Guide for bridge
constructions
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This guide shall be a help during the planning process in offer stage for bridge constructions
and can be used as a kind of checklist, too.
Additionally to this “Guide” all relevant User Information and technical newsletter has to be
considered.
Contents:
1.0 Questions which should be clarified additionally to the project sheet
1.1 Abutment
1.2 Pier
1.3 Superstructure
2.0 Abutment
2.1 Corner solutions
2.2 „Rucksack“ on the back of the Abutment-„Wall“ or Abutment-„wing“
2.3 Part of the Abutments – poured together with the superstructure
3.0 Pier
3.1 Combination Framax – Large area formwork Top 50
4.0 Superstructure
4.1 Staxo 100-scaffolding
4.2 Longitudinal beam Universal waling WS10
4.3 Cross beam H20
4.4 Side formwork for superstructure
4.5 Safety against horizontal load
4.6 Drive through opening
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1.0 Questions which should be clarified additionally to the project
sheet
1.1 Abutment
- Are there any horizontal construction joints which have to be considered?
- Are there any additional horizontal construction joints allowed?
- Are there any existing vertical construction joints? If yes, how does the reinforcement
looks like in these areas?
- How does the bottom side of the abutment- „wings“ look like?
- Is there a concrete wedge or is a bottom formwork necessary?
1.2 Pier
- Is it permitted to use tie-rods through the pier in longitudinal direction?
- Is it permitted to use/mix different formwork systems (e.g. for oval piers)?
1.3 Superstructure
- Where is the base/level for Staxo-scaffolding?
- How is the base? (transfer of loads to the base is to check by contractor)
- Do we have to integrate a camber of the superstructure to the scaffolding system?
- Is it permitted to do the bottom side of an arc superstructure polygonal?
- Is it permitted to use tie-rods through the superstructure?
- Do we have to integrate the formwork for the bridge edge beam to the side formwork?
- Is there any inclination in cross or longitudinal direction (when is not to see exactly on
building drawing)?
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2.0 Examples for execution of abutments
The shown description below is for explanation of some wording which you can find in this
chapter.
2.1 Corner solutions
From the geometrical point of view the abutment is like a thick wall.
In straight areas the formwork look like as for standard walls.
In corner areas you have to adapt the formwork solution to the large wall thickness.
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2.1.1 Tie rods
Especially the anchorage of the formwork has to be adapted. There are 2 possibilities to
adapt the anchorage, depending on the geometry.
- Right-angled corners, Tie-rods through the abutment-wall and abutment-wing
( wall thickness > 0,60m)
Execution with short tie-rod 15,0 , weldable coupler 15,0 and at least 2 rebars per
weldable coupler 15,0.
- Not rectangular corners, Tie-rods through the abutment wall or/and
abutment wing
Execution with short tie-rod 15,0 , weldable coupler 15,0, steel plate and at least 2
rebars per weldable coupler 15,0.
For above showed examples you have to take in consideration the Statical newsletter
No. 15 and 16 (ties across long distances)!
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2.1.2 Formwork height
There are always different pouring heights in the section point of abutment wall and
abutment wing.
Here it has to be considered that the formwork height for the whole corner area has to be the
same as for the wing (anchorage).
That causes often a quite big projection of the formwork.
2.1.3 Additional stiffening by panel struts
Due to stability reasons in corner areas (possible movements) there should be placed
additional panel struts.
The panel struts has to be fixed to the foundation with an express anchor or a proper dowel.
The formwork has to be fixed against lifting by the panel strut.
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2.2 „Rucksack“ on the back of the abutment-wall or abutment wing
There is often a Rucksack on the back of abutment wall or abutment wing
To reduce the amount of wooden parts to a minimum, which you need for form-adaption,
only the “stacked” formwork elements should be moved to the back of the “Rucksack”.
A bracket consisting of universal waling WS10, Corner connecting plate 90/50 and floor prop
will be used as working platform and also to transfer the vertical loads to the foundation.
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2.3 Part of the Abutment with Superstructure
According to requirements parts of abutment have to be poured together with the
superstructure.
In such cases it is much better to use supporting frames instead of tie-rods and rebars
across the total length of the superstructure.
If a customer wants to use tie-rods and rebars we have to inform that is nearly impossible to
pre-stress sufficient.
