Zlatko Savor

University of Zagreb, Faculty of Civil Engineering, Department of Structures, Department Member

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Papers by Zlatko Savor

Pokusno opterećenje novog Masleničkog mosta

Četvrti opći sabor HDGK, Jun 7, 2002

Reconstruction of the Pag Bridge

PROCEEDINGS OF THE 10TH INTERNATIONAL CONFERENCE AND EXHIBITION - STRUCTURAL FAULTS AND REPAIR CONFERENCE 2003, HELD LONDON, JULY 2003 - CD ROM, 2003

The Pag bridge was thoroughly reconstructed because of heavy damages caused by reinforcement corr... more The Pag bridge was thoroughly reconstructed because of heavy damages caused by reinforcement corrosion. The design of new steel superstructure is presented. The repair of piers is briefly described. Effects of the superstructure replacement on the arch behaviour are discussed. The numerical analysis showed high sensitivity of the relatively elastic arch to the change of dead weight distribution. For the covering abstract see ITRD E122906.

Impact of Eurocode Load Model 3 on the design of highway and expressway bridges

Road and rail infrastructure, May 11, 2022

According to Eurocode HRN EN 1991-2 and Croatian National Annex HRN EN 1991-2/NA highway and expr... more According to Eurocode HRN EN 1991-2 and Croatian National Annex HRN EN 1991-2/NA highway and expressway bridges need to be designed for Load Model 1 (heavy vehicles) and Load Model 3 (special vehicles) traffic loads. Classes of special vehicles are defined in Annex A of HRN EN 1991-2, while the Croatian National Annex requires the use of 15 axle special vehicle with total weight of 3000 kN and axle loads of 200 kN. The simultaneity of LM1 and LM2 is also covered by the standard, depending on the travel speed of the special vehicles. Design practice has shown that these design requirements have notable impact on bridges in the 30 to 100 m span range. In this paper, the results of a parametric study on a group of continuous girder bridges with different spans and carriageway widths are presented, to determine the exact difference in resulting hogging and sagging moments and shear forces between LM1 and LM3 Load Models. Thus, the governing Load Model and its effect on the design for the relevant range of bridges is determined. A recommendation is made as to when each Load Model should be used in design.

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Analysis on durability of reinforced concrete bridges in maritime environment

The paper provides a review of durability issues of the Adriatic large concrete arch bridges buil... more The paper provides a review of durability issues of the Adriatic large concrete arch bridges built in two periods: in the 1960’s and 1970’s and at the last turn of the century. Inadequate attention to durability issues in combination with very aggressive maritime environment has led to rapid deterioration of the structures caused by corrosion of reinforcement steel in concrete. In order to develop consistent maintenance policy that would provide efficient and effective management of bridges in maritime environment, it is necessary to determine remaining service life of the structures. In this purpose the coupled 3D chemo- hygro-thermo mechanical model is developed and implemented into FE code. The applications of the model are illustrated on three numerical examples. The numerical results are in good agreement with the available experimental data leading to the conclusion that the model is able to realistically predict service life of reinforced concrete structures exposed to chlorides and mechanical damage results. In service performance of the Adriatic large concrete arch bridges shown and numerical analysis confirmed the following: (i) cracks in concrete cover, which are the consequences of mistakes in conceptual design as well as errors and negligence on site, significantly reduces depassivation time of reinforcement bar ; (ii) corrosion rate is much higher in poor than in good quality concrete ; (iii) the maximal numerical results of corrosion rate, achieved at critical water saturation, are within the limits for concrete in splash zone, as one of the most critical environment for corrosion of steel in concrete, (iv) corrosion induced cracks significantly reduce pull-out capacity of reinforcement.

Bridge across Rijeka Dubrovačka

Prikazan je projekt mosta preko Rijeke Dubrovacke, koji je inacica osnovnog projekta mosta iz 198... more Prikazan je projekt mosta preko Rijeke Dubrovacke, koji je inacica osnovnog projekta mosta iz 1989. godine, uz pridržavanje svih zadanih parametara iz osnovnog projekta. Most cine 147.4 metra dugi prednapeti prilazni zapadni vijadukt i glavni nesimetricni most sa kosim zategama s spregnutim rasponskim sklopom duljine 334 m. U clanku se navode temeljne znacajke osnovnog projekta i inacice i ukazuje na razlike u konstruktivnom oblikovanju.

