Note: Descriptions are shown in the official language in which they were submitted.
~ lO~SOZ3
nACKGR~I!N~ OF TT~ INV~NTION
FIELD OF THE INVEM~ION
The present lnventlon relates to a new and improved
metalllc mold element ror concrete to be used for the formation
of vertical ~oints ln the constructlon of underground structure
known as "dlaphragm wall" or "slurry wall".
The diaphragm wall or slurry wall ls a concrete wall
cast into the soll to a varlable depth, varylng ln wldth and
wlth a plan layout varlable according to the pro~ect requlrements.
The method of construction of sald dlaphragm wall is
to proceed with excavating and then castlng concrete by limited
lengths of wall. Inltlally a vertical trench of the width cor-
respondlng to the wldth of the wall, of a length at the order of
3 to 6 m, is excavated by means of a clamshell or other suitable
trenching equlpment, to the total depth designed for the wall7
The trench thus being dug ls being kept fil~ed with
bentonite slurry having the function of supporting the side walls
of the trench, such as to avoid a cave-in of the said side walls.
~ hen excavation of this trench has been completed to
the required depth, the concrete is cast into the trench, where-
by during casting oftthe concrete, the bentonite slurry is forced
upwards and is continuously removed from the upper end of the
trench. During the castlng of the concrete, the earth forming
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.,
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075023
the slde walls of sald trench constltutes the parts of themolding box on the sldes of the trench, whlle on lts end, tem-
porary steel moldlng forms are lnserted to the full depth of the
trench to oreate therewlth smooth concrete surfaces agalnst which
the ad~iacent wall sectlon wlll be cast. The area of contact
between the two elements ln this manner obtalned, ls commonly
called "vertlcal ~olnt". The segment of dlaphragm wall so ob- - -
talned, ls commonly called "wall panel".
The maln functlons of the diaphragm wall structures are
as follows:
.
a) Retalnlng wall when from one slde of the wall the
earth ls removed.
Thls is for instance the case when diaphragm wall is
adopted for the construction of basement floors, underground
parkings~-or generally, underground constructions.
A diaphragm wall is installed all around the siee,
, thereafter the soil inside is removed to the designed depth, thus
`~ allowing the construction of the inside structure.
Another application is in the construction of tunnel
for subway or underpasses. Two diaphragm walls are installed at
the sides of the propo~ed tunnel and extend in longitudinal
direction of said tunnel, thereafter the roof slab of the tunnel
is cast and the soil thereunder is removed to form the tunnel.
b) Cutting off underground waters when a dlfference of
water level is orlglnated on the two sldes of the wall. The
.~
'~ 10750~3
ty~lcal case is in foundatlons Or dikes and dams to cut Orr water
seepa~e in pervlous strata Or soll.
c) Both retainlng wall and water cut off ln case Or
soll retainlng wall when the excavatlon ln one slde Or the wall
ls at a level lower than the water table level at the other slde
of the wall.
d) Foundation, when bullding or other structure are
founded on dlaphragm wall elements.
.
In order to accomplish with the ~unctions ~or whlch
the structure has been designed, particularly those Or earth
support and water interception, the vertical ~olnt between the
wall elements must f~lfll- the followlng requlrements:
..'~
1) to guarantee an effective key connexion capable of
withstanding the horiz~tal shear force which might be acting
on the ~oint as a consequence of dir~erent load conditions on
the two wall elements and
., :
2) to be watertight.
Accordingly, special attention must be given to the
moidlng forms for the concrete.
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10750Z3
DESCRIPTIO'~ OF TH~ PRIOR ART
A known molding form for formlng the vertlcal ~olnt be-
tween adJacent wall elements ls a clrcular, tubellke form called
"stop end pipe", having a dlameter eaual to the wldth of the
trench havlng been excavated. Such tubellke mold ls placed ver-
tically at the locatlon of the end Or the future wall eleme~t
prlor to castlng of the concrete. Once the castlng ls completed
and the concrete sufflciently hardened, the pipe is withdrawn,
leavlng a semlclrcular concave at the end surface of the concrete
wall. When constructlng the next ad~olnlng element, concrete
will be cast agalnst thls surface, thus reallzlng the ~oint.
