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ADVANCED FLOORING FORM WORK SYSTEM FOR REINFORCED MASONRY

by

Shigeru Nisugi

New Business Center. Sumitomo Heavy 1-21. Kandanishiki-chou. Chiyoda-ku.

Takayuki Fukushima

Industries. Ltd .• Tokyo. 101. Japan

Technical 2-32-1.

Research Inslilule. Haseko Corporalion. Sh i ba. M i na lo-ku. Tokyo. 105. Japan

ANO

Yuusaku Seki

Seki Building Malerial Inslitule. ·3-14-6-401. Harumi-dai. Sakai. Osaka. 590-01. Japan

ABSTIlACT

Re i nforced Masonry (IlM). deve I oped by U. S. -Japan Coord i­naled Earthquake Research Program on Masonry Buildings since 1984. is almost compleled as lo slruclural aspect, and only the decision expected.

However. lhe research and development as to building aspect is I ively being carried out al presenl. Development of wooden flooring form work syslem of self-slanding type (VS Formwork Method).which has more flexibililY lhan Half PC flooring system. is one of them.

In this paper. we would I ike to inlroduce Japanese VS Formwork system. melaI filling for fixing. actual building re­cord. and a performance lesl of cross section.

Precast concrete (PC) floor slabs or semi-PC slabs which are used in the conventional industrialized building construc­tion are in essence factory-made products manufactured through labor-intensive processes in factories. As such. their qualities and precision have been.not to a small extent. maintained by the specific experience and perception of skilled trade workers. In a prospective view of a newly emerging industrialized building production system which is to be used in the next 21st century as well. a new type of manufacturing processes needs to be established in which the product qualities and precision should be controlled by industrialized techniques rather than by the experience and perception of skilled workers.

new In such a new industrialized building production system a type of floor/beam formwork con~truction method which is suitable for reinforced concrete structural construction prefabricated formworks was provided and named "Verbund

most using

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Scharnngs Floor System(VS Formwork Method)". Table I indicates a variety of floor slab construction systems which are available at present. In the pasto numerous industrialized production methods for concrete floor slabs were developed: however. it should be noted that almost ali products manufactured by such methods were those which were to be produced through labor­intensive processes at factories. Since such processes were essentially oriented to mass production of a limited variety of products. they could not be expected to provide a rich variety of product sizes. Only steel floor decks allowed some freedom of dimensional choice. (See Photo 1 RMSS Construction Method.)

Through comparative studies of various formwork methods now available. various aspects of the industrialized floor slab construction method will be viewed from multiple angles.

LIGHTWEIGHT FORMS EASY TO TRANSPORT

VS Formwork Method. which we intend to introduce to you as concrete floor forms which are featured by good workability are wood-based form panels provided with Kaiser bars and Omnia bars which are self-stabilizing. These forms are to remain in place to be integrated with concrete forming permanent structural elements. AlI temporary materiaIs reQuired for this formwork are lightweight and can be easily transported.

NO RESIDUAL MATERIALS TO BE REMOVE0

Besides reQuiring skill of carpenters for their fabrication. conventional wood formwork always makes it necessary to dis­mantle forms and remove them from the construction site after concrete has been placed and let to set. Reinforced concrete construction using a formwork with masonry precast units. ensures a high degree of precision through construction. which fully warrants accuracy of dimensions as well as stability of Quality. A similar statement applies also to the floor construction method using VS Formwork Method. In this particular type of forms. bars forming highly self-stabilizing space forms serve as supporting bars and concurrently as main structural bars. When concrete is deposited against these VS Formwork. high precision. high Quality reinforced concrete floor slabs fully integrated with permanent form panels can be obtained.

SYSTEM COMPOSED OF OPEN TYPE PARTS

Since the formwork with masonry precast concrete units is composed of open type parts which are widely disseminated in the construction market. the floor concrete system should preferably be composed of open type parts as well. In VS Formwork Method. parts used are of an open lype which can be fabricated freely based on the modular protocols. Further. reinforcings bars fabri­cated to form self-stabilizing space frames. which support panels. are also of an open type that can be set to the optional lengths for embedment in concrete. (See Fig. 1). Thus. most desirable conditions are combined in this system.