Dubrovnik bridge - design, construction and service performance

The only cable stayed bridge in Croatia, the Dubrovnik bridge, was opened for traffic in the year... more The only cable stayed bridge in Croatia, the Dubrovnik bridge, was opened for traffic in the year 2002. The cable stayed main bridge with composite superstructure is jointed in span to the prestressed concrete approach bridge by a hinge type hinge connection. The main and detailed designs were carried out by the team from the Structural Department of Civil Engineering Faculty in Zagreb, based on preliminary design by Prof. Schambeck and Sporschill [1] . Essentials of the Dubrovnik bridge design and construction are presented in the paper. The bridge has experienced vibrations of stay cables 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 rain-wind induced stay cable vibrations are highlighted. Only after extremely violent movements of stay cables and the superstructure under heavy damp snow storm occured, resulting in substantial damage, was it decided to apply vibration mitigation measures. Adjustable cable dampers, based on MR technology were installed on the bridge to raise low structural damping of mostly affected stay cables. Theoretical computations suggest that the stay cable vibrations shall be strongly reduced. Accelerometers and displacement transducers shall be placed on some stay cables to continuously monitor their motion.

Maintenance and Repair of Large Concrete Arch Bridges

Four large concrete arch bridges were built on the Croatian Adriatic coast during the sixties and... more Four large concrete arch bridges were built on the Croatian Adriatic coast during the sixties and the seventies, spanning 193 m to 390 m. All these arches were erected utilising the free cantilevering method. All bridges have the box type arch cross-section, consisting of three cells, slender piers, and superstructure comprising precast prestressed concrete girders. These all bridges exhibit some common characteristics ; minimum dimensions of structural elements and a thin concrete cover, which influence their durability. Results of inspections and testing confirmed degradation of structural parts, primarily due to inadequate conceptual design, errors on site and exposure to aggressive maritime environment. Only minor repairs had been performed on the Sibenik Bridge. The Pag bridge was completely renewed: the arch was repaired in 1991., and the superstructure was replaced in 1999. Repairs of the piers and the superstructure are in progress on the Krk Bridge. Various solutions for the arch protection have been investigated, but none of them adopted yet. The Maslenica bridge, completed in 1997., is a concrete arch of 200 meters span. It was designed taking into the account the severity of the marine environment, and the experience from inspections of other arch bridges. The paper presents an overview of maintenance and repair of the bridges in the marine environment. Design recommendations for bridges over sea straits derived from experience and applied to the Maslenica arch bridge, are given.

Design and construction of Mirna viaduct

The Mirna viaduct crosses the Mirna River valley on Nova Vas – Visnjan section of the Istrian “ Y... more The Mirna viaduct crosses the Mirna River valley on Nova Vas – Visnjan section of the Istrian “ Y” west leg state road. The construction of the viaduct started in 2002 and it was opened for traffic in June 2005. The overall viaduct length is 1, 378.03 m, with spans L=51.07+15x66.491+70.096+2x50.069+63.087+42.558+30, 542=1354.86 m. The ground plan alignment of the viaduct is in constant curvature of 4, 005.5 m. The vertical grade line alignment is in uniform concave curvature of 17, 500.0 m, following the terrain profile to limit the height of viaduct columns. The overall width of the viaduct deck without cornices is 10.10 m. The relatively slender continuous superstructure comprises two main steel 2, 750.0 mm deep plate girders spaced at 5, 500.0 mm, cross beams in frame action and a concrete 25.0 cm deep deck plate in composite action with main girders. A relatively unusual structural bearing layout was adopted, with longitudinally fixed bearings on 13 middle piers, made possible by the low horizontal stiffness of friction steel pile foundations in adverse soil conditions. The superstructure is longitudinally restrained at both abutments by viscous dampers. All viaduct piers are very slender of H shaped cross section, comprising a 30.0 cm web and two 35.0 cm flanges extending in the direction of the bridge axis, with varying height 13.45÷40.026 m. Shallow spread foundations are utilized on the solid rock of Mirna valley slopes. All piers in the valley are founded on long driven steel friction piles. Piers were constructed in climbing formwork in 5.0 m long segments with high precision because of their extreme slenderness. The erection of the superstructure was executed by longitudinal launching of steel grillages from both abutments. Concreting of the deck plate was executed on temporary formwork, in strictly prescribed order. A short review of design and construction of the Mirna viaduct is presented in the paper.