At the orlgln of appllcatlon of dlaphragm walls, when
the wall thlckness was rather small, the clrcular plpe was
hltherto consldered the most approprlate mold form due to its
capablllty of wlthstandlng the pressure of the concrete, whlch
in the case of deep trenches is conslderably hlgh, whereby de-
flectlons of the p~pe form re~n wlthln acceptable values.
However wlth the dlffuslon of dlaphra~m walls and the
lncreaslng of wall thickness, such circular pipes in case of
thick walls give rlse to shortcom ngs.
A) The shear strength resistance of the Jolnt is
rather poortand relles more on the friction between the two
abutting surfaces rather than on an effective key. The concrete
at the extremities of the semlclrcular sectlon is generally
' 10750Z3
weakened, because due to the restrlcted space the concrete cast
under the bentonite slurry mlght be faulty or unsound, or hecause
that some areas of the concrete are often damaged by the chlsel-
ling action which is requlred to break and remove any excess
concrete which may have surrounded the plpe mold.
Therefore, the effectlve cr~ss-sectional area of the
~olnt ls reduced and moreover due to lts rather flat shape, the
shear reslstance of the ~olnt cannot be lncreased by appropriate
steel relnforcements. --
B) Such plpe molds comprise several plpe sections con-
nected to each other to obtaln a plpe of a length equal to the
depth of the slde Rall or dlaphragm, respectlvely. The coupllng
means between ad~acent plpe sectlons ls a compllcated matter be-
cause they have to wlth~tand the hlgh forces to whlch the plpe
ls sub~ect durlng lts pulllng out operatlon afterrthe concrete
has hardened and also because of the requlred hlgh accuracy re-
gardlng the allgnment of the plpe sections, such alignment belng
essentlal for the wor~.
C) The clrcular plpe necessltates the use of clamps
havlng a diameter equal to the dlameter o~ the plpe ltself, such
as to clamp lt durlng the pulllng-out operatlon. Thls follows ln
the requlrement of a masslve pulling out equipment which ls
expenslve regarding purchase cost and maintenance. - -
D) The adoption of a circular pipe of a diameter equal
` 1075023
to the width of the wall requires that the trench section
corresponding to one wall section must be excavated two pipe
diameters longer than the length of such wall section. This
leads to inconveniences and to a reduction of the progress rate
with consequent increase of the costs involved. It often also
leads to a limitation of a desired length and shape of a
diaphragm wall.
SUMMARY OF THE INVENTION
Hence, it is a general object of the present invention
to provide an improved construction of a metallic mold element
for concrete for the production of vertical joints in the con-
struction of diaphragm walls. Another object of this invention
is the provision of a metallic mold element for concrete
comprising a prism-shaped body including at least two oppositely
arranged parallel main side surfaces wherein a wedge-shaped
projection projects from one of said main side surfaces and
extends perpendicularly to the base surface of said prismatic
body.
Thus the present invention provides, in a metallic
mol~ element having a prism shaped body for use in the production
of vertical joints during in-situ construction of concrete
diaphragm walls by means of the slurry trench method of construc-
tion according to which the concrete walls to be constructed
are initially cast, wall section by wall section, into vertically
excavated soil trenches which are open at the ground surface
and extend in the longitudinal direction of the wall to be
constructed, the improvement wherein the surface of said prism
shaped body against which concrete is molded has a triangularly
shaped vertical projection means formed thereon and spaced from
the sides of the element to mold a vertical, trenching tool guide
in the end of the concrete wall section being cast, and the
~ ` .
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~075023
overall length of said metallic mold element extending in the
wall direction being less than its width and the width of the
diaphragm wall being constructed.
In another aspect the invention provides, in a metallic
mold element having a prism shaped body for use in the production
of vertical joints during in-situ construction of concrete
diaphragm walls by means of the slurry trench method of con-
struction according to which the concrete walls to be constructed . .
are initially cast, wall section by wall section, into soil
trenches which are open at the ground surface and extend in the
longitudinal direction of the wall to be constructed, the
improvement wherein said prism shaped body has an overall length
extending in the longitudinal direction of the wall to be
constructed which is less than its width and the width of the
diaphragm wall being constructed and has a concrete molding
surface comprising a pair of spaced co-planar surfaces which are
; transverse to the longitudinal axis for said wall and at least
a pair of intersecting, non co-planar surfaces forming a wedge
shaped projection means on said concrete molding surface.
