Cost-effective forming and shoring of bridges with PERI modular systems

Motorway Bridge D1, Považská Bystrica, Slovakia

For the construction of the 767-metre long motorway bridge in the area of the "Centrum“ D1 motorway junction, PERI´s Slovakian engineers developed a formwork and scaffolding solution which perfectly suited the on-site requirements. This resulted from the fact that PERI provides one-source formwork, scaffold and engineering services whereby the bridge formwork and falsework were optimally matched. In addition, this means that integrated, load-optimized system solutions can be achieved along with the guarantee of smooth and efficient construction progress.

Standardised modular system
Planning and execution are based as far as possible on rentable PERI modular construction systems – the PERI UP scaffolding system and VARIOKIT engineering construction kit. Construction of the hollow box cross-sections for the superstructure is carried out using PERI UP falsework. The external web formwork together with the cantilever formwork have been created by means of variable latticed frameworks using VARIOKIT system components – so-called raised formwork units.

The demands placed on the construction crew and the selected formwork solution are particularly high in this case because the bridge cross-sections as well as its longitudinal and lateral inclinations continuously change. At the same time, a junction point has to be taken into consideration whereby two separate superstructures merge to form one distinct bridge structure. In the process, single and twin-spaced hollow box cross-sections with variable superstructure widths are to be cost-effectively constructed. This requires a high degree of flexibility and variability of the PERI system components used in this project.

Lightweight shoring for heavy loads
The PERI UP supporting scaffold transfers the loads arising during construction of the superstructure, at heights of between 13 and 15 metres, safely and reliably into the ground. Through its modular structure and metric grid arrangement, the load-bearing system can be optimally adapted to deal with all forces. With 150, 75 and the short 25-centimetre standards, the individual load-bearing capacities of 40 kN per leg can be combined to deal with higher loads - and can be virtually multiplied at will - in both lateral and longitudinal directions, and thus being able to easily adapt to each particular load situation. Even for concentrated load points, as found in the web areas, several standards can be bundled together using system components. Compared to system-free working with tubes and couplers, the assembly team achieved considerable time and safety advantages. In connection with the high ledger rigidity of the PERI UP scaffold nodes and the easy to mount system diagonals, the scaffolding sections remain sufficiently stable in all situations. All occuring vertical and horizontal loads can be safely transferred into the ground in order that the dimensionally-accurate specifications for the formwork assembly can be reliably maintained.

PERI UP has been type-tested up to a height of almost 22 metres and can be used - in addition to the use as space stand - also as column framework unit and as shoring tower. The available type test saves on time-consuming static calculations for standard applications and can be referred to for individual project static calculations as a basis for the design. Furthermore, project-specific construction drawings in combination with the assembly instructions are also part of the PERI range of services. These provide site personnel with all required detailed information including individual assembly steps.

With the PERI UP scaffold system, a wide range of scaffolding tasks can be solved using just one system. Moreover, the required access sections are also integrated into the falsework itself. PERI UP staircase units allow site personnel to reach both the working and support level as well as the concreting and carriageway level. The alternating staircase units are based on a grid dimension of 3.00 x 1.50 metres thus optimally adapting to the shoring dimensions. The multiple use of the scaffold components - standards and ledgers - for different areas of application facilitates site assembly and logistics operations.

VARIOKIT engineering construction kit
The hollow box superstructure is being realised in two casting segments with the help of VARIOKIT raised formwork units. In the first cycle, the bottom plate complete with webs is formed and concreted whilst the carriageway slab and cantilevers are constructed in the second cycle. GT 24 formwork girders, SRU steel walers and SLS heavy-duty spindles have been accurately adapted to the structure´s geometry and falsework adapted, as well as having hinged and friction-locked connections with articulated walers and universal couplings, resulting in the most ideally-suited unit for this purpose. Loads from the working and concreting operations can thus be safely carried into the substructure and reliably transferred downwards.

Rational construction progress
The span width is 34 metres which also represents the length of each individual concreting cycle. For ensuring optimal building progress, the contractor had sufficient scaffold material available for three complete construction phases. While two cycles are always completely scaffolded, the third set of materials is gradually dismantled, transported to and re-assembled in the next section. Due to the different conditions and the large distances between each section, the site crew have dispensed with moving the large area scaffold units by crane. Therefore, the assembly and safety advantages of PERI UP play an extremely important role: low individual weights, as well as assembling the ledgers from a safe and secure position, ensure fast and safe working procedures. VARIOKIT raised formwork units have been designed so that they can be moved suspended together with the crane, and then be easily adapted to the new structure geometry by means of only a few working steps.

Closing another gap in the Slovakian road network
The D1 motorway travels across Slovakia, between the Austrian state border in the west and Ukraine in the east. With a planned overall length of 500 kilometres, six sections totalling almost 300 kilometres have been opened so far to traffic. Closing the ten kilometre long gap between Sverepec and Vrtižer, close to the northern Slovak city of Považská Bystrica, is currently under construction. The official opening is planned for the end of 2010.

Contractors: Bögl a Krýsl, k.s., Prešov
Field Service: PERI spol. s r.o., Slovak Republic

PERI Systems in Use:
- PERI UP Rosett Column Framework Unit
- PERI UP Stair Tower
- VARIOKIT

PERI was founded in 1969 and is today one of the leading providers of formwork and scaffolding systems. Along with the headquarters in Weißenhorn, Germany, the company has 46 international subsidiaries and 100 stock yards around the world. The company has over 5400 employees of which 850 are engineers. 2008 revenues was 1,220 million Euros.

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This release was published on openPR.