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Recent Reinforced and Prestressed Concrete Bridges in Italy

In recent years, the need for the modernization of industry and the infrastructural system has propelled the growth of the Italian construction industry. In this paper, some basic data will be provided about the production and consumption of raw
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  CBM-CI – Int. Workshop, Karachi, Pakistan Engr. S.N. Vanikar and Dr. C.H. Goodspeed ITALY – RECENT REINFORCED AND PRESTRESSED CONCRETE BRIDGES IN ITALY Dr. Pier Giorgio Malerba Dept. of Structural Engineering Politecnico di Milano, Milan ITALY   ABSTRACT: In recent years, the need for the modernization of industry and the infrastructural system has propelled the growth of the Italian construction industry. In this  paper, some basic data will be provided about the production and consumption of raw materials connected with the building industry, and the different sectors in which the country is now engaged will be presented. In a second part, the subjects on which the most advanced research and projects are currently focusing will be briefly described. The paper closes with an overview of some recently completed bridges. 1.   DEMOGRAPHICS AND THE CONSTRUCTION INDUSTRY Italy covers an area of 301,338 km 2  (116.347 sq mi), with a population of 58,781,711 people and a population density of 195 inhabitants per km 2  (505 inhabitants/sq mi). Recent years have seen growing immigration, mainly from Eastern Europe, Africa, Asia, and South America. In 2006, a total of 2,227,567 immigrants entered Italy. Many of these people are employed in the construction industry. The production of raw materials for the construction industry ( Tables 1 and 2)  is proportional to the geography and economy of the country. Estimated annual world production of plain steel is 1,243,839 tonnes (1,224,251 tons). Estimated annual world production of cement 2,290 million tonnes (2,253 million tons). Table 1 Annual production in percentage of world production of plain steel in 2006.   Italy Europe East Europe and CIS North America South America Africa Middle East Asia 2.54 15.96 12.56 10.57 3.64 1.50 1.24 53.84  Table 2 Annual production in percentage of world production of cement in 2006.   Italy Europe Other Europe and CISUSA Other America Africa Asia 2.1 10.8 6.0 4.3 6.1 4.2 68.6  CBM-CI – Int. Workshop, Karachi, Pakistan Engr. S.N. Vanikar and Dr. C.H. Goodspeed 2. RECENT ACHIEVEMENTS OF THE CONSTRUCTION INDUSTRY In recent years Italy has seen a considerable increase in the construction industry, mainly due to the need for modernization of roads, railways, harbors, airports and industrial plants [1]. Resources were assigned to the restoration of historical buildings such as churches and theatres. As in other countries, special attention is being paid to the development of infrastructure. Considering the conformation of the Italian peninsula, the greatest efforts are in making the connection between North and South faster and safer, thanks to the implementation of a vast program of building and/or improvement of roads and railways. 2.1 Railways The largest project under construction is the high-speed railway line that runs from Milan to  Naples, passing through Bologna, Florence, and Rome in between ( Figure 2.1 ). A high-speed railway between Turin and Milan is nearing completion, while the connections  between France and Italy and between Milan and Venice towards Slovenia are still at the  project stage. Figure 2.1 A high-speed railway line runs from Milan to Naples, passing through Bologna, Florence, and Rome.    CBM-CI – Int. Workshop, Karachi, Pakistan Engr. S.N. Vanikar and Dr. C.H. Goodspeed Considering that the majority of the territory is mountainous and that flat areas are densely  populated, building these infrastructures has involved solving complex problems posed by interferences. The need to reduce the impact on the environment, and to keep the track as straight as possible to allow the trains to reach a projected speed of 300 km/h (186.3 mi/h)  pose many challenges. Developing long stretches of the track on viaducts allowed builders to meet part of these project requirements, but newly designed, high performance precast structures had to be realized [2], [3], [4]. Together with a series of medium size bridges, the new high-speed tracks brought to the construction some unique structures that have significant relevance from an engineering point of view. Among those, the cable stayed viaduct on the river Po, which is designed to bear the high loads required by railway traffic (max live load per track: 150 kN/m; max load per axle: 250 kN), passes over the