Potresni odziv betonskih mostov s pomanjkljivimi konstrukcijskimi detajli

doktorska disertacija

Zlatko Vidrih (Author), Tatjana Isaković (Mentor), Matjaž Mikoš (Thesis defence commission member), Matej Fischinger (Thesis defence commission member), Vojko Kilar (Thesis defence commission member), Mehmed Čaušević (Thesis defence commission member), Matjaž Dolšek (Co-mentor)

Abstract

Keywords

gradbeništvo;disertacije;armirano betonski mostovi;potresna analiza;potresno tveganje;neustrezni konstrukcijski detaili;škatlasti stebri;I stebri;eksperimentalna analiza;modeliranje nelinearnega odziva;

Data

Language:	Slovenian
Year of publishing:	2012
Source:	Ljubljana
Typology:	2.08 - Doctoral Dissertation
Organization:	UL FGG - Faculty of Civil and Geodetic Engineering
Publisher:	[Z. Vidrih]
UDC:	624.21:550.34(043.3)
COBISS:	5775457
Views:	2011
Downloads:	570
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Seismic response of concrete bridges with deficient structural details
Secondary abstract:	In the Ph.D. thesis, the seismic vulnerability and seismic collapse risk of reinforced concrete bridges, with piers with structural details, that are nowadays considered inadequate for seismic prone regions, and were typically used in Slovenia and Europe, were studied. A world wide literature survey concerning response of reinforced concrete bridges in recent earthquakes, typical structural deficiencies in such bridges, experimental studies on hollow box piers, analytical models and methods for seismic performance assessment, and methods for retrofit of such bridges was performed. Among most common structural deficiency found in considered bridge piers is insufficient quantity of transverse reinforcement, which correspondingly means (too) low shear loading capacity, (too) weak concrete core confinement and possibility of longitudinal reinforcement buckling. Analytical studies were supported by experimental studies, which were performed in collaboration with the Slovenian National Building and Civil engineering Institute. In experimental studies, the response of scaled models of the actual prototype piers with hollow box section and of typical cross sections "I" shaped sections, was considered. In the case of as built hollow box specimens their inadequate shear strength was recognized as main deficiency. Therefore the methods for shear strengthening using concrete and FRP jacketing were considered and experimentally tested. In the case of typical I shaped pier its inadequate ductility had been recognised as main deficiency, therefore effort had been made to improve it using FRP jackets. Nowadays the use of FRP jacketing in order to improve the response of bridge piers, is gaining considerable attention in the world, but due to various concerns, it is not yet widely represented in Slovenian practice. Therefore both advantages and disadvantages of using FRP for the purposes of seismic strengthening of RC bridge piers were identified. In the case of as-built hollow box section columns the experimental studies have shown that, despite inadequate structural details, which appear in these columns, quite ductile behaviour can be expected columns (ductility up to 4). The reason for this was favourable box shape, which provides a large compression zone and low compression stress levels. In the case of the I section piers this cannot be said, as the ductility of as built specimen was only about 2. As the current European structural standards in the field of seismic assessment and seismic retrofit are primarily intended for the assessment of buildings, the usefulness of the methods proposed by them were applied to existing bridge structures. The seismic risk of considered structures was determined using the generally accepted PEER methodology taking both the aleatory and epistemic uncertainties into account. It turned out that the bridges with inadequate structural details may be exposed to much greater risk than comparable bridges with the appropriate de
Secondary keywords:	doctoral thesis;reinforced concrete bridges;seismic analysis;seismic risk;inadequate structural details;hollow box piers;I shaped piers;experimental analysis;nonlinear response modelling;Mostovi;Disertacije;Potresno inženirstvo;
URN:	URN:NBN:SI
File type:	application/pdf
Type (COBISS):	Dissertation
Thesis comment:	Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages:	XXXIX, 333 str., [38] str. pril.
Type (ePrints):	thesis
Title (ePrints):	Seismic response of concrete bridges with deficient structural details
Keywords (ePrints):	armirano betonski mostovi;potresna analiza;potresno tveganje;neustrezni konstrukcijski detajli;škatlasti stebri;I stebri;eksperimentalna analiza;modeliranje nelinearnega odziva
Keywords (ePrints, secondary language):	reinforced concrete bridges;seismic analysis;seismic risk;inadequate structural details;hollow box piers;I shaped piers;experimental analysis;nonlinear response modelling
