Staxo

Staxo04/99 Calculation Guide

© by Doka Industrie GmbHA-3300 Amstetten

Important notice:

Always observe all relevant safety regulations applying to the use of our products inthe country in which you are operating.

Many of the illustrations in this brochure show the situation during formwork assemblyand so may not always be complete from the safety point of view.

The functional/technical instructions given in this brochure must be adhered to exactly.If any deviations from these are contemplated, confirmatory statical calculations mustbe performed first.

We offer special training seminars to users of Doka formwork products. These giveparticipants a great deal of useful information on how to make the best possible useof the products, both from the technical and the commercial point of view. If needed,we can provide trained supervising foremen to give on-site formwork instruction.

It would be dangerous to combine our formwork systems with those of othermanufacturers. This point should be checked very carefully first.

We reserve the right to makealterations in the interests oftechnical progress.

3

Contents 3

Description 4-7

Tower set-up 8

ComponentsBasic frames Staxo 9Diagonal crosses 10Screw-jack heads and feet 11

Bearing capacity diagramsSupporting scaffold held at top 12Free-standing supporting scaffold 13-15

Sample calculation 16-17

Notes 18-19

Doka addresses 20

Contents Page

4

Description1. AREA OF UTILISATION

The supporting scaffold STAXO consists of Staxo frames ("basic frames Staxo"), d2 screw-jackheads and feet, and diagonal crosses. It is used for transferring vertical and horizontal loads inplanned perpendicular positions.

The Staxo supporting scaffold shown in the overview drawing on p. 8 is made up of Staxoframes that are braced - orthogonally to their plane - with diagonal crosses. Screw-jack headsand feet are used for adjusting the height.

All load-bearing parts are made of steel, while the connecting sleeves of the Staxo frames aremade of aluminium.

Bearing capacity diagrams are given for:- top-held supporting scaffolds- free-standing supporting scaffolds

When supporting scaffolds are used, the national or - where available - European standardsgoverning their use must be observed.

2. DESIGN DESCRIPTION

2.1 Individual components

The supporting scaffold STAXO is put together from the following components - see pages 8to 11:- Basic frames Staxo 1.80 m, basic frames Staxo 1.20 m and

- Basic frames 0.90 m for adjusting the height

- Diagonal crosses *)

- Heavy-duty screw jack 70 with split-nut or screw-jack foot

- Screw-jack U-head or U-head

The different heights of the Staxo frames and the available spindle travel mean that continuousheight adjustment is possible.Various different diagonal crosses are available for coupling the frames, enabling frame spacingsfrom 1.0 m to 2.5 m, with Db = 0.5 m.

Transverse bulkheads in the form of horizontal diagonal crosses must be fitted to the bottomframe, and then to every 2nd frame.

*) The diagonal crosses can be replaced by horizontal and diagonal braces. For set-up details,see the d2 brochures and the User Information booklets.

2.2 Materials, corrosion protection

The vertical profiles are made of StE 355. For the other parts of the Staxo frames and for thediagonal crosses, St 37-2 is used. The screw-jack heads and feet are made of St 52-3 and havea coiled trapezoidal thread. The nuts are made of Ck 45, and the split nuts of GTS 45.

All components are hot-dip galvanised.

5

3. STATICAL VERIFICATION

3.1 Assumed loads

The loading assumptions must be made in accordance with the valid Eurocodes and/or natio-nal Standards.

Live loads

The effective resistance (allowable perpendicular leg loads) can be determined from the bearingcapacity diagrams. Compared to the live loads, the dead weight of the supporting scaffold isinsignificant and can be ignored.

Horizontal loads

With free-standing supporting scaffolds, allowance must be made for the horizontal loads actingon the head.

Wind loads on the supporting scaffold

The computed wind loads allowed for in the diagrams were determined as follows:

- Wind load area:Wind acting on the frame plane: AW = 0.40 / 0.38 m² per rising mWind acting on the bracing-strut plane: AW = 0.27 / 0.23 m² per rising mfor basic frames Staxo 1.20 m / 1.80 m

- The aerodynamic force coefficient is cf = 1.85. The stagnation pressure is Qw = 0.50 kN/m² forH < 8.0 m, or 0.80 kN/m² for H > 8.0 m.

Extra horizontal loads

An equivalent load of 1/100 V must be assumed for the extra horizontal loads, in accordancewith DIN 4421, Section 6.3.1.4.

Constrained loading cases

Constrained loading cases, such as e.g. varying settlement and movements of the superstructurecaused by temperature changes, must be examined separately where required.

3.2 Verification procedure

The effective resistance (allowable leg loads) was determined by testing.

6

Description4. Basic points for planning and erection:

4.1 Footings

The screw-jack feet must be placed on flat, unyielding, surfaces.

The assumed horizontal fixture at the head of the supporting scaffold must be realised byappropriate measures:The superstructure (formwork) must be immovably fixed to existing walls or columns, and/orto other firm structural components. The bearing reactions can be determined from the sum ofall horizontal loads.