In a further embodiment the present invention provides
a metallic mold element for use in the production of vertical
joints during in-situ construction of concrete diaphragm walls
by means of the slurry trench method of construction according
to which the concrete walls to be constructed are initially cast,
wall section by wall section, in soil trenches which are open
at the ground surface and whose walls extend in the longitudinal
direction of the wall to be constructed, comprising a prism
shaped body having parallel arranged side fàces extending
perpendicularly to the longitudinal direction of the trench and
- 30 spaced from each other; one of said side faces facing the
_ ~ - 8 -
`` ~0750Z3
portion of the trench to be filled with concrete and defining
with the walls of the trench a mold form for the concrete to
be poured to form a wall section; said one of said side faces
against which the concrete is molded having at least one
triangularly shaped vertical projection means formed thereon
to form a wedge shaped indentation on the concrete molded
surface; said side faces shaped and spaced from each other,
with one of said side faces having said vertical projection
means to mold a vertical trenching tool guide on the end of the
concrete wall section cast; the prism shaped body having an
overall dimension in the longitudinal direction of the trench
less than its width and the width of the diaphragm wall being
constructed. Preferably such a mold element is provided
wherein at least one plate projects from a top surface of said
prism-shaped body, said plate extending parallel to said
parallel arranged side surfaces, and wherein the slot is
provided at the base surface of said prism-shaped body, said
slot being intended for receival of the plate of a further mold
element. Further, preferably, such a mold element is provided
wherein said plate comprises a first through hole and said
prism shaped body comprises a second through hole, said second
through hole being located in the area of said slot, whereby
both said through holes extend parallel to secondary side
surfaces connecting said side faces and whereby in the case of
two mole elements placed upon each other the second through
hole of the upper element is in alignment with the first through
hole of the lower element, and wherein a pin is provided, said
pin adapted to extend through said first and said second through
holes connecting said two elements to each other.
In ,further aspects of the invention such mold elements
are provided wherein two parallel extending plates are provided
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`"` ~0750Z3
for connecting the mold element to another vertically arranged
mold element.
Also, such mold elements are provided wherein said
prism-shaped body is a hollow steel body.
~` BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and objects
other than those set forth above will become apparent when
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~0750Z3
consideratlon is glven to the following detalled descrl~tion
thereof. Such descrlption makes reference to the annexed drawlngs
whereln:
Flg~ 1 ls a section, ln longltudlnal dlrection of the
diaphragm wall through a trench provided with two pipelike molds
according to the prior a~t lnto which trench concrete is belng
cast,
Flgure 2 ls a sectlon along the llne II-II of Fig. 1,
Fig. 3 is a part of the sectlon of Fig. 2, shown in a
larger scale,
Flg~ 4, ~9~a sectl~on of a ~olnt between two diaphragm
wall elements cast accordlng to the prior art,
i
', Fig. 5 shows two sectlons~acco~dijng~to~e~e~t~no~f
~, Fig. 2, whereby one sectlon lllustrates a required length of
~, excavatlon according to the prior art and the other section the
required length of excavation when using the inventi w mold,
.'. - - .
, Flg, 6 ls a perspective view Or two mold elements,
`: :
Fig. 7 is a section in longitudlnal direction of the
diaphragm wall axls through a trench provlded wlth two m~ld
elements accordlng to the lnvention, into which trench concrete
is being cast.
~.
-- 10 --
: ' - . ' . ' . , ' -
`- ~075023
Flg ~ ls a sectlon along the llne VIII-VIII Or Flg. 1,
Flg. 9 ls a sectlon through a Jolnt between two dla-
phragm wall panels cast accordlng to the lnventlon,
' .
Fig 10 ls a sectlon slmllar to the section of Fig. 3
of an end portlon cast ln accordance wlth the invention,
Flg, 11 - Fig. 13 are sections of ~oints between side
walls obtainable by varlous embodiments of the inventive mold.