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3.0 Examples for execution of Piers
3.1 Combination framed formwork Framax Xlife with large area formwork Top 50
Bridge piers often have a circular or elliptical end. If there is no special demand to the
surface, you can use e.g. circular large area formwork Top50 for the end of pier and framed
formwork Framax Xlife for streight area.
In a rental market above mentioned formwork combination is normally cheaper as only Top
50, because the time period of a pier formwork on a simple bridge construction site is quite
short.
To have a proper possibility to connect Framax Xlife with Top 50 it is recommended to
assemble a Framax moulded timber on the Top 50 panel.
The moulded timber has to be fixed on the forming woods of the large area formwork Top 50
with nails or better screws. Now it is possible to connect both formwork systems together,
and the panel joint is not leaking anymore.
This connection normally is not able to transfer the concrete pressure out of stop end
formwork (circular Top 50).
Therefore the large area formwork has to be anchored additionally.
- Tie-rods through the pier are allowed (as in point 2.1.1 mentioned)
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- Tie-rods across the pier in longitudinal direction are not allowed
If the pier width is less than 1,20m the large area formwork Top 50 can be connected
together directly.
See example 1: e.g. three tie-rods will be combined in longitudinal direction with rod
connector 15,0. They are placed on back of framed formwork Framax Xlife. The
Universal waling 0,90 are used as bearings for tie-rods.
See example 2: On the back of framed formwork the Multi-purpose waling WS10 will
be fixed and connected together with plates. The Multi-purpose waling works as a
kind of tie-rod in longitudinal direction of the pier.
Example 1:
Example 2:
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4.0 Examples of execution of Superstructure
On all drawings has to be noted that the ground level has to be able to take all loads without
settlements (has to be checked by contractor).
All load bearing towers has to be build-in absolutely vertical.
4.1 Staxo 100
4.1.1 Direction of the Staxo 100 tower
It should be always tried that the bracing strut plane of the Staxo 100 tower is in longitudinal
direction of the bridge.
Advantages:
- „Strong“ side of the tower to the Wind direction => better load bearing capacity (see
user-information Staxo 100, frame plane and bracing strut plane)
- Smaller target for wind
- Easier adaptation to load situation at the cantilever eg. larger frame distance
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4.1.1 Multi layer towers
Multi layer towers offer a higher permissible load per leg.
Example from type test Staxo 100:
Supporting height max. 7,80m , working wind 0,2kN/m², horizontal load 1,0kN
4.1.2 Staxo 100 tower „held at top“ vs. „free standing“
Systems which are held at top offer a higher permissible load per leg (around 10 –
15%) then systems which are free standing. Out of that a lower quantity of material is
resulting and therefore also a lower price.
But if you consider also the material costs of the guying and labor costs which are
needed to assemble them, then very often the free standing systems are cheaper.
Example from type test Staxo 100:
Supporting height max. 7,80m, working wind + horizontal load 1,0kN at „free
standing“
„free standing“ „held at top“
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4.1.3 Towers with biggest frames 1,80m vs. biggest frames 1,20m
During concept work for a bridge also towers with the biggest frame of 1,20m should
be taken in consideration. Out of that a lower quantity of material is resulting because
of higher permissible loads per leg. If there is also is a lower price need to be checked
=> towers with only frames 1,20m and smaller are more expensive than towers with
frames 1,80m.
Additionally the situation on local stock yard needs to be checked.
Example from type test Staxo 100:
Supporting height max. 7,80m, working wind 0,2kN/m², horizontal load 1,0kN
Rahmen 1,80m Rahmen 1,20m
4.1.4 Working wind, storm wind
This topic is not included in that guide and is to handle according to the user
information “Doka load bearing tower Staxo 100” or the ”type test load bearing tower
Staxo 100”.
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4.2 Main beam Multi-purpose waling WS10
4.2.1 Statical layout
- Basic layout of the Multi-purpose waling WS10
For simple superstructures the below shown ratio of lenght should be considered:
Cantilever: Centre zone : Cantilever = 1 : 3 : 1
That offers a very good utilization of all components for following combinations
WS10 + Staxo 100, Itec + Staxo 40, 2xH20 + Staxo 40)
An exact calculation has to be done by Tipos
Example: ratio cantilever to center zone to cantilever, 1:3:1
- Main beam on two bearings
To have a better efficiency of the scaffolding system, it should be considered that the
walings are only supported by two bearings (no continuous span effect).
- Fixation of Multi-purpose waling WS10
To avoid tilting of main beams during the assemble process it is needed to fix the
walings to scaffolding system with locking rod 15,0, clamp plate and wing nut 15,0.