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FREE EXPANSE OF SPACE MUST BE ENSURED

As long as parts used to form the floor concrete formwork are industrial products. factory-manufactured building elements are inevitably unified to certain standard sizes . Basic elements of formwork with masonry precast concrete units are based on modular dimensions both in the X-direction and in the Y-direc ­tion. (See Fig.2). Since modules are minimum units for dimen­sional coordination. the formwork based on modules is flexible in conforming to any desired space composition. At the some time. the floor formwork should be composed of as large unit panels as possible to readily the need for planar expansion . Wood-based panels which are light in weight and can be easily cut to desired sizes and shapes are highly favorable in this respect .

SAVING LABOR FOR TEMPORARY INSTALLATION

Where PC elements ar e used for such structural members as columns. wall and beams. temporary concrete forms for floor slabs need their own ' temporary supports to ensure their lateral rigidity.

VS Formwork Method mentioned above is intended to minimize labor required for such temporary work and to maintain lateral rigidity of the temporary floor forms (See Fig.3). In their typical application. VS floor formworks are placed on the top of reinforced concrete walls constructed by using formwork with masonry precast concrete units . The self-stabilizing trussed reinforcement of the VS floor formworks is fixed to the walls at the both ends. The horizontal members consisting of trussed reinforcing bars give laleral rigidity to the floor forms. The wood decks of the forms are faslened lo the trussed steel bars and when concrete is poured againsl the forms. they are integrated with concrele (See Fig.4). Since lhese forms are brought into contacl with lhe precast concrete wall surfaces. it is desirable that rubber packings or lhe like be inserted into the joints between the floor forms and lhe walls to preclude concrete leakage through such joints.

STUDIES OF LOADING TESTS USING VS FORMWORK METHOD

1) PURPOSE The studies at this presenl phase are primarily intended to

verify the sectional properties as obtained by the VS Formwork Method.

2) TEST SPEC I MENS Fig.5 shows the shape of Kaiser bars as fabricated. Fig.6

and Photo 2 show Type A Specimen. In Type A Specimens . the melalware was spaced out 200mm and

300mm at the end portions and lhe intermediate portions respectively. Also. metalware was placed close to the points of support at the end portions . No changes were made in respect of the shapes of Kaiser bars and lhe metalware .

Particle boards. cemented woodwool boards and composition panels were used as wood-based formwork materiaIs.

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3) LOAOING ANO MEASUREMENT METHOOS a) ESTABLISHMENT OF LOAOING

It was assumed that the formwork for the floor was subject to a combined Ioad of 700Kg/m2 . This comprised the deadweight of concrete (460Kg/m 2 ), Lhe temporary construcLional load (150Kg/m2 )

and the impact load (taken as 20% of the concrete deadweight). The formwork was supporLed at a span of 1. 7m.

b) LOAOING METHOO As an alternative for actual concrete placement, a number

of sand bags (30Kg each) were placed in the form of a uniformly distributed load applied in one direcLion.

c ) MEASUREMENT METHOO Fig.7 shows the measurement method used. In order to

ascertain the deflection of the formwork, the vertical deflec­tions of the formwork at the points where metal fittings are located were measured .

4) TEST RESULTS ANO CONSIOERATION The test results are a's shown in Fig . 8. A series of charts

in Fig . 8 indicate the verlical deflection of respective form­works at the respective points of measurement under each loading increment only. A load of 1020Kg corresponded to a unit load of 670Kg/m2 • The maximum deflection near the midspans are indicated in Table 2 for different types of formworks.

If the leveI accuracy of the floor is assumed to be 1/300 and the allowable deformalion of lhe floor formwork alone is taken as 1/4 of the overall deformation. the allowable deforma­tion of the floor formwork is 1. 42mm for a span of 1700mm.

The particleboard forms showed the deflection of 2.35mm under the test load. which indicates that this type of forms is insufficient in rigidity . Since use of more metal fittings is considered impracticable. lhe solution should preferably be sought by increasing the rigidity of kaiser bars and/or by reducing the form spans.