;~ Fig. 14(A) and 14(B~ are the same sections as shown in
Fig, 3 and 10, however, in case of abnormal quantity of concrete
surrounding the mold whlle casting the wall element 55,
,
- Flg, 15(A) ls a cross sectlon of the mold element,
typlcal for wall thlckness bigger than 1,00 m, and
! .
Fig. 15(B) shows the internai reinforcing plates of
~` the mold.
.. .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Describing now the drawings there is shown the prlor
art ln Fig. 1 and Fig. 2; a section of a trench 1 in longitu-
dinal direction of wall axis indicated by the arrow 2. The
ground level is indlcated by the -nU~r~a233 and the depth of the
trench by 4. Th~s trench 1 has been dug out in a known way by
-- 11 --
.
.
~` 10750Z3
means of a generally known trenchlng equlpment. In order to avold
a caving ln of the slde walls 5 of the trench thls trench ls
belng kept fllled wlth bentonlte slurry 6. At the two ends of the
trench there ls lnserted a plpellke mold 7, each havlng a clr-
cular cross-sectlon and oomprlsing several sectlons cQnnectedtbo
each other, not shown ln detall ln the drawlng. Thls plpellke
mold 7 constltutes the p~ior arb~ A dlp tube 8 ls lnserted lnto
the trench l and the bentonlte slurry 6. By means of thls dlp
tube 8 concrete 9 ls cast, whereby ~rlng the castlng the dlp
tube 8 ls contlnuously moved upwards. The concrete 9 fllllng con-
tlnuously the trench l urges the bentonlte slurry 6 upwards,
whlch slurry ls contlnuously removed ln a known way. The castlng
of the concrete 9 ls carrled out u~ll the requlred helght of
the lntended wall ls reached.
.
In Flg. 2 the cross-sectlon through the trench l ls
shown, whereby the wldth of the wall to be cast ls deslgnated -
wlth the numeral lO. Accordlngly, the two earth slde walls 5 of
the trench form two slde walls of the mold for the concrete 9,
whlch ls cast dlrectly agalnst these slde walls 5, whereby the
two end walls of the mold are formed by the outer surface areas ~--
faclng each other of the plpellke molds 7 whlch are constructed
ln accordance wlth the prlor art. :~
In Flg. 3 there ls shown an end area of the concrete ~
wall in the trench l in accordance wlth the prlor art, whereby ~ -
the concrete ls now hardened, thus formlng one completed wall
element. The mold 7, l~.e. the plpe has been pulled out by means
- 12 -
-~ 10750Z3
of a known pulllng out ma~hine. It ls now obvious that the plpe
mold 7, during castlng of the concrete 9 has been more or less
surrounded by excess concrete, leaving the circular concrete
residue lndlcated with the numeral 11.
The lntended effectlve ~oint contact area is shown by
12. The excess concrete 11 will be removed during excavation of
the ad~acent trench for the ad~acent wall element, lndlcated by
14. The areas 15 of the excess concrete 11 are weake~ed areas,
whlch wlll be removed untll the lines 13, which then deflne the
. contact area 12 of the ~oint. It is now obv ous that the exact
location of the lines due to mlssing edges is not defined, such
that~the~e,Xte~toof~the~contact,lsur~ace~`12,1s 7 also-not exaotly
, definable,
In Flg. 4 there are shown two completed ad~olning wall
sectlons, and speclflcally the ~oint therebetween. Lateral pres- '
sures actlng onbo the section 9 and the sectlon 14 are lndlcated
by arrows 16 and 17, respectlvely. If the pressure actlng on
sectlon 9 exceeds the pressure actlng on section 14, the ~olnt ls
sub~ected to a shearlng load and lt ls obvlous that such ~olnt is
rather not su~ to transmlt a large lateral load, in thls case
from the wall sectlon 14 to the wall sectlon 9.
,' Flg. 14 shows the end sectlon of the wall element 55
in the two,cases of vertlcal ~olnt formed according to the prlor
art (Flg, 14(A) and according to the lnvention (Fig. 14B), ln
case of abnormal quantity of concrete surroundlng the mola form
:
iO7S023
due to soll cavltatloniln the vlclnlty of the ~olnt.
