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Browsing Deprem Mühendisliği by Subject "Bridges -- Earthquake effects -- Turkey."
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Item An evaluation of the behaviour of RC bridge piers under vertical and horizontal components of earthquake ground motion(Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2019., 2019.) Abanuz, Cem.; Hancılar, Ufuk.Reinforced concrete (RC) bridges with single piers have been used extensively in Turkish highways. During the past earthquakes in Japan, USA and New Zealand extensive damages occurred in the single piers indicates the inadequacy of seismic design. In the design of the concrete bridge piers, generally horizontal earthquake forces are taken into consideration. An additional P-∆ effect occurs when the horizontal earthquake effect and the vertical earthquake effect act together on the bridge piers with a large beam cantilever width. The effect of additional P-∆ effect under the effect of vertical earthquake may increase the bending moment and shear forces values in the columns and the piers supporting the bridge may experience damage. Another circumstance encountered in large-scale projects is the use of filler material as a dump / storage area under bridge piers. This causes a certain part of the bridge pier heights to remain under the soil filling material and shortens the free pier height. For a single column pier of a conventional bridge maximum moment and shear values occur at the bottom of the column under seismic forces. This region where the maximum stress occurs is designed to be the plastic hinge region of the column. Maximum shear and longitudinal reinforcement used in the plastic hinge region to provide the conditions is stated in the regulations. When the part of the column is buried under the soil, maximum moment and shear force values of the bridge columns may not occur at the bottom of the column but at the upper end of the buried height. Therefore, the critical section of the column will be above the bottom of the column which was not considered in the seismic design. The amount of longitudinal and shear reinforcement may also be inadequate than the required reinforcement to resist the seismic forces which may cause the flexural and shear failure. In this study, a single 30 m-tall RC pier of a conventional bridge is examined under horizontal and vertical components of three separate earthquake records for three different deck to pier flexural stiffness ratios. Conventional bridges are constructed with movement joints and connections. The pier has a monolithic 15m-wide cap beam. The height of the cap beam is increased to provide different flexural stiffness ratios between column and cap beam. As the flexural stiffness of the cap beam is increased, the change in the column shear force and moment due to additional P-Δ effect of vertical component of earthquake is investigated. As a result, only the horizontal impact of the earthquake and the effect of both horizontal and vertical earthquakes are compared for the column forces. Secondly, the single pier of the conventional bridge with the same geometric properties is investigated for the cases that it is buried under 5 m, 10 m and 15 m of earth fill. The horizontal components of the same earthquake records are used in the analysis. Forcedeformation relation of the soil is represented by non-linear p-y springs for the buried cases.Item Preliminary seismic evaluation of highway bridges in Istanbul(Thesis (M.S.) - Bogazici University. Kandilli Observatory and Earthquake Research Institute, 1995., 1995.) Zülfikar, A. Can.; Yüzügüllü, Özal.In spite of the considerable developments in bridge engineering in recent years, substantial damages of highway bridges in recent earthquakes, have lead to an increasing awareness on the seismic performance of bridges. Seismic vulnerability of a bridge can be defined as the potential of a bridge to sustain significant damage or collapse. The seismicity at the location of the bridge is essential in the determination of its vulnerability. Istanbul is one of the most crucial cities in Turkey due to its historical, industrial and commercial importance. The main objective of the current study is to establish an inventory for the highway bridges on the 01 and 02 peripheral routes and the corresponding link roads in Istanbul and evaluate their seismic vulnerabilities according to a certain screening procedure. Such a preliminary screening procedure contemplates only the technical aspects of the problem and does not include political and economic considerations. In the preliminary screening process, Structural characteristics of the bridge, Importance of the bridge as a vital transportation link, Foundation and site characteristics of the bridge, are taken into consideration. In addition to the above studies, truck loading testing and a detailed analysis on a typical representitive bridge are presented. The results of this investigation are to be considered as the essential and basic step for the maintenance and rehabilitation of the ,highway bridges in istanbul under a future seismic activity.Item Seismic evaluation of Bolu viaduct 1(Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake research Institute, 2006., 2006.) Candan, B. Tolga.; Aydınoğlu, M. Nuray.A thesis is presented on the seismic evaluation of a viaduct using non-linear analysistechniques. The Bolu viaduct is a 2-3 km long seismically isolated structure with two parallelbridges each with a span length of 39.2 m and pier height of maximum 49 m that was nearly complete when it was struck by the 1999 Duzce earthquake