Pelješac Bridge

The Pelješac Bridge is designated a project of strategic importance for the Republic of Croatia, assessed as "one of the construction projects that will mark our generation". The main goal of constructing the Pelješac Bridge is to connect the south of Croatia with the rest of the country's territory. Croatia is finally "whole" after over three centuries. The bridge's opening is an event comparable only to the most extraordinary events in Croatia, such as the gaining of national independence. The INSTITUT IGH, JSC, provided technical supervision and quality control of the construction of the Pelješac Bridge, together with partners. The value of the project's construction was 274 million EUR (without VAT), and it was co-financed from EU funding with a non-refundable 85% of the funds. The development of the bridge, 2.4 km long and 55 m high with four traffic lanes, took 1277 days and was finished with the opening ceremony on July 26, 2022.

The team of experts from the INSTITUT IGH, JSC consisted of 25 people (supervising engineers, supervising associates, and quality control experts) led by engineer Đuro Mihalić, B.Sc. It was an extremely demanding venture made even more difficult by the challenges caused by the Covid 19 virus pandemic. In the Laboratory for materials and structures of the INSTITUT IGH, JSC, extensive tests of various concrete compositions were carried out to meet the conditions of the project. As a building with special construction conditions, a minimum of 4 hours of concrete consistency maintenance was set, which also required additional attention during design. The testing program included the production of concrete compositions with different proportions of mineral additives to cement, such as slag, fly ash and silica dust. In addition to meeting the criteria of mechanical characteristics of concrete, particular emphasis is placed on determining the durable properties of concrete. Concrete permeability tests were performed - several chloride diffusion methods, gas permeability, capillary absorption, microscopic pore analysis, and freezing and thawing cycles with de-icing salt. Long-term deformation tests due to shrinkage and creep were also carried out.

It is an exceptional bridge in every respect. With a length of L=2404 m, the bridge is one of the most demanding bridges in the world, both from the point of view of the project's complexity and demanding and complex execution. The concept of the bridge is structurally inventive. It is an integral hybrid construction with a hybrid span construction. The base segments are concrete, and the rest is a steel crates. The suspended span structure and the pylons are elastically fastened to the columns so that the bridge in the central part (75%) of the total length is a frame structure without bearings (good for earthquakes and wind). The bridge location is in an area of high seismic activity. According to current norms, the bridge classifies in the highest importance class IV and bridge type C, which means that it is a bridge of exceptional importance for maintaining communication even after an earthquake, with a service life of >= 100 years. The peak acceleration of the foundation soil is amax=0.34 g, i.e. the required calculated acceleration of Eamax=0.54 g. (Zagreb M 5.5 amax=0.22 g). The compact load-bearing rock is located more than 80 m from the seabed, so including the average sea depth of 27 m, it requires a deep foundation on driven steel piles up to 130 m long (belt tube-cathedral tower). Also, the bridge is in an area of intense and gusty winds with peak wind speeds exceeding 180 km/h. The calculation was made by simulation using Computational Fluid Dynamics and confirmed by model testing in a wind tunnel. The Pelješac bridge is a suspension (extrados) with six pylons and five openings. The total length of the bridge is 2404 m, and it has a total of 13 spans (2x84m, 4x108m, 2x189.5m, 5x285m), the height of the pylon is 98 m, and its width is 22.5 m.