In the case Or the prlor art (Flg. 14A) durlng excava-
tlon of the next element 56, the excess concrete wlll llkely
break along llnes 53 and 54, Thls wlll glve rise to a devlatlon
of the wall element 56 durlng lts excavatlon from the theoretical
axls 57 to the posltlon 58,
In case o~ the lnventlon tFlg~ 14B), durlng the excava-
tlon of the adJacent panel 56, the excess concrete wlll break of
course along llnes 51 or 52, ln both cases allowing the construc-
tion of the adJacent panel 56 ln lts exact positlon,
.
In Fig, 15A ls shown the cross-section Or the mold ~ -
element as per the lnventlon whlch is normally adopted in case of
wall thlckness exceedlng 1,00 m,
In this case two tr~angular proJections ar adopted,
In Flg, 15B is shown a detail of the lnternal rein-
~orclng plates t60) which provide the form wlth the rlgidity that
ls required to withstand the pressure of the concrete.
In Fig, 6 there ls now shown in detail a perspectlve
vlew of the lower part (19) and the upper part (18) of two
identical mold elements, manufactured in accordance with the in- -
ventlon, Each element 18, 19 ls a prism-shaped body havlng a
flat rear maln side surface 20, Furthermore said body comprlses
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,;" .
~0750Z3
a front maln side surrace 21, from whlch slde surrace 21 there
~ro~ects a wedge-llke ~ro~ectlon 23 conslstlng malnly of two
mating surfaces 24 and 25. Furthermore, the rear main side sur'
face 20 ls connected at one end by means of a perpendlcularly
extendlng secondary slde surface 26 wlth.~! one end of the front
main surface 21, and the opposlng ends of the main side surfaces
20, 21 are connected by means of a further secondary side surface
27 with one another, whereby the two secondary side surfaces 26,
27 extend parallel to each other. It ls to be noted that the
ridge 28 of the wedge 23 extends parallel to the slde sur~aces
20,21, 26~and 27.
-i5-
1075023
The body rurther has a to~ surface 29 extendln~ per-
pendicularly to e.~. the ridge 2~ and a bottom sur~ace 30 ex-
tending par~el to said top surface 29. From the top surface
29 there pro~ect ~wo platellke lugs 31, 32. At the bottom surface
two slits 33, 34 are provlded~ whereby sllt 34 is not shown. The
location and shape o~ the p~te 31 correspond to the locatlon and
shape of the sllt 33, and the location and shape of plate 32
correspond to the shape and locatlon o~ sllt 34. Accordlngly,
when two such elements 18,19 are placed upon each other (whereby
the actual number of elements placed upon each other is higher
and depends from the depth of the trench~ such as indlcated in
Flg. 6, which can be consldered an exploded vlew of a section of
the concrete mold, plate 31 ls inserted into the slot 33 and
plate 32 is inserted in slot 34.
Plate 3~ is provided with a through hole 35 and plate
32 is provided with a through hole 36, and, ~urthermore, the area
of the body 18 tand 19) is provided at the area of slot 33 with
a further through hole 37 and at the slot 34 with another through
hole 38,
~ he through holes 35, 37 and 36, 38 are located at
corresponding ~æ~t~o~ such that when the two elements 18, 19
are placed upon each other, a pin 39 can bè inserted through the
through holes 35, 37 being in register with each other thus
locking the two elements together. Obviously a further pin is
provided ~or p~ate 32 and slot 34, which however is not shown
in the drawing.
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10750Z3
Each element comprises further holes or openlngs 40
for recelpt of plns or hooks Or a pulllng out machlne~known as
such and thus not shown.
The bodles la, 19 are hollow steel bodles. They com-
prlse malnly two shaped thlck steel plates, whereby one ste~l
plate forms the rear maln slde surface 20 and half of each
the secondary side surfaces 26, 27 until the longltudinal line
41. The other steel plate forms the front surface 21 integrally
with ethe wedge 23 and the second half of the secondary side
surfaces 26,27. These two plates are welded together along the
line 41 which thus ls a welding seam 41. The body is thus com-
pleted by welding further flat steel plates to the first men-
tioned two steel plates, such th~t the top 29 and the bottom 30,
the pro~ecting plates 31,32 and also the slots 33,34 are ob-
tained.
