*ars with d F - mm

@ithout hoos: 70d0d

@ith hoos: "0d

*ars with d - mm are over lapped b% welding

Bor the zone * the minimum overlapping lengths are with -0d less than those from the table.

lso, in the zone * it is not necessar% the overlapping b% welding of the reinforcement with d

-('0) mm.

1.%. T&$ $i#,"$($#t a#&"a$

a) Horizontal bars from the belt beams and the horizontal independent bars from the field

reinforcement at intersections in T or L shapes.

!

> 40! "#52, "#$0 %&3' (ih hoo*s

> $0! %&3' (iho+ hoo*s

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*ars with..........: la= 0d (C* 27, DE "', DE0)

*ars without.........: la= 0d (DE "', DE0)

la= 0d (C* 27)

b) Horizontal bars from the coupling beams. ccording 6T6 -0-078090

c) Vertical bars from walls anchored in foundations. ccording to 6T6 -0-078090

> 50! "#52, "#$0

%&3' (ih hoo*s

d) Vertical boarding bars of the openings which are anchored in a wall at an inferior level.

lawill be determined such that to contain a corresponding number of vertical bars from the current

reinforcement of the inferior wall, but minimum '.00 m.

The mesh, which form the continuous reinforcement of the walls, will be connected with

hoos in order to insure their position during the concreting.

Gsuall%, there will be at least:

hoos8m'for bars with d H < mm;

hoos8m'for bars with d < mm.

%. Fi$l' $i#,"$($#t ", t&$ st+t+al alls

%.1. T&$ st$#t& $i#,"$($#t

$t is stipulated in the following cases:

in zone

in zone *, when 1 1b;

in short walls (#8h H -)

$n zone , regardless the t%pe of wall, the minimum reinforcement percentages are thosefrom the table.

Cutside the wall , the minimum reinforcement values for zone B will be adopted.

The calculus

seismic zone

+inimum reinforcement percentage for

#orizontal bars Iertical *ars

C*27 DE"', DE0 C*27 DE"', DE0

,*,E,J,K 0.205 0.'"5 0.'"5 0.'05

B 0.'"5 0.'05 0.'05 0.-"5

The minimum diameter:

mm for horizontal reinforcement < mm for vertical reinforcement

The ma&imum distance:

2"0 mm on horizontal direction

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'"0 mm on vertical direction

%.%. T&$ "#st+ti*$ $i#,"$($#t

$t is realized from two nets L" at '00 mm, from 6T/*, one at each part of the wall, or with

other steel reinforcement having e4uivalent diameters.

Bor the wall core around the stairs, on the whole length, and for the last level in all cases,

horizontal reinforcement will be added having the following minimum percentage: 0.'"5 for C* 27

0.'0 for DE "' or DE 0

. L"al $i#,"$($#t ", t&$ *$tial $l$($#ts

.1. T&$ $i#,"$($#t ", t&$ !"#$s ,"( t&$ st+t+al alls $4t$(iti$s

$n the zones from the structural walls e&tremities, on the surfaces indicated in the figure-,

for lamellar sections, in the figure ', for sections having boundar% elements, and in figure 2 for

coupled walls sections, the reinforcement is realized with cages of the same t%pe as those used for

columns.

opnin

b1

3 b

0.1

h2h

2

0.1

h2

0.1

h1

0.1

h1 h

1

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b1

3 b

0.1

h

0.1

h1 h

b1

3 b

0.1

h

0.1

h1 h

The minimum vertical reinforcement percentage of this zones reported to their area are

showed in the table:

The calculus

seismic zone

+inimum reinforcement percentage

C* 27 DE "'

zone zone * zone zone *

, *, E, J, K 0.5 0."5 0."5 0.5

B 0.5 0.5

The local reinforcement will have to obe%, from the point of view of distribution and the

minimum number of bars, the details from the figure:

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sirr+p

b

s)irr+p

o-rappin,

n,)h

0.1

h

a) (!! msh rin/orcmn

sirr+p

b

s)irr+p

b) rin/orcmn (ih in!pn!n bars

o-rappin nh

3b

o-rappin nh

sirr+p

s)irr+p


0.1

h

b) rin/orcmn (ih in!pn!n bars

3b

sirr+p

s)irr+p

The concentrated reinforcement together with the vertical reinforcement situated in the web

and the flange of the walls, including that in the intermediar% intersections, have to insure the wall

section a superior bending strength capacit% compared to the cracing moment + fof the section,

determined with:

+f= /rs! 0." cpl@f3twhere:

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rs= distance from the center of gravit% of the section to limit of the central core, situated on the

same part with the eccentricall% force /;

@f = the cracing resistance modulus of the section, computed considering the tension zone

completel% plastificated;

cpl= coefficient which taes into consideration the partial plastification of the tensioned zone of the

section; see table -", 6T6 -0-078090.