The Staxo towers must be erected in the vertical. The maximum permitted inaccuracy of erection(deviation from the perpendicular) is:1 % of the height of the tower, but no more than 30 mm

4.2 Safety against slippage and toppling

Measures to ensure that there is no risk of the supporting scaffold slipping or toppling must bespecified in individual cases, and verified. Normally, slippage of each individual leg will be thedeciding factor here (see bearing capacity diagrams).

4.3 Lifting by crane

The following points must be observed when lifting the towers by crane:- maximum height of Staxo towers to be lifted by crane: 10 m.

This applies both to the hoisting of towers that have been assembled on their sides and tothat of upright towers

- all the locking springs at the frame joins must be shut.

7

5. USING THE BEARING CAPACITY DIAGRAMS

5.1 General remarks

The loads acting upon the screw-jack heads which have been calculated for the application inquestion must be compared with the effective resistances (allowable leg loads) given in thebearing capacity diagrams.

In the event of unequal leg loads (max FV/min Fy < 2) or unequal screw-jack lengths on theheads (supporting scaffold for supporting inclined longitudinal beams), the maximum leg loadmust be compared with the allowable leg load for the maximum screw-jack length.

The bearing-capacity data do not apply to supporting scaffolds with only one "basic frameStaxo 1.80 m".

5.2 Free-standing supporting scaffold

The effective resistance (the allowable vertical leg loads), as a function of the simultaneouslyacting horizontal loads, is given for the various heights in the bearing capacity diagrams. Infor-mation is given separately for the frame plane and the bracing-strut plane, frame spacings of1.5 m to 2.5 m being permissible here. For frame spacings of 1.0 m, the diagram contains anextra line for heights of up to 6 m. The maximum screw-jack extension lengths are all shown inthe diagram.

There are no limitations regarding the arrangement of "basic frames Staxo 0.90 m, 1.20 m or1.80 m".

The minimum applied loads needed to ensure that the less heavily loaded screw-jack-feet aresafe from slipping are given in the bearing capacity diagrams for a frictional value of m = 0.3(steel on concrete).

5.3 Supporting scaffold held at top

The effective resistance (the allowable vertical leg loads) is given in the bearing capacity dia-gram as a function of the height, and of the lengths of the screw-jacks.

The information given applies to frame spacings of 1.0 m to 2.5 m.

The "basic frames Staxo 1.80 m, 1.20 m and 0.90 m" can be combined in any way desired.

8

Screw jack U-head

or U-head

Top storey

Middle storey

Bottom storey

Screw jack foot

or heavy-duty screw jack 70

Tower set-up

9

A

B

A

A

B

B

Cross section ofvertical profile

Cross section ofvertical profile

Detail A

Detail B

Basic frame Staxo 0.90 m Basic frame Staxo 1.20 m

Basic frame Staxo 1.80 m

Components

Basic frames Staxo

10

Frame spacing 200 cm

Basic frame Staxo 1.80 m

Designation of diagonal crosses

e.g. 18.200

Designation Frame spacing Hole spacing Peg spacing

A B C

Diagonal cross 18.100 1000 1993 1724

Diagonal cross 18.150 1500 2285 1724

Diagonal cross 18.200 2000 2641 1724

Diagonal cross 18.250 2500 3037 1724

When used on "basic frames Staxo 1.80 m"

Components

Diagonal crosses


A B C

Diagonal cross 9.100 1000 1282 802

Diagonal cross 9.150 1500 1701 802

Diagonal cross 9.200 2000 2155 802

Diagonal cross 9.250 2500 2626 802

When used on "basic frames Staxo 0.90 m"


A B C

Diagonal cross 12.100 1000 1488 1102

Diagonal cross 12.150 1500 1861 1102

Diagonal cross 12.200 2000 2284 1102

Diagonal cross 12.250 2500 2732 1102

When used on "basic frames Staxo 1.20 m" and as horizontal diagonal crosses

11

Screw jack foot

Heavy duty screw jack 70

U-head

Split nut

Screw jack U-head

Screw jacks

Mat: Ck45

Mat: Ck45

Mat: GTS45

Mat: St37-2

Bottom edgeof beam

Sp

ind

le e

xten

sio

n

len

gth

LK

Sp

ind

le e

xten

sio

n l

eng

th L

F

Sp

ind

le e

xten

sio

n l

eng

th L

F

Bearing surface Bearing surface

12

0 5 10 15

À

Ä*)

Â

Ã

Á

À

Á

Â

Ã

Ä

Ä*)

0 5 10 15

Ä

FV FV FVFV

H

L KL F

À 20 cm 20 cm 20 cmÁ 25 cm 30 cmÂ 30 cm 30 cm 30 cmÃ 35 cm 45 cmÄ 35 cm 70 cm


Bearing capacity diagramsupporting scaffold held at top

Height H of supporting scaffold [m]

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

without wind

with wind

*) Space between sections >1.5 m

Basic framesStaxo 1.80 m,1.20 m or 0.90 m

Screw jack footor heavy dutyscrew jack 70

Screw jack U-head or 4-wayscrew-jack head

Bracing-strut or frame plane

1.0 - 2.5 m

(1.5)*)