river with three spans of 104 – 192 – 104 m (341 – 627 – 341 ft) [5]. The most challenging element of the link is the suspended bridge over the Messina Strait. Intended to provide a stable connection between Sicily and continental Italy for both car and train traffic, it will have a steel deck sustained by two 382.6 m (1,255.23 ft) high steel pylons, and it will pass over the strait in three spans of 183 – 3300 – 183 m (600.39 – 10,826.77 – 600.39 ft) [6], [7], [8]. The  preliminary project was completed with the definition of performance requirements. The development of the project was then assigned to a firm chosen among those that responded to an international call for bids. At this time, the economic state of the country is such that the government has decided to direct all available resources to the completion of works in  progress, causing a temporary halt to the Messina Strait Bridge project. 2.2 Railway Stations The transformation of the railway network into a high-speed service and the resulting increase in the number of passengers have necessitated extensive adaptations of major existing stations (such as the Milan Central and Turin Porta Nuova stations) as well as the  building of new terminals. The latter have been designed to make the critical phases of stopping and departure of the trains as short as possible, thus contributing to reducing the overall travel duration. Among others, two important stations are currently nearing completion in Florence (architecture by Foster and Partners, London; engineering by Ove Arup, London, Milan) and in Rome (architecture by Gruppo Desideri, Majowiecki, Gruttadauria et al., Rome). 2.3 Road Infrastructure The most extensive project is the completion of the new Salerno – Reggio Calabria highway. The project has faced severe problems due to the narrowness of the area suitable for building. Moreover, the new road track is adjacent to the existing one and partially overlaps it, which results in heavy interference between building activities and regular traffic. Work is in  progress on the Milan – Venice highway, in the stretch between Milan and Bergamo, where the carriageway is being widened, and at the Venice Mestre Junction. Sometimes the highways intersect the new railway network, like in Reggio Emilia, where a large steel arch  bridge designed by Santiago Calatrava has just been completed. Relevant interventions have also been carried out in the areas around some of the most important towns, where new  beltways, from which centre-bound roads depart, have been built. In the design phase of these infrastructures, particular attention was paid to environmental compatibility. This  CBM-CI – Int. Workshop, Karachi, Pakistan Engr. S.N. Vanikar and Dr. C.H. Goodspeed resulted in a close cooperation between architects and engineers intended to merge functional needs and aesthetic outcomes. 2.4 Airports In the last few years, the implementation of a plan for updating Italian airports led to the reconfiguration of some airports as well as the construction of new airports in several towns (Milan Malpensa 2000, Venice Tessera, Cagliari, Bari, Catania, Alghero). The Milan Malpensa Airport is particularly important as it is intended to serve as a new international hub for northern Italy. The project started in the early 1990s in an area adjacent to the existing Malpensa airport, and now operates as a charter terminal. The first phase (after the completion of which the new airport was fully operational) was the building of the passenger terminal, runways, main road network (with the two curve cable stayed bridges that have by now become a landmark) and of the warehouses of the vast Cargo building. In a second  phase, a new airplane hangar was added. Currently the northern wing of the terminal is being completed, and a link intended to connect the heads of the two main runways is under construction. It includes two viaducts that pass over the in-trench Ferrovie Nord railway track that connects Malpensa to Milan. The compound has been conceived to give the impression of two arms (the lateral wings of the passenger terminal). In front of the  passenger terminal, a lower building hosts the car parks and the railway station. The body of a hotel, currently at design stage, will emerge from this structure, completing the overall construction of the airport. 