Stirrups

+inimum diameter: L mm and d8 (d = the minimum diameter of the vertical bars of the

areinforcement).

+a&imum distances:

zone :

-'" mm, but no more than -0d, for design seismic zones 9 K;

-"0 mm in design seismic zone B;

zone *: 9 '00 mm, but no more than -"d.

The stirrups of the cage will be made such that their area have at least the same strength

capacit% as the horizontal reinforcement from the adMacent fields. $n the case when this

reinforcement is interrupted in the cage, it is properl% overlapped with the cage stirrups.

.%. T&$ "#,i#i# $i#,"$($#t i# t&$ "(2$ss$' !"#$s

$f the height of the compressed zone of the sections, when the strength capacit% is reached,

is higher than the limit value (& &lim), a special confining reinforcement in the compressed zone

will be realized on a length of at least &8'.

The confining reinforcement 4uantit% a o, in each direction is computed with relation:

+=

h

&0,"

3

3c0,-0a)

a

c

eoa

where:

ae= a&ial distance between sets of confining stirrups;

c = dimension of the central core between the confining stirrups, measured perpendicular to the

stirrups braces;

lso, in the a oreinforcement can be considered the horizontal reinforcement of the web, if

this one is bent after the vertical bars and properl% anchored.

$n the zones where the longitudinal reinforcement percentage taes over the value '83a(/8mm'), supplementar% measures will be taen such that to avoid bucling of the bars situated in

the potential plastic zone. The confining reinforcement a ocan have this role. $n these zones it is

recommended that the transversal connection b% stirrups and hoos of the vertical bars with

diameter d - mm to be done with a ma&imum distance of d.

.. T&$ $i#,"$($#t ", st+t+al alls i#t$s$ti"#s

The interior intersections are reinforced with cages with ' crossed stirrups, which mae the

connection with the horizontal reinforcement of the walls.

The ma&imum distance between the stirrups: '00 mm.

The minimum vertical reinforcement of the intersection zones: L-' < L-0.

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s)irr+p

3b

min2

10

min 2 10

sirr+p

3b

min 2 10

min2

10

min 4 12


b) rin/orcmn (ih in!pn!n

bars

min2

10

min 2 10

min 2 10

min2

10

min 4 12

3b

.3. T&$ $i#,"$($#t a"+#' t&$ "2$#i#s

round openings with small dimensions reported to the wall dimensions, and which do not

influence significantl% the general ensemble behavior, a constructive reinforcement will be realized

on each side with at least two bars L-0 mm and having the section e4uivalent to the reinforcement

interrupted b% the opening.

.5. T&$ $i#,"$($#t ", t&$ alls a#' ,l""s i#t$s$ti"#s

belt reinforcement having at least four bars will be made along the width of the wall.+inimum diameter of the bars: -0 mm.

3. T&$ $i#,"$($#t ", t&$ "+2li# /$a(s

3.1. T&$ $i#,"$($#t it& l"#it+'i#al /as a#' *$tial sti+2s

a) The longitudinal bars resulted from the bending moment dimensioning placed at the

superior and inferior part of the section

+inimum diameter of bars: L-0 mm.

3ecommended steel t%pes: DE "', DE 0.

b) Intermediar! longitudinal bars placed on lateral sides

+inimum diameter of bars: L< mm.

+inimum reinforcement percentage reported to the bhrsection:

0.'05 for seismic zones 9 K;

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0.-'5 for seismic zone B

c) Vertical stirrups

+inimum diameter of bars: L mm.

+inimum transversal reinforcement percentage: 0.'05

+a&imum distance between stirrups: ae

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a

a a$0

!

$0

!

a a

b

> $0!

!

> 50!1

!1

p85-96

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