Overhead MSS

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OVERHEAD SOLUTION

MOVABLE SCAFFOLDING SYSTEM

APRIL / 2014

Like the Underslung MSS, the Overhead MSS is a modern

equipment designed to allow cast in situ

equipment designed to allow cast in situ prestressed TT or

prestressed TT or

box

section full span concrete

section full span concrete decks

decks, in

, in bridges or viaducts.

bridges or viaducts.

The main diference

The main diference betwee

between the

n the two MSS underslung and

two MSS underslung and

ov

erhead

systems lies in the position of

the main structure in relation to the

concrete deck.

In the Overhead MSS the main str

ucture is placed above the

concrete deck and the formwork is suspended while at the

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Ma

in

co

m

on

en

ts

:

A- Main girder A- Main girder B- Noses B- Noses C- Rear support C- Rear support D- Transversal beams D- Transversal beams E- Main supports E- Main supports F- Launching wagons F- Launching wagons G- Main cylinders G- Main cylinders H- Work

H- Working platforms and ing platforms and laddersladders

I- External formwork I- External formwork J- Internal formwork J- Internal formwork K-Hangers K-Hangers L- Boxtom platform L- Boxtom platform

Suspended Formworks

The Overhead MSS is supported on top of

columns and the formwork

panels are suspended by threaded bars of

high strength.After

prestressing is installed the formwork panels are open using chain

hoists, winches or hydraulic cylinders, leaving the panels suspended

from the hangers.

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The special solutions

The Overhead can be designed to

special utilization where the columns

are too short, or where necessary to

ensure free heights as

ensure free heights as in railwaysin railways,,

roads or navigation channels

crossings.

In these cases the formwork can be

designed to open horizontally like in

a drawer rather than rotate arround

the hangers.

Boxh Underslung and Overhead

MSS solution can be made

symmetrical, meaning that they can

be used to cast the spans in boxh

directions without having to reverse

the MSS.

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Formw

Formwork ork openingopening

Overview of the Overhead MSS

Special front support using concrete

prefab legs.

Installing steel brackets at short columns

to support transverse steel beams

Formw

Formwork panels at open ork panels at open position duringposition during

lauching

Supports installed on top of transverse

steel beams anchored to the columns

V

Viieew w oof f tthhe e eexxtteerrnnaal l ffoorrmmwwoorrkk VViieew w oof tf thhe e iinntteerrnnaal l ffoorrmmwwoorrkk UUppppeer r ppaarrt t oof tf thhe e mmaaiin n ssuuppppoorrt t aanndd

lauching wagon used at lauching and side

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Rail and winch used to

Rail and winch used to open and closeopen and close

formwork panels

Main support and access ladder

Detail of the lauching cylinder

View in the lauching formwork direction

External formwork External formwork Internal formwork Internal formwork T Trraannssvveerrsse e bbeeaammss TTeemmppoorraarry y ssuuppppoorrt t bbeehhiinnd d tthhe e aabbuuttmmeenntt DDeettaaiil l oof tf thhe e wwiinncch h uusseed d tto o ooppeen n aanndd

close the formwork panels

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Pros and cons

In general terms we can

In general terms we can refer the followingrefer the following pros and cons of

pros and cons of the Overhead MSS whethe Overhead MSS whenn compared to the Underslung solutions; compared to the Underslung solutions;

Pros: Pros:

•

• Usually easier to assemble behindUsually easier to assemble behind

the abutment except in the cases the abutment except in the cases where the ground

where the ground elevatelevation behindion behind abutment allows the undrslung abutment allows the undrslung MSS to be

MSS to be assembled unrestricted.assembled unrestricted.

•

• Usually easier to move from oneUsually easier to move from one

deck to the paralel one, unless the deck to the paralel one, unless the ground elevation behind the ground elevation behind the abutment makes it possible to abutment makes it possible to lauchlauch the Underslung MSS till behind the the Underslung MSS till behind the abutment and then perform at this abutment and then perform at this working area the operation in working area the operation in question.

question.

Cons: Cons:

•

• Requires to leave more blockouts atRequires to leave more blockouts at

the concrete decks which are used the concrete decks which are used to suspend the formworks.

to suspend the formworks.

•

• The horizontal reaction forcesThe horizontal reaction forces

transmited to the columns are transmited to the columns are largerlarger than at the Underslung MSS since than at the Underslung MSS since this one is made by

this one is made by two halves andtwo halves and launching one half at a time launching one half at a time alternately transmits a smaller alternately transmits a smaller reaction force.

reaction force.

•

• In particular at the box sectionIn particular at the box section

decks the pre-assembled rebar decks the pre-assembled rebar cagecage is more dificult installed inside the is more dificult installed inside the external formwork than at the external formwork than at the underslung MSS.

underslung MSS.

•

• When there are two When there are two parallel decksparallel decks

and we are building at the second and we are building at the second one, it is not easy to take advantage one, it is not easy to take advantage of placing a mobile crane on the of placing a mobile crane on the first deck, because the overhead first deck, because the overhead main structure of the MSS hinders main structure of the MSS hinders or prevents placeme

or prevents placement of nt of the rebarthe rebar cages inside the formwork.

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Our services include:

-tender stage quotation preparation

-design, fabrication, deliv

-design, fabrication, delivery and

ery and technical assistance to the

technical assistance to the new equipment

new equipment

-rebuilt design regarding existing equipments deli

-rebuilt design regarding existing equipments delivered by us, for use in different conditions of

vered by us, for use in different conditions of the original

the original

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Mr. Aquilino Raimundo

Mr. Aquilino Raimundo Marketing and Sales Manager

Marketing and Sales Manager Strukturas as