2.5 Harbors and Coastal Safeguards Because of increasing trade, the Italian peninsula, placed at the centre of the Mediterranean Sea, has seen the adaptation of many harbor facilities and the construction of new ones, many of which are dedicated to leisure craft. Among these, the new Trieste 7 th  dock is an important addition to the harbor facilities. The dock, 800 m (2,625 ft) long and 150 m (492 ft) wide, is made up of square plates with 9.9 m (32.48 ft) long sides. It lies on centrifuged, monolithic  piles that were subsequently filled with reinforced concrete up to fixed joints. Concerning coastal safeguards, the most peculiar project is certainly the system of mobile barriers for the defense of the Venice lagoon from high tides (MOSE). The mobile barriers are made up of lines of steel caissons, which in normal tide conditions are full of water and lie flat in their concrete housings. When tides exceeding the safeguarding level are forecast, an emission of compressed air empties the caissons, causing the bulkheads to pivot around a pin anchored to the housing cases until they emerge, forming a barrier that temporarily isolates the lagoon from the sea, thereby safeguarding Venice from being flooded. Some preparatory works have already started, but the project is facing many difficulties, including environmentalists’  protests. 2.6 Theatres and Preservation of the Historical Heritage Italy has an important artistic and musical tradition. Relevant financial resources have been employed for the restoration of ancient theatres (Theatre La Fenice in Venice, the New Scala Theatre in Milan) and for the building of new ones (such as the Parco della Musica Auditorium in Rome, architecture by Renzo Piano Building Workshop). The work on the  New Scala Theatre involved the demolition of the existing scenic tower and the building of a  CBM-CI – Int. Workshop, Karachi, Pakistan Engr. S.N. Vanikar and Dr. C.H. Goodspeed new one where high-tech stage machinery has been housed. The new scenic tower starts at 18.41 m (60.40 ft) below street level and stretches 33 m (108.29 ft) above street level, for a total height of 56.51 m (169.00 ft) and a cross section of 650 m 2 (6,996 sq ft.) [9] [10]. One of the most relevant innovations is the fact that the stage, which is made up of segments which can move vertically, can be withdrawn and substituted by a second deck projecting from a lateral body until it rests on the opposite wall. This allows the staging of many different scenes at a time. Behind the scenic tower and along one side of the main building there are rehearsal rooms, workshops, and offices. An elliptic structure that merges coherently with the original architectures rises from the lateral body. As important as the erection of new buildings and the introduction of advanced technology was the restoration of the monumental part of the hall. Given the international fame of the Scala Theatre as an opera hall, special attention was paid to the acoustics [11]. 3. RESEARCH ACTIVITIES IN CIVIL ENGINEERING Recent studies have been and are being conducted on a wide range of subjects, including the mechanical behavior of materials (high strength, fiber reinforced and self-compacting concretes, special and recycled aggregates, steels); the assessment of corrosion protection by means of structural modelling [14]; safety theories; seismic engineering; construction techniques (pre-stressing; prefabrication); quality control; evaluation and rehabilitation of existing buildings; job management; and problems of environmental sustainability in the  production process. The results of these studies are condensed into a set of technical recommendations on specific topics and in contributions to the Model Code, which has already appeared in several editions and represents an advanced reference for operational structural codes. The research activities contribute to innovations in design and construction practice for new projects as well as to  preserving the historical and artistic inheritance of the country. Such profitable cooperation has resulted in the recent revision of the Italian Standards. 4. SOME STRUCTURES – RECENTLY COMPLETED Some of the recently completed bridges in Italy are described below. The choice criteria are subjective, and the descriptions of these bridges are not claimed to be comprehensive. 4.1 The “Malpensa 2000” Air Terminal Cable Stayed Viaducts General Data: Client: S.E.A. Soc. Esercizi Aeroportuali, Milan (Italy). Bridge Designer: Francesco Martinez y Cabrera. Works Management: Consorzio Malpensa Construction. Contractor: Impresa Pessina Costruzioni S.p.A., Milan. Completed in 1997 [12]. The access to and from the departure area of the terminal is provided by two twin cable stayed bridges ( Figure. 4.1 a, b ). The road track is uphill and curves such that the deck course is shaped like a circular helix. It is comprised of two 70.00 m (230 ft) spans for a total length of 140.00 m (459 ft). The post-tensioned concrete deck is 1.35 m (4.43 ft) deep and
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