Abstract (ePrints):	V doktorski disertaciji smo študirali potresni odziv armiranobetonskih viaduktov s stebri, ki vsebujejo, z današnjega stališča gledano, neustrezne konstrukcijske detajle in možnosti za utrditev takšnih stebrov z namenom izboljšanja potresnega odziva. Opravili smo pregled literature s področja pomanjkljivosti in potresnega odziva starejših viaduktov, eksperimentalnega odziva stebrov s škatlastim prerezom, numeričnih modelov in metod primernih za analize ter metod za izboljšanje potresnega odziva takšnih viaduktov. Analitične študije smo podprli tudi z eksperimentalnimi študijami v sodelovanju z Zavodom za gradbeništvo Slovenije, s katerimi smo analizirali odziv modelov dejanskih starejših tipičnih stebrov s škatlastimi prerezi, in novejših z I prerezi. Preliminarne analitične raziskave so namreč pokazale, da so slednji zaradi neugodne oblike precej neprimerni za seizmično ogrožena področja. Tipična konstrukcijska pomanjkljivost AB stebrov je neustrezno izvedena in premajhna količina prečne armature, kar obenem pomeni (pre) nizko strižno nosilnost, (pre) majhno objetje jedra prereza in nevarnost uklona vzdolžne armature. Zato je bila v nalogi velika pozornost posvečena tudi ukrepom za izboljšanje odziva stebrov z neustreznimi konstrukcijskimi detajli s pomočjo različnih metod potresnih utrditev. V zadnjem času je v svetu velika pozornost namenjena predvsem utrditvam s sodobnimi kompozitnimi (FRP) plašči, ki pa zaradi različnih pomislekov, vsaj v slovenski praksi še niso zelo zastopani. V ta namen so identificirane tako prednosti kot slabosti uporabe FRP za namene potresnih utrditev AB mostnih stebrov. V primeru neutrjenih škatlastih stebrov so eksperimentalne raziskave pokazale, da lahko, kljub kopici neustreznih detajlov, ki se pojavljajo v takšnih stebrih pričakujemo delno duktilno obnašanje stebrov (duktilnost do 4), medtem ko v primeru I stebrov tega ne moremo reči, saj so dosežene duktilnosti (brez varnostnih faktorjev) le okrog 2. Ker so standardi s področja ocene potresnega odziva in potresnih utrditev konstrukcij (angl. seismic assessment and retrofit) namenjeni predvsem utrditvam stavb, smo preverili uporabnost metod, ki jih ti predlagajo, za analizo potresnega odziva premostitvenih konstrukcij. Za oceno potresnega tveganja obravnavanih konstrukcij smo uporabili splošno uveljavljeno PEER metodologijo z upoštevanjem tako aleatornih kot epistemičnih nezanesljivosti. Izkazalo se je, da so mostovi z neustreznimi konstrukcijskimi detajli lahko izpostavljeni precej večjemu tveganju kot primerljivi mostovi z ustreznimi detajli.
Abstract (ePrints, secondary language):	In the Ph.D. thesis, the seismic vulnerability and seismic collapse risk of reinforced concrete bridges, with piers with structural details, that are nowadays considered inadequate for seismic prone regions, and were typically used in Slovenia and Europe, were studied. A world wide literature survey concerning response of reinforced concrete bridges in recent earthquakes, typical structural deficiencies in such bridges, experimental studies on hollow box piers, analytical models and methods for seismic performance assessment, and methods for retrofit of such bridges was performed. Among most common structural deficiency found in considered bridge piers is insufficient quantity of transverse reinforcement, which correspondingly means (too) low shear loading capacity, (too) weak concrete core confinement and possibility of longitudinal reinforcement buckling. Analytical studies were supported by experimental studies, which were performed in collaboration with the Slovenian National Building and Civil engineering Institute. In experimental studies, the response of scaled models of the actual prototype piers with hollow box section and of typical cross sections "I" shaped sections, was considered. In the case of as built hollow box specimens their inadequate shear strength was recognized as main deficiency. Therefore the methods for shear strengthening using concrete and FRP jacketing were considered and experimentally tested. In the case of typical I shaped pier its inadequate ductility had been recognised as main deficiency, therefore effort had been made to improve it using FRP jackets. Nowadays the use of FRP jacketing in order to improve the response of bridge piers, is gaining considerable attention in the world, but due to various concerns, it is not yet widely represented in Slovenian practice. Therefore both advantages and disadvantages of using FRP for the purposes of seismic strengthening of RC bridge piers were identified. In the case of as-built hollow box section columns the experimental studies have shown that, despite inadequate structural details, which appear in these columns, quite ductile behaviour can be expected columns (ductility up to 4). The reason for this was favourable box shape, which provides a large compression zone and low compression stress levels. In the case of the I section piers this cannot be said, as the ductility of as built specimen was only about 2. As the current European structural standards in the field of seismic assessment and seismic retrofit are primarily intended for the assessment of buildings, the usefulness of the methods proposed by them were applied to existing bridge structures. The seismic risk of considered structures was determined using the generally accepted PEER methodology taking both the aleatory and epistemic uncertainties into account. It turned out that the bridges with inadequate structural details may be exposed to much greater risk than comparable bridges with the appropriate de
Keywords (ePrints, secondary language):	reinforced concrete bridges;seismic analysis;seismic risk;inadequate structural details;hollow box piers;I shaped piers;experimental analysis;nonlinear response modelling
ID:	8312374