The allowable span which can limit the deflection to within 1/1200 of the span may be obtained by the following formula .

L '= 3 Ja X ~ . X L

where. L': Allowable span L Span (1700mm as established for the experiment) õ Maximum defIeclion (lhe value as established for

the experiment) a : Allowable levelness deviation (1/1200)

Table indicates the computed values. In the case of the particleboard forms. it is known by making reverse computations from the experimental values that the deformation of this type of forms can be restricted lo within the allowable limitation if their spans are reduced to 1400mm.

As for the supporL spans, form panels each having a length of 1800mm must be supported at 900mm intervals or a series of panels must be supported conlinuously.

5) CONCLUSIONS The test results described above indicate that the proper

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design of Kaiser bars and/or proper establishment of support spacings are lhe faclors of prime imporlance. If such design and eslablishmenl are adequate. VS floor ~ormworks may reasonably be expected lo serve the inlended services satisfaclorily.

In case of conventional floor formworks. forms are propped by a number of support members narrowly spaced therefore. the difference in lhe degree of deformalion belween any form and lhe adjoining form does nol need lo be sludied: however. in lhis particular type of formwork. the difference in deflection re­sulting from one form being loaded and the adjoining form not

being loaded musl be considered.

lable 1 Former FloPf lndustrialization Hethods

""'1 tl"O .. ,

-7- .

~L . , . ". :;~:~ : • • .'.... ... . .. '-.:..!....-

.... 1'7'"

1 • •

!I!;J'-II ~ .. , P"

l~rW~ - ~ ---,. .. .-

m2~~iaspSPwJ

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Photo ,I RMSS Construction Hethod

Fig 1 Adaptabi I i ty of Optional Standard Sizes.

fig 3 Arrangement of wall-to­floor junction in VS formwork Method

Fig 2 Module Formation

Fig 4 Typical Fastenings used for floor forms by VS Formwork Method.

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Fig 5 View af Kaiser Bars Phata 2

300 ,I, 300 .I. 300! !OO ,I, !OO .1 ,)so

I !50 ,I, 300 300 ,I ISO .1

Fig 6 Type A Specimen

\\ ••• · 610 kll c. ' @!!!!'kf«i!l~ 1J+;'i(,jií ~'o:HlJíij .... J4i<,íW,p ''I! ~,'·AAiI ,J,ijilíllllíh Qijij;iIíWii' ! .. ..

~"'1"1-217k' •• _________

.. ~ I o ti

.. O O O O Ô O

..

~J: 100 ,I, !OO I 300 .I 300 300 ,I 100 ,I~ !OO

:~~I 'i

1, 100

Fig 7 Hethad of Loading and Heasurement

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VS Floor Formwork Method Load -Deflection Relationsh i ps. Form Material:Composition Panel 12mm ~-rr~~----~~------------------~

6. 4 e . 8 1.2 1.6

unit(m) Distance from Support(m) .

9 9. 4 0 . 8 1.2: 1, 6

Distance from Support(m) uni t(m)

VS Floor Formwork Method Load -Deflection Relationships. Form Material:Particle Board 25mm

1-

... •. 8 L2 1.'

un i t (m) Distance from Support(m)

VS Floor Formwork Method Load -Deflection Relationships. Form Material:Woodwool Board 25mm

:; :IL~" __ D---------e468 ;: ';~~;:;~;:;;;:~;~~~t ~ -3 -2.812 -2.91"

Q) '

.Q ~~--~---r---r--.---.---r-~r--.--~ o QUI 0.9 1.2 1.6

Distance from Support(m) uni t(m)

Fig 8 Deflections under Various Loading lncrements

Table 2 Maximum Defl ections and Allowabl e Spans (mm)

TcsL Spp.cimc fls

Composition Panels

Particle Boards

Tili ckflc s s Maximllln Dcfl ccliofls

Allowabl\~ Spans

1,26tJ

------- ------.-- ._-- --- -

25 2.35 1,436

-------- 1------------ --- - ---- ---------- ------ ----.-

Woodwool Boards 20 2.73 1, :l66

LS L.DI