The openlngs or through holes, respectively, are drilled
at a suitable step during manufacture of the plates or bodies,
respectiv~y.
In Fig. 7, which ls a sectlon similar to Fig. 1, there
is shown the casting of the concrete 9 lnto the trench 1 filled
with bentonite slurry 6, whereby the two steel molds 42 consist
now of a number of coupled mold elements shown in Fig. 6,
Referring now to Fig. 5, it has been mentioned earlier
that in order to construct the trench section 1 use is made of a
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~75GZ3
clamshell grab or other trenchlng equlpment, that the steel mold
gets placed and finally the concrete cast lnto the trench 1
pushlng the bentonlte slurry 6 upwards.
In order to obtain now one wall element 9 featurlng a
specific final length 43 it is obvious that a much longer length
44 of the trench must be excavated when uslng a clrcular steel
mold according to the prior art compared with the reduced length
45 of a trench which can be constructed by using the molds
according to the invention.
In Fig. 9, which is an enlarged end section of the
section of the wall shown in Fig. 8, whereby the ~oint between
two ad~acent cast wall sections is shown ln sectlon.
It is obvious, in comparison with the ~oint shown in
Fig. 4, an effective key eapable of transmitting large lateral
loads is obtained. Furthermore, the extent of the ~oint laterally
is almost two times the iength obtainable by means of the prior
art, such that an effectlve sealing off of ground water seepage
is obtained.
In Figl 10 there is shown the end section of a wall
element 9 after the steel mold has been retrleved and before the
excess concrete 46 has been removed. There exists here a sharply
defined line 47 unto which the excess concrete will be removed
thus leaving at every ~oint a well defined form of the face of
the wall segment 9.
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1075023
The trian~ular shape of the pro~ectlon 23 an~ there-
wlth obtalned ~oint as shown in Fig. 9 corresponds to the maxi-
mum~ shear resistance obtalnable, taking the quallty and the homo-
genelty of the concrete cast~under bentonlte slurry lnto consl-
deratlon,~ Furthermore, ln case of lateral forces of dlfferent
value acting on the ad~acent elements, the shear resistance can
be increased by means Or adequate steel reinforcements shown ln
Fig 13 lnstalled ln the wall elements, whereby the contour of
the ~olnt allows placing of the ste~l bars at the ~oint itself
~hereby such bars can overlap at the ~oints, relatlve to the
longltudlnal extenslon of the walls.
The thlckness of the inventlve mold ls very small ln
comparlson with the circular plpe. It nevertheless wlll, due to
its partlcular form, have a sufflclent rlgldlty such as to keep
the aeflection of the mold due to concrete pressures wlthln
acceptable llmlts. The rlgldlty of the form, due to said par-
tlcular shape, ls comparable wlth the rlgidity of the circular
plpe.
After pulllng out of the mold when one wall section is
sufflciently hard, tsee Fig, 10), there exists at the face of
the wall element 9 a void space 48 of such dimensions as to be
an efficient gulde for the clamshell grab durlng excavation of
the ad~acent wall element and to lmprove the progress of the
--19--
~075023
excavatlon. Moreover, due to the partlcular shape Or the race, an
e~flclent gulde ror the clamshell grab ls provlded.
,
Since many modlflcatlons, varlatlons and changes in
detall may be made to the descrlbed embodlments, it i~ lntended
that all matter contalned ln the~ or~g~ng~de~ ptiono~r~'sh-~n
ln~the accompanylng drawlngs be interpreted as lllustratlve and
7 not ln a llmltlng sense.
Accordingly, Fig. 11 shows a ~olnt when uslng mold
elements havlng a triangular wedgelike pro~ection about as shown
in Fig. 6, to be used when medium lateral rorces are expected. ~ -
.~ .
The basis 49 of the triangular pro~ection of an element
following ln a form o~ the ~olnt as shown ln F~g. 12, i's~shortér
than the one shown in Flg, 11, thus such ~oint is to be used
when comparatively smail lateral ~orces are expected.
The basis 49 according to Fig. 13 is needed ~or large ,
lateral forces, in which case steel rein~orcementssa~e~u~d~n
the wall segments and extending into the area of the ~oints.
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