Spremembe predpisov za projektiranje mostov in njihov vpliv na lastnosti tipičnega armiranobetonskega nadvoza : magistrsko delo

Švraka, Ratko (author), Isaković, Tatjana (mentor), Kreslin, Maja (comentor)

Staranje slovenskih premostitvenih objektov vse pogosteje zahteva analizo varnosti kritičnih objektov. Eden izmed glavnih vhodnih podatkov pri analizi varnosti premostitvenega objekta je nosilnost armiranobetonskega prereza, na katero ključno vpliva količina vgrajene armature. V sklopu naloge je primerjanih šest gradbenih standardov, ki so bili na področju Slovenije v uporabi od druge svetovne vojne do danes. Obravnavani standardi za določanje prometne obremenitve mostov so jugoslovanski PTP 5, nemški DIN 1072 in slovenski SIST EN 1991-2. Merodajna obtežba za dimenzioniranje prekladne konstrukcije je praviloma prometna obtežba, kar pa ne velja za podporno konstrukcijo, kjer je prevladujoči vpliv potresna obtežba. Obravnavana standarda za določitev potresne obtežbe sta jugoslovanska predpisa iz leta 1964 in 1981, ter slovenski standard SIST EN 1998. V prvem delu naloge so predstavljeni obravnavani standardi in postopek določanja obtežbe. Kot referenčni objekt je bil izbran fiktiven armiranobetonski nadvoz preko štirih polj, ki je na slovenskih avtocestah zelo razširjen. Nadalje je prikazan numerični model mostu v programu Midas Civil. V drugem delu je določena obtežba posameznih standardov za izbrani objekt in z numerično analizo izračunan razpored notranjih statičnih količin. Za tri karakteristične prereze je določena merodajna kombinacija notranjih statičnih količin za dimenzioniranje. Slednje je potekalo v dveh sklopih. Za standarde, starejše od Evrokod standardov je bila v uporabi metoda dopustnih napetosti, ki jo je v začetku devetdesetih let prejšnjega stoletja zamenjala danes uveljavljena metoda mejnih stanj. Po opisu obeh metod je prikazan račun potrebne armature za izbrane prereze. V zadnjem delu je prikazana analiza pridobljenih rezultatov, kjer je za izbrani objekt izvedena primerjava vpliva standarda in primerjava metode za določitev nosilnosti na končno količino armature.

• Language: Slovenian
• Keywords: primerjava prometnih standardov, primerjava potresnih standardov, metoda dopustnih napetosti, metoda mejnih stanj, PTP 5, DIN 1072, Evrokod
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publisher: [R. Švraka]
• Year: 2020
• PID: 20.500.12556/RUL-114871
• UDC: 624.042.7:624.2/.8(497.4)(043.3)
• COBISS.SI-ID: 22473987
• Publication date in RUL: 21.03.2020

Secondary language

• Language: English
• Title: Changes of regulations for bridge design and their impact on the characteristics of a typical reinforced concrete overpass : master thesis

Abstract

Due to aging of the Slovenian bridging structures safety analyses of critical structures are increasingly required for the critical structures. One of the major load-bearing factors for reinforced concrete cross-section and consequently one of the key factors for conducting safety analysis is the amount of built –in reinforcement. The thesis compares six building standards that have been in use in Slovenia since World War II until today. The standards under consideration for determining the traffic load of bridges are Yugoslav PTP 5, German DIN 1072 and Slovenian SIST EN 1991-2. The relevant load for dimensioning the superstructure is generally the traffic load, which is not the case for supporting structure, where earthquake load is the dominant one. The considered regulations and standards for determining earthquake load are the Yugoslav regulations from 1964 and 1981, and the Slovenian standard SIST EN 1998. The first part of the thesis presents the individual standards and procedure for determining the load. A fictitious reinforced concrete overpass over four fields has been selected as the reference object, which is widespread on the Slovenian motorways. Further, a numerical model of the bridge that was constructed in Midas Civil software is presented. The second part presents the loads of individual standards numerical analysis results in the form of internal forces and moments. For three characteristic sections the relevant combination of internal forces and moments for dimensioning, which took place in two sets, is determined. For the standards prior to the Eurocode standards, the tolerable stress method was used, which was replaced by the widespread limit state method in the early 1990s. After the description of both methods, the necessary reinforcement for the selected cross sections is calculated. In the last part, analysis of the obtained results is presented, where comparison of the influence of the standard and the method for determining the load on the final value of the reinforcement is made for the selected overpass.

• Keywords: comparison of traffic standards, comparison of earthquake standards, tolerable stress method, limit state method, PTP 5, DIN1072, Eurocode