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0


Screw jack Screw jack Heavy dutyU-head foot screw jack 70


13

FVFV FVFV

FH FHFH FH

L KL F

Bearing capacity diagramfree standing supporting scaffold

LF max. 20 cmLK max. 20 cm

LF max. 30 cmLK max. 30 cm

Permitted horizontal load FH per leg [kN]

Height up to 8.0 m

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

bracing-strut plane

frame plane

bracing-strut plane

frame plane

frame plane

frame plane

bracing-strut plane

bracing-strut plane





Calculation also allowsfor wind acting on thesupporting scaffold, andfor accuracy of erection

1.5 - 2.5 m

max

.8.0

m


10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

0 0.5 1.0 1.5

0 0.5 1.0 1.5

14

FVFV FVFV

FH FHFH FH

L KL F

10.0

20.0

30.0

40.0

50.0

60.0

70.0


Height up to 6.0 m

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

bracing-strut plane

frame plane

frame plane

bracing-strut plane


1.5 - 2.5 m

max

.6.0

m





0 0.5 1.0 1.5

LF max. 40 cm with h.-d. screw jackor max. 30 cm with screw jack footLK max. 40 cm w. screw jack U-head


15

FVFV FVFV

FH FHFH FH

L KL F

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0LF max. 30 cmLK max. 30 cm

1.5 - 2.5 m

max

.6.0

m

0 0.5 1.0 1.5

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

Height up to 6.0 m


frame planebracing-strut plane

10.0

30.0

50.0

80.0LF max. 20 cmLK max. 20 cm


frame plane






bracing-strut plane



0 0.5 1.0 1.5


bracing-strut plane 1.0 m

bracing-strut plane 1.0 m

20.0

40.0

60.0

70.0

(1.0)

16

40 kN

60 kN

ÔÔÔÔ

40 kN 60 kN

FHFHFHFH

FV FVFVFV

L KL F

0 0.5 1.0 1.5Permitted horizontal load FH per leg [kN]

Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

Height of supp.scaffold <6.0 mScrew-jack extension <30 cm

Horizontal load

Wind load: W = 1.0 kN per row of legs2 adjacent towers

W/number of legs= 1.0 = 0.25 kN per leg 4

H1 = 60 + 0.25 = 0.85 kN H2 = 40 + 0.25 = 0.65 kN100 100

Slab bridge

Frames placed at right-angles to the bridge superstructure (free-standing in the frame plane).

A) Check (verification) with reference to the "free-standing supporting scaffold" bearing-capacity diagram

for the transverse bridge direction:

max. V = 60 kN H = 0.85 kNmin. V = 40 kN H = 0.65 kN

The point at which max. V and H intersect must be below the allowable structural-design (calculation) line forthe frame plane.The point at which min. V and H intersect must be above the line for slippage.If this intersection point lies below this line, then the screw-jack feet must be fixed to the surface on whichthey are standing (bolted onto floor/ground), or linked together with scaffolding tubes.

Height up to 6.0 m

Transverse beamsfishplate-bolted(no horizontal forces,owing to pressure ofstop-end formwork)

Sample calculation

In the longitudinal bridge direction, the formwork is held by the bridge-superstructure supports or piers. Inthis direction, therefore, no horizontal forces occur (held by the head in the bracing-strut plane).

0.85 kN0.65 kN

80.0

70.0

60.0

50.0

40.0

30.0

20.0

10.0

bracing-strut plane

frame plane

0.85

kN

bracing-strut plane

frame plane

LF max. 30 cm

LK max. 30 cm

0.65

kN

Basic frames

Staxo 1.80 m,

1.20 m or 0.90 m

1.5 - 2.5 m

max

.6.0

m


Screw jack foot

or heavy duty

screw jack 70

Screw jack U-

head or 4-way

screw-jack head

17

À

ÁÂ

Ã

Ä

60 kN£ 6

m

0 5 10 15

Ä


B) Check (verification) with reference to the "supporting scaffold held at top" bearing-capacity diagram

for the longitudinal bridge direction:

max. V = 60 kN (without horizontal load)

The point at which max. V and the tower-height intersect must be below the structural-design (calculation)line for a 30 cm screw-jack extension for the allowable load.

with wind


Per

mit

ted

ver

tica

l lo

ad F

Vp

erle

g [

kN]

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0


18

Notes:

19

Correct formwork designsaves materials and time

In all formwork tasks, it is exceedingly importantto ensure that the formwork is correctly designed.

The Doka branch nearest you will be pleased to give youinformation and literature on Doka's formwork systems.

A telephone call is all it takes!

AI 38

The Doka Group's central plant at Amstetten, Austria

GB

Doka internationalDeutsche Doka

Schalungstechnik GmbH

Frauenstrasse 35, D-82216 Maisach, GermanyTelephone: (0 81 41) 394-0, Fax: (0 81 41) 394 405

E-Mail: [email protected]

Österreichische DokaSchalungstechnik GmbH

Reichsstrasse 23, A-3300 Amstetten, AustriaTelephone: (0 74 72) 605-0, Fax: (0 74 72) 6 44 30E-Mail: [email protected]

Internet: http: // www.doka.com

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Schalungstechnik GmbHDoka Branch Lebanon

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Documents

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