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.Many bridges in the world have been built a long time ago and, because of social and economic needs for their continued use, it is necessary to assess their reliability. An overview of recent studies of these now highly topical issues is presented in the paper. Proposed advanced multi-level methods for assessment of existing bridges are based on the probabilistic theory of reliability, and involve typical material testing, assessment of condition and redundancy of structural systems, and study of actual traffic load. A review of foreign codes with their comparison is presented

Seismic risk for Croatia: overview of research activities and present assessments with guidelines for the future

Iz pozicije glavnog izvršitelja za procjene rizika od potresa za Hrvatsku, napravljen je pregled brojnih i metodološki različitih procjena rizika, uključujući nepovezane pojedinačne inicijative. Cilj rada je pozicionirati i osvrnuti se na doprinose svake od procjena, ali i upozoriti na manjkavosti odnosno ograničenja. Opisana je i uobičajena metodologija analizirajući svaki od faktora seizmičkog rizika, dajući pregled sadašnjeg stanja istraživanja u Hrvatskoj i u svijetu te nudeći smjernice za daljnje strateško djelovanje jer svi postojeći rezultati ističu potres kao neprihvatljiv rizik za Hrvatsku.An overview of numerous methodologically different risk assessments, including sporadic individual initiatives, is presented from the perspective of a leading expert for earthquake risk assessments for Croatia. The aim of the paper is to evaluate and discuss contributions of each of the assessments, but also to caution about their deficiencies i.e. limitations. A common methodology for estimating seismic risk is described by analysing each of its factors, by providing an overview of current research in Croatia and worldwide, and by offering guidelines for further strategic actions, as all existing results reveal that earthquake is an unacceptable risk for Croatia

On the design of walls with openings

U radu se opisuje postupak proračuna zidova s otvorima koji je Veselin Simović uveo početkom sedamdesetih godina prošloga stoljeća. Rješenje je izvedeno u zatvorenom obliku prevođenjem sustava jednadžbi metode sila u linearnu diferencijsku jednadžbu s konstantnim koeficijentima. Spomenuti je postupak proračuna zidova s otvorima uspoređen s „modernijim“ postupkom proračuna metodom pomakâ, provedivim samo primjenom računala. Usporedbe rezultata pokazuju ograničenja primjenjivosti postupka, odnosno, vrste zidova za koje se rezultati mogu smatrati pouzdanima

Post-earthquake damage assessment of buildings – procedure for conducting building inspections

Procjene oštećenja i uporabljivosti građevina u Hrvatskoj, iskočile su u prvi plan nakon potresa u Zagrebu 22. ožujka 2020. S obzirom na manjkavosti pripremne faze, pri čemu nije provedena edukacija stručnjaka prije potresa, nego u hodu, procjene su sadržavale dozu subjektivnosti i interpretacije na temelju znanja, iskustva, ali i intuicije pojedinaca. U radu je detaljno prikazana metodologija koja može pomoći u brzim procjenama te kod detaljnih inženjerskih pregleda koji se moraju napraviti prije obnove. Prikazana metodologija se može iskoristiti u slučaju novoga razornog potresa koji se može dogoditi već sutra.Assessments of building damage and usability were of primary importance after the Zagreb earthquake of 22 March 2020. Due to deficiencies of preparatory phase, where education of experts was not carried out before the earthquake, but later on, the assessments contained certain subjectivity and interpretations, based on knowledge and experience, but also on intuition of individuals. Detailed methodology, which should improve rapid assessments and detailed engineering inspections to be performed before reconstruction, is highlighted in the paper. This methodology may be utilized if another devastating earthquake occurs, which could happen already tomorrow

Zagreb earthquake of 22 March 2020 – preliminary report on seismologic aspects and damage to buildings

U radu su opisane bitne značajke i glavne posljedice potresa magnitude 5,5 koji je u jeku pandemije virusa COVID-19 zadesio Zagreb i okolicu. Premda je potres, seizmološki gledano, bio umjerene magnitude, prouzročio je gubitak jednoga života i veliku materijalnu štetu. Napravljen je pregled stanja prije trešnje te prikaz lokacije, seizmičke aktivnosti i organizacije pregleda zgrada. Grubo su razvrstani podaci o oštećenjima, s težištem na povijesnoj jezgri i četvrtima blizu epicentra. Na kraju su istaknute nužne aktivnosti koje je odavno trebalo provesti, s nadom da će ih ovaj potres potaknuti.Significant characteristics and main consequences of the 5.5 magnitude earthquake that struck Zagreb and its surroundings in the midst of the COVID-19 pandemic are presented in the paper. Although, from the seismologic aspect, the earthquake was of moderate magnitude, it caused the loss of one life and considerable material damage. An overview of the situation before the quake is given, and information about the location, seismic activity, and organisation of building inspection activity, is presented. The data on damage are roughly classified, with the focus on historic core of the city and districts situated close to the epicentre. A strong emphasis is placed on indispensable activities that should have been carried out a long time ago, in the hope that they will be prompted by this earthquake

Influence of spatial variability of ground motion on seismic response of bridges

An approach to seismic analysis of bridges under spatially variable ground motions is presented. The phenomenon of spatial variability of earthquakes, its effects on bridge response, and differences with respect to simultaneous excitation of supports, are explained. The model of such excitation is described in detail, and procedures for generation of spatially variable ground motions are outlined. Numerical analysis methods, efficient for solving this problem, are also presented. The described methodology is applied in the seismic analysis of an arch bridge. The analysis results show that the spatial variability of ground motions has a detrimental effect on most of the analysed bridge response values

Sanacija tradicijskih kamenih stupova olovnim umetkom

Na tradicijskim kamenim stupovima često se mogu uočiti karakteristične pukotine u području spojeva, ali i različite načine sanacija kojima se pokušavalo zaustaviti njihovo kontinuirano širenje. Sustavnim je numeričkim i laboratorijskim analizama na gotovo realnim dimenzijama uzoraka kao temeljni uzrok raspucavanja orkrivena koncentracija naprezanja na kontaktnim plohama. U radu je prikazan dio rezultata laboratorijskih ispitivanja i numeričkih analiza tradicijskoga oblika sanacije s olovnim umetkom postavljenim između dijelova stupa

Damage Evaluation and Seismic Assessment of a Typical Historical Unreinforced Masonry Building in the Zagreb 2020 Earthquake: A Case Study—Part I

The city of Zagreb, the national capital and economic hub of Croatia, is situated in a seismically active region and hosts a significant array of historical buildings, from the medieval to Austro-Hungarian periods. These buildings possess varying but generally high degrees of vulnerability to seismic loading. This was highlighted in the Zagreb earthquake of 22 March 2020, emphasizing the need for seismic retrofitting in order to preserve this architectural heritage. In this paper, the seismic capacity of one such unreinforced masonry building is considered through a number of analysis methods, including response spectrum, pushover, and out-of-plane wall failure analyses. Given the advantages and disadvantages of the individual methods, their applicability and value in a seismic analysis is considered. Ambient vibration measurements before and after the Zagreb 2020 earthquake, used for model calibration, are also presented. Conclusions are drawn from each individual analysis and later compared. In conclusion, no single analysis method considers all relevant failure modes, and a combination of nonlinear static or dynamic analysis and out-of-plane analysis is recommended. Due to the large volume of the material, it is published in two parts, with ground motion record selection, dynamic analysis, and a comparison of the results published in part two