Jure Radić

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.

Life-cycle Performance Model Based on Homogeneous Markov Processes

All civil engineering structures are deteriorating in time, at a different rate. The current and future states of a structure are associated with various degrees of uncertainty, and, therefore, a probabilistic approach is appropriate in order to predict future needs for maintenance and repair. Some existing models use discrete-time Markov processes called Markov chains. In this paper, homogeneous Markov processes (HMPs) with a finite set of condition states and a continuous parameter (time) are used. The aim is to make a probabilistic forecast of the condition of the structure, using time as a continuous parameter, so that probabilities of condition states can be calculated at each moment. The model is applied to the calculation of probability of possible future deterioration of the piers of Krk bridge (Croatia) that have already been repaired.

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.

Maintaining safety and serviceability of concrete bridges in Croatia

This paper discusses the management, maintenance and repair of Croatian bridges. Unfortunately, activities related to bridge maintenance are not carried out regularly, but on an ‘as-needed’ basis with inspection and testing undertaken only when structural damage becomes self-evident. Poor in-service performance and condition of existing bridges in Croatia led to the conclusion that the currently employed approach to solving bridge maintenance issues is not satisfactory, and should be improved. The framework for more efficient bridge management in terms of the bridge management system named HRMOS exists. Unfortunately, the introduction of HRMOS did not ensure that the activities related to bridge maintenance are carried out regularly nor according to the prescribed procedures. To illustrate the grave consequences of neglecting bridge maintenance activities, several case studies are discussed, including world-renowned structures such as the Krk bridges. These clearly show that if we choose to act only when ...

Seizmičko ocjenjivanje postojećih armiranobetonskih lučnih mostova

U ovome je radu prikazana nova metoda seizmickog ocjenjivanja lucnih mostova. Linearni proracun metodom spektralne analize i nelinearne staticke metode postupnog guranja kombiniraju se u ovoj proceduri kroz razine ocjenjivanja i pripadne provjere. Predlažu se smjernice za prikupljanje podataka o lucnim mostovima s ciljem ostvarivanja tražene razine poznavanja konstrukcije. Pritom su kriteriji za seizmicku ocjenu, primjerice zahtijevano sudjelovanje djelotvorne modalne mase, prikladna raspodjela krutosti nadlucnih stupova i utvrđivanje poredbene tocke za formiranje krivulja kapaciteta, ovom metodom poboljsani i prilagođeni lucnim mostovima.

Assessment of bridges in aggressive maritime environment

Research on development of assessment procedure for existing bridges exposed to wind load is presented in this paper. Both linear and the nonlinear methods are used and probabilistic model of wind load is developed. The results were evaluated following the demands defined by current European design codes and specific location conditions. This procedure is validated by its application to major Adriatic arch bridges with spans ranging from 200 m to almost 400 m as a part of an extensive project to develop their appropriate maintenance strategy.

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.

New Zagreb Airport terminal – form giving structure

New Zagreb airport terminal is currently being built following the winning design from an international competition called upon by Zagreb City in 2008. After some pause, the project was rebooted in 2012, when Croatian government signed a concessionary agreement with French company Bouygues for the erection of the terminal according to the winning design, granted some minor changes. The awarded design by two architects Branko Kincl and Velimir Neidhardt, and one structural civil engineer Jure Radic, comprises an integral multidimensional approach between the structure, form, urbanism, ecology, functionality and aesthetics. The identity of the building is achieved with an elegant double curvature fluid form of its roof structure which comprises a steel space truss with spans of 43 m. The inner structure of the terminal is all concrete and monolithic, comprising mainly prestressed floor slabs (spanning 7.2 m and 14.4 m) and shear walls.

Holistic Approach to Design of New Bridges Across Sava River in Zagreb

Zagreb, Croatian capital, is situated on both Sava river banks. However, currently there are only seven bridges across the river in the inner city limits. To solve the problem of the inadequate capacity of the Sava River crossing in Zagreb, two new bridges are planned in the near future as part of the solution for sustainable development of the Sava River banks area in Zagreb. Differences in planning and design of bridges in 20th and 21st century will be analyzed highlighting new applied, holistic approach to design Jarun and Bundek Bridge.

Design and assessment of concrete surface protection systems

Properly designed reinforced concrete structures can be very durable in most environments. However, in some cases, surface protection of concrete must be executed to achieve the required service life of a new structure (preventive measure), or to extend the service life of a repaired concrete structure. Surface protections are products and systems that contribute to the durability of concrete and reinforced concrete structures. Rapid degradation and reduction of service life generally occurs on reinforced concrete structures in a maritime environment, although they are designed according to the regulations in force at present and to the European standards 206-1 and 1992-1-1.The most common cause of degradation of reinforced concrete structures is corrosion of the reinforcement. In maritime environments chlorides are always a relevant environmental action. Durability of reinforced concrete structures is therefore determined by the ability of aggressive agents from the surrounding environment to penetrate i...