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| Highest bridge in Latin America with PERI systems  The Baluarte Bridge ranks among the most outstanding infrastructure projects which have ever been realised in Mexico. PERI planned and supplied a cost-effective formwork and scaffolding concept for the construction of the different bridge piers. The ACS self-climbing formwork used for the pylons allows crane-independent climbing in all weather conditions which accelerates construction progress quite considerably. The 1,124 m long Puente Baluarte will eventually span a ravine with a depth of 390 m. After completion in the year 2012, the structure's dimensions will mean that the bridge will actually be ranked as the world's third highest. The main span of the cable-stayed bridge is 520 m. Nine bridge piers and two pylons support the 20 m wide superstructure.P5 is the highest pylon and reaches a height of 169 m, the topmost point of its opposite P6 ends 13 m below this. The largest cross section at the foot of the pylon measures 18.00 m x 8.56 m. In the carriageway centre, it widens to about 31.30 m – the piers then taper upwards and have dimensions of 8.00 m x 4.10 m at the top. The pylon legs are not only inclined but also feature different cross-sections along the complete height. For the construction of this complex geometry, PERI developed a self climbing solution on the basis of the ACS system. The ACS V (V = variable) was used for the forward and reverse inclined external walls. The platforms of this climbing scaffold can be continuously adjusted to match the angle of inclination which means that horizontal working levels are always available. This facilitates a comfortable working environment and also provides the maximum level of safety security for site personnel. The self-climbing technology accelerates working procedures due to the fact that the system is neither crane nor weather dependent. The construction which was designed to accommodate very high wind loads and the patented control process of the climbing mechanism are special features of the extensive safety concept. The working platforms are very stable and allow the storage of large quantities of materials, e.g. reinforcement items. The extremely variable VARIO GT 24 girder wall formwork is being used on the climbing scaffold. The PERI concept permits the construction site team to quickly adapt the formwork to suit the requirements of each concreting section and thus accurately construct the pylons. At the same time, the proven PERI Fin-Ply formlining guarantees high quality surface finishes with which around 50 to 70 uses are possible. Construction of the pylons is carried out using a total of 46 or 49 concreting sections with variable concreting heights of between 3.28 m and 3.90 m. The foreland piers have been designed as double piers. They vary – according to the shape of the terrain – in their height up to a maximum of 145 m. These piers were also constructed using VARIO GT 24 girder wall formwork. The large majority of the surfaces could be formed with standard panel formwork whilst for the tight inner areas, PERI planned project-specific elements. These were accurately adapted and pre-mounted to match geometrical and static requirements as well as being delivered on a just-in-time basis to the construction site. The assembly of the 5.10 m high elements with only four SRZ waler lines allows a maximum fresh concrete pressure of 50 kN/m˛ and thus the required concreting speed of 2.00 m/h. On the pier exteriors, CB 240 climbing brackets support the VARIO elements. With the framework brackets, large-sized wall formwork can be supported. They ensure simple handling, fast concreting cycles and problem-free adjustment to suit the various structural designs. The 2.40 m wide platform lining is positioned over the brackets and, together with the formwork carriage, forms an even surface without any tripping hazards. In the internal area of the double piers, the construction crew uses BR platforms for supporting the formwork elements. These shaft platforms are used where conventional climbing scaffold is not suitable due to space limitations. In each case, the units formed from formwork and climbing brackets or platforms can be moved easily and quickly with the crane. Cross members with a height of 4.00 m connect the supports of the double piers. TRIO panel formwork forms the side formwork and MULTIFLEX slab formwork serves to shape the underside of the members. High load-bearing GT 24 formwork girders are used as the main and cross beams. Due to the enormous loads, the girder spacing was limited to only 20 cm which meant any deflections of the formlining could be minimized. A PERI UP Rosett scaffold construction carries the member formwork during construction. The modular design of the scaffolding system allows optimal adaptability in order to handle the generated loads: in the cantilevered area of the working platforms, PERI UP is assembled using a 1.50 m x 1.50 m basic grid while UBS shoring braces serve to brace the construction. Directly under the member formwork, 25 cm walers are installed. This reduction of the grid dimensions increases the load bearing capacity of the scaffold in the area of high loads. For the respective 13.50 m higher positioned members, the PERI UP shoring is placed on the previously installed cross beams. Steel profiles carry the cantilevered areas. The Puente Baluarte is being constructed in a mountainous region which is very difficult to access and is situated directly on the border that separates the states of Durango and Sinaloa. It is part of a new highway development in north-western Mexico which will form the single fast connection between the Pacific coast and the interior. The new route runs virtually parallel to an extremely narrow existing road which is famously known as the "Devil's Backbone": this road, which is not much wider than a single track, runs along the jagged peaks of the western margin of the Sierra Madre and is extremely risky to negotiate with its apparently endless, very tight bends. The new highway will not only be considerably safer but will also basically halve the required journey time between the towns of Durango und Mazatlán. The Baluarte river forms the border between the two states of Sinaloa and Durango – the 390 m deep ravine is by far the most challenging hurdle along the whole distance and is spanned by the Puente Baluarte cable-stayed bridge. The route also features several reinforced concrete beam bridges including the Baluarte bridge with eight of these structures being over 90 m high. In addition, 63 tunnels will be constructed as part of the new development. write your comments about the article :: © 2010 Construction News :: home page |