Thanh Tri Bridge

MSS Moving Scaffolding System

INTRODUCTIONMain Products Applications Step by step erection Preparation for concrete Pouring concrete Launching

Main Products Applications

MSS - Moving Scaffolding SystemSpan length 15 - 80 m Usual Total Length 500m several kms

Underslung MSS Components.. .. ..

SUPPORTING BRACKETS LAUNCHING WAGON MAIN GIRDER TRANSVERSE BEAM EXTERNAL FORMWORK INTERNAL FORMWORK

A typical construction cycle with the underslung MSS.. .. ..

After concreting, curing and tensioning of cables, the Main Girders are lowered by the main jacks at the rear and front Pier Brackets.

A typical construction cycle with the underslung MSS.. .. .. .. ..

The joints in the middle of the Transverse Beam system are released and the Main Girders are moved transversely into a position where the Transverse Beams can pass the piers.

A typical construction cycle with the underslung MSS.. .. .. .. ..

The MSS is ready for launching. The launching operation to the next concreting position is to be carried out. The two Main Girders are moved independently or simultaneously to the next span.

A typical construction cycle with the underslung MSS.. ..

The two girders are moved transversely, joined in the middle of the Transverse Beam system and raised again.

A typical construction cycle with the underslung MSS.. ..

The Internal Formwork will be goes out by man power from manhole and install by crane after installation of reinforcement has been completed.

Manhole of top slab

A typical construction cycle with the underslung MSS..


The MSS is now raised by means of the front Main Jacks (located on the supporting brackets) as well as the rear pair of main jacks, transferring the loads via the webs of the superstructure.

As soon as the External Formwork is adjusted, reinforcement & ducts incl. cables will be laid out. The internal Formwork will be relocated and the new span can be poured.


A typical construction cycle with the underslung MSS - 3D Image

SUPPORTING BRACKETS LAUNCHING WAGON


SUPPORTING BRACKETS LAUNCHING WAGON MAIN GIRDER


SUPPORTING BRACKETS LAUNCHING WAGON MAIN GIRDER TRANSVERSE BEAM EXTERNAL FORMWORK







Step by step erection Assembly of MaingirderThe Maingirder has to be assembled on leveled wooden or steel supports, leaving a min. of 1 meter clearance to the ground to be able to install the bottom and pushing rail connection plates. Note: Complete assembly of Maingirder depends on crane capacity for lifting at site. Location of assembly must be planned according to lifting procedure and positioning of cranes

Step by step erection Assembly of MaingirderIf crane capacity for one step lifting can not be obtained, the Maingirder must be assembled section by section. Starting from a Supporting Bracket using temporary support towers, the Maingirder is assembled towards the next Supporting Bracket. JV used method.

Step by step erection Assembly and installation of Supporting BracketsEach Bracket is prepreassembled on the ground. If 2 cranes are available, the Brackets can be installed simultaneously.

Step by step erection Assembly and installation of Supporting Brackets2-Step installation of Supporting Brackets

One part of the Bracket is lifted and a temporary assembly beam is installed to hold the Bracket in position. Then the second Bracket is lifted and the Dywidag bars are installed. JV used method.

Step by step erection Lifting of Maingirder in one stepEach Maingirder is lifted in one heavy synchronized lift using 2 cranes connected to the Main Lifting Lugs

Depending on design of Main Lifting Lugs: Transverse Beams, Counterweights (some MSS are equipped with) or even Front and Rear Noses could be assembled on the ground and lifted together in one lift.

Step by step erection Lifting of Maingirder in one stepAfter both Maingirders have been placed on the Launching Wagons, installation of Transverse Beams and Platforms can start

Note: Make sure counteracting bearing plates are now installed!

Step by step erectionAfter Transverse Beams and Platforms are installed, both Maingirders are brought into position by side launching and the Transverse Beam center connections are locked with Dywidag bars. The system is now ready for installation of Noses and Bottom Slab.

Step by step erectionThe Bottom Slab is installed on the Adjustable Supports located at the top chord of the Transverse Beams. The Bottom Slab sections are supported and connected to each other by overlapping flange plates.

If wooden formwork is used, the timber on which later the Plywood will be fixed can be installed on the ground. JV used metal form

Step by step erectionNow the MSS is raised by the Main Jacks approx. 200mm into concreting position.

During lifting and lowering, the Mechanical Locking Ring is moved at steps of approx. 30 - 50mm. This as a safety prepre-caution in case of any hydraulic failure

Step by step erectionNow the transverse slope as well as cambering is adjusted by use of the Adjustable Supports.

The Web formwork can now be installed and secured by the Supporting Spindles. Curvature is adjusted as well as correct angle. Timber and / or Plywood has been installed on the ground.

Step by step erectionSimultaneously, installation of Top Slab Wing formwork starts.

Step by step erectionExternal Web and Wing formwork are supported by adjustable spindles to allow exact adjustment of transverse cross-fall, cambering crossand curvature.

Assembly continues with installation of Walkways for safe and ease access to all working areas

Step by step erectionThe wooden formwork is supported at the Bottom Slab panels and pierhead.

Formwork is completed by installation of Plywood according to required shape of designed pierhead / bearing area.

Step by step erectionAt the front, the MSS is now ready for installation of re-enforcement rebars and stressing equipment. ReRe-enforcement can be installed completely - from Bottom Slab up to the Web Top Slab

Step by step erection

Concrete spacer

Installation of internal formwork. The frame of internal formwork is put on concrete spacer.

Step by step erectionNow the remaining re-enforcement reat top slab is completed.

Preparation for concreteShuttering at the Web, Top Slab and Bottom Slab is now executed. Stressing anchors, grouting tubes and all remaining items are now installed.

Pouring concrete

Special pouring windows, located on top panels of Internal Formwork allow the concrete to be distributed throughout the Bottom Slab. When the Bottom Slab is poured finish, the windows are closed.

Pouring concreteSequence of concreting transverse direction : The concreting works has to be done symmetrically about centre bridge. The Top Slab must be cast at side top panels before/ at the same time as the web, to avoid uplift of Internal Formwork.

Sequence of concreting longitudinal direction : The concreting works has to start from the piers and progressively towards mid-span. mid-

Pouring concrete

Preparation for LaunchingAfter pre-stressing has been preexecuted, the MSS is prepared to be lowered on to the Launching Wagon again. At the rear, the Dywidag connections to old concrete are disconnected. Shuttering at front is removed. The system is then lowered and counter acting bearing plates are installed.

Launching

The MSS is then launched to the next span. Unless special notes are given in the operational manual, the two halves can be launched independently.

LaunchingThe Noses will support and guide the Maingirder on to the next Bracket. Noses can be adjusted sideways for launching in curves.

Minor adjustments in elevation can be made as well, using a special device located in the middle of the two Nose sections.

LaunchingWhen the exact position is reached, the system is side launched and connected again.

After the hydraulic jacks are in place, the system is then lifted into concreting position again. Rear External Formwork is suspended to the old concrete by Dywidag bars.

Launching

The MSS is now ready for the next cycle. Installation of rereenforcement can start again.

Thanh Tri Bridge

Documents

Transcript of Thanh Tri Bridge