İnşaat Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1943

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Citation - WoS: 1
Citation - Scopus: 1
A Simplified Approach for Site-Specific Design Spectrum
(2018) Tönük, Gökçe; Kurtuluş, Aslı; Ansal, Atilla
The design acceleration spectrum requires site investigations and site-response analyses in accordance with the local seismic hazard. The variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the earthquake hazard. An important step is the selection and scaling of input acceleration records. Likewise, a large number of soil profiles need to be considered to account for the variability of site conditions. One option is to use Monte Carlo simulations with respect to layer thickness and shear wave velocity profiles to account for the variability of the site factors. The local seismic hazard analysis yields a uniform hazard acceleration spectrum on the bedrock outcrop. Site-specific response analyses also need to produce a uniform hazard acceleration spectrum on the ground surface. A simplified approach is proposed to define acceleration design spectrum on the ground surface that may be considered a uniform hazard spectrum.
An Overview on the Structural Monitoring, Assessment and Retrofitting of Historical Structures With a Focus on 13th Century Monuments
(Springer international Publishing Ag, 2024) Ilki, Alper; Inci, Pinar; Halici, Omer F.; Demir, Cem; Comert, Mustafa; Kuran, Fikret
Monumental historical structures affirm natural and cultural identity and hence they should be transmitted to future generations. The protection and preservation of these structures against aging and natural hazards, particularly seismic actions, requires a comprehensive approach including diagnosis of the present condition of the structure and enhancement of structural capacity for disaster mitigation, if necessary. It is obvious that due to their historical values, any attempt towards the preservation of the monumental historical structures must be carried out with respect to the principles of integrity and authenticity. In this study, the structural performance assessment procedures, implementation of structural health monitoring systems and seismic strengthening strategies are discussed and described with reference to 13th-century monumental historical structures in Turkiye. The structural engineering aspects of recent activities for the restoration and preservation of the Great Mosque and Hospital of Divrigi (a world heritage listed structure) and Sivas Ulu Cami (Mosque) Minaret are briefly presented. In light of the structural analysis and monitoring results, recommendations for interventions to these monumental structures are outlined.
Citation - WoS: 1
Citation - Scopus: 2
Compaction and Shear Strength Behavior of Fresh and Aged Basic Oxygen Furnace (bof) Steel Slag
(2016) Yıldırım, İrem Zeynep; Prezzi, Monica
Use of industrial by-products in geotechnical engineering projects, such as in the construction of highway embankments, is advantageous because large volumes of these materials can be utilized. Basic oxygen furnace (BOF) steel slag is one of these industrial by-products. This paper provides a brief background on the characteristics of BOF steel slag and presents the results of a series of laboratory tests (grain-size analysis, maximum and minimum dry density, compaction, large-scale direct shear tests (LDS) and isotropically consolidated-drained triaxial compression (CID TX) performed on fresh and aged BOF steel slag generated from an Indiana steel plant. BOF steel slag samples from three different batches of production were tested, which allowed an evaluation of both aging processes and the effect of changes in gradation on the mechanical properties. The BOF steel slag tested in this study contained sand-size particles with varying percentages of gravel-and silt-size fractions. The moisture-density relationships for BOF steel slag were irregular with two peaks. Based on the LDS and CID TX test results, the BOF steel slag exhibited superior strength and stiffness characteristics than conventional geo-materials. The mechanical properties of fresh and aged BOF steel slag are discussed in the context of its use in geotechnical applications.
Citation - WoS: 2
Citation - Scopus: 1
Eaf Ladle Steel Slag as a Geo-Material: Compaction and Shear Strength Characteristics
(2018) Yıldırım, İrem Zeynep; Prezzi, Monica
The numerous issues associated with the excess steel slag that is disposed of in landfills every year can be reduced by using it as a geo-material. This paper provides the results of laboratory tests (i.e., sieve, hydrometer, specific gravity, compaction, compaction-particle degradation, and large-scale direct shear with a box size of 30.5 x 30.5 x 20 cm) performed on electric-arc-furnace ladle [EAF(L)] steel slag from a mini-mill in Indiana. Based on standard proctor test results, the maximum dry unit weight values of the EAF(L) steel slag were in the 16.8-to-20 kN/m(3) range at the optimum moisture contents of 11-13%. The results of the large-scale direct shear tests performed on EAF(L) steel slag, compacted at 95-100% relative compaction and sheared with normal stress ranging from 50 to 300 kPa, showed that it has excellent frictional characteristics, with friction angles between 40 and 45 degrees. Based on the results from this study, due to its shear strength characteristics, EAF(L) steel slag has the potential to be utilized as a geo-material to improve the shear strength of various marginal soils.
