Zlatko Šavor

Cable Vibrations at Dubrovnik Bridge

The only cable-stayed bridge in Croatia, the Dubrovnik bridge, was opened for traffic in 2002. The main cable-stayed bridge with composite superstructure is jointed in span to the prestressed concrete approach bridge by a hinge-type connection. The bridge has experienced vibrations of cable stays under certain wind conditions, as with many other cable-stayed bridges around the world. After a short review of results of wind tunnel tests and various numerical analyses, field observations of cable-stay vibrations are highlighted. Only after extremely violent movements of cable stays and the superstructure under a heavy, damp snowstorm occurred, resulting in substantial damage, was it decided to apply vibration mitigation measures. Adjustable cable dampers, based on the latest MagnetoRheological (MR) technology, were installed on the bridge to raise low structural damping of the most affected cable stays.

Report: Extreme Wind and Salt Influence on Adriatic Bridges

This paper presents an overview of maintenance and repair of some large Croatian arch bridges built in a marine environment, characterised by strong winds. The performance in service of older bridges cannot be deemed satisfactory. Structural defects were found at an early age and hence cannot be blamed primarily on the environment, but are attributed also to conceptual design and errors and negligence on site. Therefore, new bridges are being designed and built utilizing new durability concepts.

Procedures for Reliability Assessment of Existing Bridges

Budući da su mnogi mostovi u svijetu davno izgrađeni, a iz društvenih i ekonomskih razloga potrebno ih je i dalje upotrebljavati, nužno je provesti ocjenjivanje njihove pouzdanosti. U radu su opisana najnovija istraživanja u svezi s tom danas vrlo aktualnom problematikom. Predložene napredne proračunske metode za ocjenjivanje postojećih mostova u više koraka utemeljene su na probabilističkoj teoriji pouzdanosti, a razmatraju se karakteristična ispitivanja materijala, ocjene stanja i zalihe nosivosti konstrukcijskog sustava i stvarna prometna opterećenja. Dan je pregled inozemnih normi i napravljena njihova usporedba.Veliki broj mostova u svijetu davno je izgrađen, te zbog drustvenih i ekonomskih potreba njihove daljnje upotrebe treba neophodno provesti ocjenjivanje njihove pouzdanosti. U radu je dan pregled najnovijih istraživanja u svezi te danas vrlo aktualne problematike. Predložene napredne proracunske metode za ocjenjivanje postojecih mostova u vise koraka utemeljene su na probabilistickoj teoriji pouzdanosti, a razmatraju se karakteristicna ispitivanja materijala, ocjene stanja i zalihe nosivosti konstrukcijskog sustava i stvarna prometna opterecenja. Dan je pregled inozemnih normi i napravljena njihova usporedba. Rad sadrži i prijedlog smjernica za izradu hrvatske norme za to podrucje.

BRIDGE ACROSS RIJEKA DUBROVACKA, CROATIA

This paper describes the bridge across Rijeka Dubrovacka in Croatia. The bridge is situated on the western entrance to Dubrovnik, a historical medieval town and well-known tourist destination on the Adriatic coast in Croatia. The existing road passes along the seashore so that increased traffic jeopardizes the environment and harms tourism. The bridge is comprised of a main cable-stayed bridge with prestressed concrete approach bridge and composite superstructure.

EN 1991-2 traffic loads design charts for closed rib orthotropic deck plate based on Pelikan-Esslinger method

Charts for the bending moments in the closed rib orthotropic deck plate are derived, based on the method originally introduced by Pelikan and Esslinger. New charts are done for EN 1991-2 traffic load distribution schemes. The governing Huber plate equation is solved utilizing Fourier series for various bridge deck plate boundary conditions. Bending moments are given as a function of deck plate rigidities and span length between cross beams. Old diagrams according to DIN 1072, the new ones according to EN 1991-2 and FE analyses results are compared. For typical bridge orthotropic deck plates, it can be concluded that the new EN 1991-2 traffic loads produce larger mid-span bending moments when two lane schemes are used, then those of DIN 1072. For support moments, DIN 1072 gives larger values for any number of lanes, especially under span lengths of 5m. The relevant differences are up to 25%.

Analysis and Design of Peljesac Bridge in Croatia

The construction of a new 2.4km long bridge, crossing the sea strait between the Croatian Mainland and the Peljeaac Peninsula to provide the fixed road link between the whole of Croatia, has just begun. The bridge location is in a highly seismic zone with the design ground acceleration of 0.41g and on extremely bad soil. Extensive off-shore site investigations were carried out, including continuous shear wave survey and geotechnical explorations from a specially equipped drill ship, to obtain soil parameters for the design of bridge foundations. A site-specific seismic study was undertaken based on the seismic source zone characterization and attenuation relationships for the south of Croatia. The four lane road bridge consists of two approach bridges and the main cable stayed bridge with continuous steel trapezoidal box superstructure.

Aesthetics of Urban Bridges

Urban bridges very often become benchmarks of the city or metropolis, speciaIly if they presenil aesthetical achievement. This fact has to be accepted during the design process. Therefore the shapf or details of some urban bridge very often try to present some part of cities history, som_ technologies that characterize some city era or are simply dedicated to one time period of the eh) development. The paper shows examples of old bridges constructed centuries ago in the old stone I city of Dubrovnik, one of the best preserved centers of Mediterranean mediaeval architecture. In the vicinity of old bridges, a new cable-stayed urban bridge has been completed in the 2002, with the main span of 303 meters. During the phases of conceptual, preliminary and final design speeial attention has been payed to interaction between historical background and new technologies and materials that had to be applied on a new structure.