Glass rings used to be one of the most common jewellery types in the 10th-13th centuries in Central Europe, especially Silesia. The popularity of this type of decoration in this area could indicate its local origin. The chemical composition of the glass seems to confirm this theory. The Silesian glass rings analysed in this paper were made of high-lead alkaline and nonalkaline glass or of lead-ash glass. There was also a close relationship between the colour of the finished products and the chemical composition of the glass. This provides new data for the study of the problem of production and distribution of glass jewellery in Central Europe.
The Centennial Hall, a reinforced concrete structure with an auditorium for 10 000 people, was opened in Wrocław, Poland (then Breslau, Germany)
Short historical outline of massive domesThe most famous building with a roof constructed as a coffered concrete dome is the 2000-year-old Pantheon in Rome, commissioned by Marcus Agrippa in 27 BC and rebuilt by Emperor Hadrian in about 126 AD [1]. During its history, the building had various functions and was eventually turned into a church. It is a great structure with a central opening (oculus) at the crown and a lower ring 43.3 m in diameter. The thickness of the dome varies from 6.4 m at its base to 1.2 m at the level of the oculus [2]. The stresses in the dome were reduced by using lightweight aggregate, e.g. pieces of pumice in higher layers, which decreased the density [3]. This reduced the weight of the roof, as did the coffered structure of the dome ( (Fig. 2), erected under Justinian between AD 532 and 537, is one of the greatest achievements of Byzantine culture and has undergone a turbulent history, also during its construction. In May 558, following the earthquakes of August 553 and December 557, parts of the central dome and its supporting structure collapsed [5]. Between 558 and 562 a new modified design was introduced, resulting in the dome we see today.The next large dome structures were built in Europe during the Renaissance [7]; Florence Cathedral (the largest dome since antiquity, with a diameter of 44 m) and St. Peter's Basilica in Rome (on the left in Fig. 3), which has a dome with an inside diameter of 42.7 m [8]. This is a double shell structure made of bricks and travertine blocks held together with lime mortar, stiffened by 16 ribs and supported by a cylindrical structure stabilized by 16 buttresses [8]. During the construction of the dome, carried out in 1589-1592 by Giacomo della Porta, three iron chains were built into the internal shell, and in 1590 two additional hoops were added at the base of the lantern [9].
<p>Highway ring road of Wrocław is a very important part of an urban communication network which is now under modernization work. It will connect the existing A4 highway with the S8 expressway being under construction. The ring road is 26.765 km long. Forty bridge structures were designed along or over it. Total length of highway bridges and viaducts is more than 6 km, that is equivalent to 22% of the whole route.</p>
<p>The longest bridge is a concrete cable-stayed structure over the Odra River. The river flows in its main bed, while inland navigation uses additional channel with two locks. There is an island located between the river and the channel. The planned bridge is 1742 m long and consists of: south flyover 610 m long with continuous eleven span prestressed concrete box structure; main bridge 612 m long with two separate decks connected to a single concrete H-shaped pylon; north flyover 520 m long with continuous girders made of prestressed concrete.</p>
<p>The Warta is a medium size river in central Poland. The project of the Warta river crossing was connected with the project of the town ring road of Konin. The crossing was divided into four independent structures: three flyovers E5, E7, E8 and the main bridge. All structures were designed for two roads.</p>
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