SUMMARY 7-8/2003

Prefabricated girders represent one of the basic forms of technology applied in bridge construction. The rapid advancement of automobile transportation following the Second World War demanded an acceleration of the construction of new roads and motorways, as well as the reconstruction of existing structures. The first bridges constructed from pre-fabricated girders, corresponding to the demands for the quick and easy construction of bridge structures, were already being built in the 1950s.
However, the period of the greatest expansion of this technology occurred in the 1960-80s, when it was the most frequently designed and mass constructed load-bearing structure for bridges of small and medium-sized dimensions.

During floods the operations at the individual reservoir stations are managed from the water management control centre of the Vltava River Basin - Povodí, a state-owned enterprise. Input information for operating the cascades comes from both the Czech Hydrometeorological Institute and from a network of automatic river gauging stations with teletransmitters set up along the river.
Over the course of the past several years a process of gradual modernisation of the water management control centre has been underway. On-line data on the actual flow through the power facilities, and on the water levels along the entire cascade, are acquired from the cooperative involvement of the power and water control centres. The data from the automatic river gauging stations and the data derived from meteorological and hydrological forecasting models, processed by the Czech Hydrometeorological Institute, and the output of radar installations all serve as the basis for carrying out operations at the individual reservoir stations. The information systems, data transfers, communications systems, and other aspects have all been updated.
Despite all these facilities it is necessary to emphasis that there are only limited possibilities for influencing the course of flooding on the lower Vltava Basin. Information of a sufficiently accurate nature on expected precipitation levels can only be provided a maximum of three days prior to occurrence, with a reliable calculation of the levels of rainfall only after its occurrence. The time horizon for the flow of rainfall occurring in the most distant region of the river basin through to the arrival of the flood wave in Prague is maximally three days, which is not much time for implementing the necessary anti-flood measures. One significant problem is the fact that for the implementation of necessary measures in Prague (relocating boats to protected harbours, putting up the mobile anti-flood walls, and eventually even the evacuation of parts of the population) it is not possible shortly prior to the arrival of the flood wave to initiate any fundamental pre-discharge of the reservoirs. Another important factor in managing the course of the flood situation on the lower Vltava Basin is the fact that the Vltava cascades only impact the water yield from a part of the catchment. The water yield from almost one half of the territory cannot be more substantially influenced owing to the absence of any reservoirs with larger retention effects on the Beroun River and the Sázava River in particular.

The article examines the roofs and the trusses of the cloister of the Church of St. Jan Nepomucký, which was repaired at the end of the 1990s. The Church of St. Jan Nepomucký at Zelená Hora in Žďár nad Sázavou, which in 1994 was included in the UNESCO World Heritage List, is the masterpiece of Jan Blažej Santini.
The new components of concrete constructions mentioned in this article include:
Balcony insulation elements, sliding laths, reinforcement connectors, and connecting rods. The church was built in 1719-1722, and the site was repaired and completed in the 1760s. The cloister, which surrounds the church, is comprised of five four-sided gates (only three of which are open), five five-sided chapels, and the ten galleries of the cloister, the angled frames of each of which, tracing a circular ground plan, extend back to the outer side of the structure to form a sharp point.