in Turkey. With the design basedon AASHTO standards, it suffered complete failure of the seismic isolation system andnarrowly avoided total collapse due to excessive superstructure moment. After investigationsthe retrofit of the viaduct had been decided due to the study carried out by Michele Calvi and J. Nigel Priestley. This thesis concentrates on the retrofitted structure of Viaduct 1 by non-linear time historyanalysis.Item Seismic performance assessment of Ortaköy V409 viaduct(Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2007., 2007.) Öztürk, Ali Cem.; Aydinoğlu, M. Nuray.The Ortakoy V409 carries 1st Peripheral Highway and has constructed in 1973. The V409 is the last approach viaduct of First Bosphorous Bridge and has a specific role on transportation of stanbul. The existing condition, which is investigated on site, clearly shows that there are significiant damages like corrosions and etc. at whole structure due to lack of maintenance. The existing condition of structure has been evaluated by inelastic analysis method. In this dissertation, in part 1 the general descriptions have tried to be explained. In part 2; The existing conditions like dimensions and etc. have stated according to the site investigations and existing drawings. In the following part; the methods that were used in calculations explained. In part 4 the modelling procedure with the appropriate softwares and the loads that were applied in analyses have exhibited. In the final part the conclusions have stated. As a result of the time history analyses, like mentioned above, the viaduct is vulnearable due to deficiencies of ductility and detailing concepts. Existing sections can not resist the shear forces and moments occured during the earthquakes.Item Seismic performance evaluation of the Sadabat 1 (V3) viaduct(Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2002., 2002.) Önem, Göktürk.; Aydınoğlu, M. Nuray.Sadabat V3 was designed in the late 1980's as a connector highway bridge in conjunction of Okrneydam and Hastal on ball-Sakarya motonvay route, which is a major component of the transportation system of Istanbul. The bridge shows some typical examples of old seismic design philosophy such as low level of design forces and lack of modem ductile detailing. Based on the visual inspection, any detrimental effects such as cracking or spalling of cover concrete due to corrosion could not be observed. Generally, it can be say that current condition of the bridge is good. The bridge is evaluated as a critical bridge because of the location on major traveled route. The bridge is expected to remain functional immediately following a destructive earthquake. Seismic performance of the bridge has been assessed by using nonlinear time history analysis and pushover analysis. At the end of the analysis, deformation demand determined fi-om the analysis has been compared with the predetermined component deformation capacity to obtain whether the bridge provides expected performance. Analysis shows that elastomeric; bearings, particularly located on flexible intermediate piers have insufficient displacement capacities in transverse direction to remain elastic. Displacement ductility of the piers are inadequate due to the poor detailing of the plastic hinge region. Because of the low ductility capacity, the piers are unlikely to tolerate cyclic displacement much exceeding yield in transverse direction. However, it can be concluded that the bridge response is essentially elastic in longitudinal direction.Item Synthesis of earthquake ground motion at the 1915 Çanakkale Bridge :|stochastic simulations with a regional path duration function(Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2021., 2021.) Büyükçapar, Numan.; Tanırcan, Gülüm.Strong ground shaking duration has got to be taken into consideration realistically in ground motion simulations as it is a key parameter affecting structural damages. Total duration of an earthquake comprises source and path properties. Among them path duration which is one of the most important parameters for use in stochastic simulation studies has long been defined as multilinear functions of distance modelled with regional or global earthquake ground motion recordings. Up-to-date path duration models available in the literature are based on global (PEER-NGAWest2) or regional (such as NEAmerica, Japan) strong motion database. Therefore, they represent either a global estimation or can be used only for certain regions. Turkey-specific path duration-distance function is absent in the scientific literature. The main purpose of this thesis is to fulfill this absence and propose a path duration-distance function utilizing the abundant strong motion database of Turkey as well as performing stochastic simulation of strong ground motions at the 1915 Çanakkale Bridge by using path duration function that describes the behavior of Turkish earthquakes. For the latter part of the study, a stochastic simulation method of Motazedian and Atkinson (2005): EXSIM is utilized. Effect of generic and site-specific local site amplification on the simulation is another subject that is investigated in the thesis. Subsequent to this suggestion, the said original method, which is also present on the SCEC (Southern California Earthquake Center) Broadband Platform, was improved by Boore (2009) and Assatourians and Atkinson (2012). Following the analyses which are intrinsic to above-mentioned parts of the study, the obtained regional path duration function has been discussed in detail, and simulations that have been performed throughout the thesis have been thoroughly assessed and presented.