An advantage in addition is that it is possible to transport the top construction
together with the load bearing towers safely.
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4.2.2 Multi-purpose waling WS10 in longitudinal direction of the bridge
Advantage:
The Staxo 100 tower can be fixed easily against horizontal loads with standard parts to
abutment or piers.
Disadvantage:
The side formwork of the superstructures and to transfer the concrete pressure has to be
considered separately.
See 4.4.3.
4.2.3 Multi-purpose waling WS10 crosswise to the longitudinal direction of the bridge
Advantage:
Side formwork of the superstructure and also the transfer of concrete pressure can be
integrated easily to top construction.
Disadvantage at “held at top”:
The safety against horizontal loads (inclination, wind) has to be done in both directions of the
superstructure by additional measures (e.g. Panel strut).
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4.2 Cross beam H20
4.3.1 Cross beam on two bearings
To have a better efficiency of the scaffolding system, it should be considered that the beams
are only supported by two bearings (no continuous span effect).
4.3.2 Safety of the Cross beam
If there is an inclination of the bottom formwork the cross beams has to be fixed against
tilting.
That can be done with standard fastening parts of Large area formwork Top 50 (waling
clamp H20,…) or by contractor.
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4.4 Side formwork Superstructure
4.4.1 Assembling of Side formwork
To reduce the amount of forming woods and therefore also the costs, it is necessary to place
between plywood and forming wood a timber beam H20. For the statical calculation not the
“weak” plywood is the critical part anymore concerning distance of forming woods, it is now
the surface pressure between timber beam H20 and forming wood. With that execution the
amount of forming woods can be reduced about approx. 50 % and more.
Forming woods has to be connected to stabile unit.
4.4.2 Tying of side formwork
If tie-rods through the superstructure are allowed is this the cheapest solution regarding
material. The best is to place the tie-rods on the lowest third-point.
Based on the hydrostatic pressure the resultant of the concrete pressure is there and
therefore the best point for tie-rods.
There are maybe additional safety measures necessary against twisting, depending on the
geometry of the superstructures and the execution of the side formwork.
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4.4.3 Connection of the side formwork below the superstructure
If tie-rods through the superstructure are not allowed, there are below showed alternatives.
Example 1: main beam WS10 in longitudinal direction of the superstructure
The side formwork will be connected with parts from large area formwork Top 50. Therefore
Multi-purpose waling WS10, anchoring plate FF20 and tie-rod 15,0 will be put in additional
between the cross beams H20.
Example 2: Main beam WS10 cross the road
The side formwork will be connected directly with the main beam.
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4.5 Safety against horizontal loads
Additional to the horizontal loads by concrete pressure, also the horizontal loads, which
appear by inclination of the superstructure and wind, have to be considered.
4.5.1 Held on top in longitudinal direction of the bridge
A fixation (e.g. panel struts) in longitudinal direction of the bridge can be canceled if the top
construction is connected power griped with the abutment and the piers.
Power griped means e.g. Multi-purpose waling WS 10 across the whole superstructure
length with plates connected together and they are connected with tie-rods to the abutments
or piers.
(see 4.2.2 Universal waling WS10 in longitudinal direction of the bridge)
If the Multi-purpose walings WS10 are crosswise to the longitudinal direction of the bridge
the cross beams must be connected together. (e.g. with nailed wooden parts). The distance
of the nailed lines of cross beams should not be more than 1,50 m.
Generally the horizontal fixation should be as close as possible to the timber beam.
4.5.2 Fixation against horizontal loads
Look at statical newsletter 007.
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4.6 Drive through opening
Is an drive through opening necessary for traffic, there are 2 possibilities.
With load bearing tower Staxo 100 or heavy-duty supporting system SL-1
4.6.1 Drive through opening with load bearing tower Staxo 100
To transfer as much load as possible into the Staxo 100-scaffolding, following has to be
considered:
- All legs have to be loaded equally. (centric load transfer)
- No Continuous span effect (all beams supported by two bearings)
- The top construction shall pick up the horizontal loads
- The horizontal loads aren’t allowed to be transfered into the Staxo-scaffolding
- At the section points of the steel girders stiffening plates has to be welded to the steel
girders
4.6.2 Heavy-duty supporting system SL-1
This topic is not included in this “Guide”. In these cases we recommend to contact our
headquarter in Amstetten (Competence Center “Tunel”, Statical department).