Citation - WoS: 3
Citation - Scopus: 2
Near-Fault Earthquake Ground Motion and Seismic Isolation Design
(Springer International Publishing Ag, 2023) Harmandar, Ebru; Erdik, Mustafa; Demircioglu-Tumsa, Mine B.; Şadan, Bahadır; Tuzun, Cuneyt; Ulker, Omer
Seismic isolation is one of the most reliable passive structural control techniques with adequately established standards for the earthquake protection of structures from earthquakes. However, it has been shown that the seismic isolation systems may not function the best for the near-fault ground motions, since in the proximity of a capable fault, the ground motions are significantly affected by the rupture mechanism and may generate high demands on the isolation system and the structure. In fact, several earthquake resistant design codes state that the seismically isolated structures located at near-fault sites should be designed by considering larger seismic demands than the demand on structures at far-field sites. When the fault ruptures in forward direction to the site most of the seismic energy arrives in coherent long-period ground velocity pulses. The ground-motion prediction equations (GMPEs) typically cannot account for such effects with limited distance metrics and lack adequate data at large magnitudes and near distances. For the reliable earthquake design of the isolated structure in near fault conditions that meets the performance objectives, the 3D design basis ground motion(s) need to be appropriately assessed. Measures in the design of the isolation system, such as modifications in the stiffness and damping characteristics, as well as in the limitation of vertical effects are needed. The behavior of the base-isolated buildings under near-fault (NF) ground motions with fling-step and forward-directivity characteristics are investigated with a rational assessment of design-basis near-fault ground motion, are investigated in a parametric format. The parametric study includes several variables, including the structural system flexibility; number of stories; isolation system characteristic (yield) strength, and the isolation periods related to the post-elastic stiffness. Furthermore, the effect of additional damping by viscous dampers were tested for some selected cases. Important findings observed from the parametric performance results and the overall conclusions of the study are provided.
Citation - WoS: 4
Citation - Scopus: 4
State of the Art in Application of Seismic Isolation and Energy Dissipation in Turkey
(Springer International Publishing Ag, 2023) Şadan, Bahadır
This paper summarizes the passive structural control system applications and other related developments in Turkey, emphasizing the period between 2019 and 2022. The country hosts state-of-the-art seismic isolation applications, relatively greater in size, and use more isolators in each project (415 isolators per building on average) compared to the other seismic isolation projects worldwide. Construction of the world's largest seismic isolated building, Istanbul Basaksehir Pine and Sakura City Hospital, covering more than 1 million square meters of area and employing more than 2000 seismic isolators, was completed and has been in service since May 2020. 1915 Canakkale Bridge, constructed in memory of the great war of Canakkale during World War I, is now the world's longest suspension bridge with a 2023m main span length. Eight massive hydraulic dampers were used at the main deck and 48 at the approach viaducts in combination with 72 seismic isolators. Construction of a residential building complex in Istanbul consisting of 16 isolated blocks covering more than 170,000 m(2) area and having 454 seismic isolators is coming to an end very soon. Historical Nusretiye Clock Tower in Istanbul was relocated a few meters over seismic isolators. Historical Goztepe Railway Station in Istanbul was retrofitted to accommodate an additional railway line using seismic isolation technology. Seismic codes for buildings and bridges now include rules for the seismically isolated design of structures. Additionally, all seismic isolation designs must be peer-reviewed by law. A new seismic isolator testing facility was established in Eskisehir to respond to the demand for the large number of isolators that need to be tested.

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