e-mosty December 2017 MSS and Formwork Travellers | Page 7

1. Movable formwork tables
Traditional formwork supported by shoring is made of
formwork blocks supported by beams placed over
propped shoring or beam shoring (Figure 2).
The fixed supporting structure can be made with
traditional shoring with multiple columns or by other
structures such as longitudinal beams or trusses
placed directly over their own foundations (on very
low bridges) or supported over columns directly
placed over the bridge piers foundations.
To use this system, it is recommended to have 2 sets
of supporting structures so that the following span
supporting structure can be installed while building
the previous deck.
Figure 2: Example of traditional propped shoring formwork
The movable formwork tables - Figure 3 - are normally
made of a steel structure which is stiff enough to hold
the form work panels that can be transported, lifted
and slipped laterally as well as longitudinally, over a
fixed supporting structure, making a modular block
that normally is called movable formwork table.
When the movable tables are released from the
concrete they are longitudinally moved over the
waiting supporting structure to prepare next span
casting.
This system also requires the preparation of the
ground: for multi shoring; accesses of trucks and
cranes to erect and dismantle n times the supporting
structures; and initial assembly and final disassembly
of the movable tables.
This system obviously requires lots of man power and
auxiliary machinery such as cranes and trucks for the
repetitive operations of assembly, disassembly and
movement of supporting structures and tables.
The movable formwork tables are an easy
construction system for low decks with a short
number of spans, when a more sophisticated method
is not necessary.
The cost of using this method is similar to the cost of
traditional propped shoring systems, but with better
efficiency achieving cycles of one span every two
weeks, for spans between 25 m and 36 m.
Figure 3: Example of movable formwork tables –
casting position (above) moving (below)
The formwork tables can normally be moved in the
three directions of space:
 Vertically – allowing moulding and demoulding of the
deck
 Laterally – allowing the table to pass the pier of the
current span
 Longitudinally – allowing the table to move to the
following span.
4/2017
2. Movable Scaffolding Systems – MSS
2.1 Underslung
The system of movable formwork tables was the
origin of underslung Movable Scaffolding Systems,
where it is the supporting structure that can move
itself in the 3 main directions, carrying the outer form
to the following span.
The primitive underslung MSS were made of
independent structures placed under the level of the
deck, with some parts being dismantled and replaced
on the next span by auxiliary machinery such as trucks
and cranes, as shown in Figure 4.