Krka River Bridge Near Skradin

The new Adriatic highway crosses the canyon of the Krka river in protected environment, in proxim... more The new Adriatic highway crosses the canyon of the Krka river in protected environment, in proximity of the national park. The location of the bridge is in the Mediteranean area of high seismic risk. Several preliminary designs have been reviewed for this crossing, and finally a concrete arch of 204 m span had been chosen for construction. The arch cross-section is of the double cell box type. The superstructure is composite, comprising steel girders and reinforced precast concrete deck-plate. The bridge is currently under construction, to be completed by the end of 2004. The arch, which was completed in April 2004, was built by free cantilever procedure, using cable-stays and steel auxiliary pylons. The steel superstructure grillage is erected incrementally in three phases, the first two from both abutments to the main piers to facilitate transport to auxiliary steel pylons and the third one launching the steel superstructure above the arch.

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Design and construction of Krka bridge near Skradin

A new concrete arch bridge with 204.0 m span was constructed across the Krka River canyon on the ... more A new concrete arch bridge with 204.0 m span was constructed across the Krka River canyon on the section Skradin-Sibenik of the Adriatic highway. The bridge site lies in an environmentally protected area very close to the Krka national park. The superstructure is continuous with spans L=3x32.0+3x28.0+3x32.0+28.0+24.0=360.0 m comprising two main steel box-type beams spaced at 7.6 m, strong steel cross beams and a concrete deck plate in composite action with both main and cross beams. The application of the composite superstructure, made possible significant reduction of the dead weight and enhanced the bridge appearance in comparison to other Croatian concrete arch bridges. Because of the importance of the Krka River bridge and aggressive environment monitoring system was installed for measurements of deformations, local temperature values, movements in service at critical points and corrosion rate. The construction of the bridge across the Krka River canyon commenced in the year 2003 and was successfully completed in two years in 2005. The whole arch cross section was constructed by free cantilevering, on traveling formwork carriages, in segments 5.25 meters long, starting symmetrically from arch abutments. Piers at the arch abutments had to be extended by auxiliary steel staying pylons to facilitate successive cantilevering. The arch was supported during construction by stays equilibrated by anchor stays, connected to rock anchors. The steel superstructure grillage was erected by longitudinal launching in three phases. The concrete deck is formed from full depth precast slabs interconnected by on site concreting of longitudinal and transversal joints above shear connectors.

New Croatian Bridges

A short overview on larger Croatian bridges is presented. Some of them have been recently finishe... more A short overview on larger Croatian bridges is presented. Some of them have been recently finished, and some are currently under construction. All bridges to be presented are designed at the Structural Department of Civil Engineering Faculty in Zagreb, Croatia. In the conclusion of the article, some aspects of conceptual design problems shalI be highlighted. The Maslenica Highway Bridge, completed in 1997., is a concrete arch of 200 meters span. The arch cross ii section is box type, double ceH with depth to width ratio of 4.0/9.0 metres. The arch was constructed by free cantilevering on travelling formwork carriages in 5.26 m long segments. The superstructure comprises eight simple-span precast prestressed girders made continuous over intermediate supports and interconnected by concrete deck slab cast in situ. The bridge was designed taking into the account the severity of the marine environment, and the experience from inspections of other arch bridges. Bridge similar to Maslenica is to be built on the new Adriatic highway crossing the canyon of the Krka river. Several preliminary designs have been reviewed for this crossing, and finally a concrete arch of 210 m span chosen for construction. The Bridge across the Rijeka dubrovacka is currently under construction. It comprises two technologically completely different superstructures, prestressed concrete box of the approach bridge and main composite Cable stayed bridge. Box girder, 60 m long and constructed by free cantilevering is connected to a Cable stayed bridge 244 m long, making a clear span of 304 m. The bridge is to be completed by the end of 200 1. The bridge over the Drava river at BeliAE#263 ; e consists of two - span continuous main composite bridge and prestressed concrete approach viaducts. The superstructure of the composite bridge comprises two steel plate girders with variable height and reinforced concrete deck plate. The constraints of river traffic dictated the layout of main bridge with spans of 95.5 m and one pier in the river bed. The bridge over the Sava river at Martinska Ves is a 145 m span suspension pedestrian bridge, 4 m wide. Bridge layout was chosen according to the restraints of river traffic. Curently under construction, it shalI be finished by the spring 2002. The Dobra Vrbovsko bridge crosses 65 m deep valley. The prestressed concrete box type superstructure is continuous over 5 spans, with maximum length of 50 m. The incrementallaunching construction method of the superstructure is selected. For the first time in Croatia external prestressing with tendons inside the box girder was adopted for additionalload and live loads. Construction works started in the October 200 1. The Kamacnik bridge crosses the river valley, 60 m deep, in protected environment. The prestressed concrete box type superstructure has three spans, 71 + 127 + 24 m. Cantilever construction procedure is to be executed, utilizing counterweight on the end of the shortest span and one auxilliary piero

Dugotrajne deformacije konzolno građenih mostova

Građevinar : časopis Hrvatskog saveza građevinskih inženjera, 2004

Gredni mostovi građeni konzolnim postupkom

Nove tehnologije u hrvatskom graditeljstvu, 2003

Betonski gredni mostovi

Zlatni sabor HDGK 1953.-2003., 2003

Parametric Analysis of Steel Arch Bbridgers

International Conference on Bridge Engineering - Challenges in the 21th Century : Proceedings, 2006

Mostovi na novim hrvatskim autocestama

Prikaz hrvatskih postignuća, 2002

Suvremeni pristup proračunu konstrukcija

Prvi hrvatski dani betona, 2005

Seismic Designs of Some Recent Bridges Created by the Structural Department of Zagreb Faculty of Civil Engineering

1st Croatian Conference on Earthquake Engineering, 2021

Over the last 20 years, beside their primary educational activities, members of the Bridge Chair ... more Over the last 20 years, beside their primary educational activities, members of the Bridge Chair of the Zagreb Faculty of Civil Engineering Structural Department also worked professionally on main and execution designs of many bridges. Most of them are mid-span to large span bridges, requiring detailed seismic design, especially since their locations are predominantly in highly seismic active regions. These bridges were designed during the transition period from old seismic standards, to ENV pre-standards, and finally to EC8 standards. The evolution of these codes had a great impact on the design. New demands in terms of seismic behaviour influenced all aspects of design, from conceptual design (structural system and material options), sizing of elements, foundation type, bearing and damper layouts, special equipment selection, erection details, to maintenance requirements. An overview of seismic design requirements, solutions, and peculiarities for each of these bridges, which were recently constructed or are currently under construction, is presented in the paper. Since the design of the cable stayed bridge Franjo Tuđman in Dubrovnik, where fluid viscous dampers were first employed in Croatia, to the recent bridge designs, various approaches were utilized to mitigate and take over the seismic actions. Adequate solutions were found either by structural detailing and/or by installation of seismic isolators, depending on bridge structural systems, utilized materials, but also on the characteristics of foundation soil.

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Long-term deformations on cantilever girder bridges

jedan od sredisnjih problema konzolno građenih grednih armiranobetonskih mostova jesu dugotrajne ... more jedan od sredisnjih problema konzolno građenih grednih armiranobetonskih mostova jesu dugotrajne deformacije. Cinjenica je da je na vecini tako sagrađenih mostova kroz proteklih pola stoljeca uocena velika razlika između proracunatih i kasnije izmjerenih progiba. Jos nije potpuno utvrđeno sto utjece na te progibe. Prikazana je analiza dostupnih podataka s niza mostova izvedenih diljem svijeta i moguci razlozi pojava velikih deformacija i njihovih neslaganja s projektiranim.

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Contemporary access to analysis of stuctures

Suvremeni pristup proracunu konostrukcija temelji se na pretpostavci da ne postoji potpuna sigurn... more Suvremeni pristup proracunu konostrukcija temelji se na pretpostavci da ne postoji potpuna sigurna konstrucija pa koristi probabilisticko poimanje sigurnosti. Kako u sadasnjoj fazi nedostaju opsežni statisticki podaci koristi se semiprobabilisticki koncept sigurnosti u kojem se samo neke dominantne velicine statisticki određuju i determiniraju, a dalje se postupa kao u deterministickom konceptu.