Civil Engineering
http://hdl.handle.net/10679/312
2024-03-29T08:36:47Z
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Effect of flexural demands in the leaner columns on the column buckling strength
http://hdl.handle.net/10679/9304
Effect of flexural demands in the leaner columns on the column buckling strength
Özçelik, Ahmet Yiğit; Clayton, P. M.
Leaner columns of steel frames are typically designed for axial load only and they are assumed not to contribute to the lateral stiffness of the system; however, a recent study revealed that under seismic loading leaner columns underwent significant flexural demands due to differential interstory drift demands along the building height that were not observed when traditional design methods were adopted. A parametric numerical study is conducted to quantify the reduction in column buckling strength due to these flexural demands that are not considered in design. An empirical column buckling strength reduction factor that accounts for the reduction in the column buckling strength due to flexural demands is proposed. This reduction factor can be easily implemented with traditional design approaches without considering the flexural demands in the leaner columns explicitly.
2018-01-01T00:00:00Z
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Tension field inclination angle in steel plate shear walls with beam- connected web plates
http://hdl.handle.net/10679/9284
Tension field inclination angle in steel plate shear walls with beam- connected web plates
Özçelik, Ahmet Yiğit; Clayton, P.
Steel plate shear walls (SPSWs) are an efficient lateral force-resisting system with thin infill plates, main elements resisting the lateral force, connected to beams and columns on all four edges. Upon lateral loading, thin infill plates (also known as web plates) buckle almost immediately; however, the lateral stiffness and lateral strength of SPSWs are maintained due to a mechanism called tension field action. Steel plate shear walls with beam-connected web plates (B- SPSWs) are an alternative SPSW configuration where the web plates are detached from columns and connected to beams only. As opposed to conventional SPSWs where the full tension field is observed, a partial tension field is developed in the web plates of B-SPSWs due to the difference in connectivity which alters the system behavior significantly. As SPSWs are typically modeled using simplified strip models in which the accurate determination of the tension field inclination angle is of paramount importance, an analytical study is undertaken to quantify the partial tension field inclination angle. Using validated finite element models, beam-connected web plate behavior is characterized, and an equation is proposed for the partial tension field inclination angle.
2019-01-01T00:00:00Z
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A new embankment construction method through the analysis of possible failure mechanisms in soft soils
http://hdl.handle.net/10679/9281
A new embankment construction method through the analysis of possible failure mechanisms in soft soils
Arama, Z. A.; Çinicioğlu, Safiye Feyza
A new method to analyze the failure behavior of embankments on soft soils is proposed in this paper. The proposed method is based on the evaluation of stability considerations applied on a possible mechanism which can be initiated by embankment loading. The developed procedure is applied on a successive set of failure mechanisms that extend towards depth starting from the surface. The envisaged mechanism is made up of concentric half circles starting from the toe of the embankment and spreading towards the deeper soils. By partitioning the circular strips by a slip fan system originating from the center of concentric circles a system of collapse mechanism partitioned to produce finite elements is created. Available stress values at each element are found by applying the rules of the lower bound plasticity solution. Once the stresses and the dimensions of the constructed mechanism are defined stability calculations are made to find the critical depth that will result in failure for any desired embankment height. Moreover safety factors mobilized at lower depths can be calculated. © The authors and IGS: All rights reserved, 2019.
2019-01-01T00:00:00Z
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Two-part bio-based self-healing repair agent for cement-based mortar
http://hdl.handle.net/10679/9253
Two-part bio-based self-healing repair agent for cement-based mortar
Tezer, Mustafa Mert; Bundur, Zeynep Başaran
Factors affecting durability of concrete structures are generally associated with each other. Due to its brittle nature, concrete can crack under stress and these cracks are one of the main reasons for a decrease in service life in concrete structures. Therefore, it is crucial to detect and recover microcracks, then to repair them as they were developed to wider cracks. Recent research in the field of concrete materials suggested that it might be possible to develop a smart cement-based material that is capable of remediate cracks by triggering biogenic calcium carbonate (CaCO3) precipitaton. This paper summarizes a study undertaken to investigate the self-healing efficiency of Sporosarcina pasteurii (S. pasteurii) cells immobilized on both diatomaceous earth and pumice, to remediate flexural cracks on mortar in early ages (28 days after mixing). To obtain a two-phase bio additive, half of the minerals were saturated with a nutrient medium consisting of urea, corn-steep liqueur(CSL) and calcium acetate and the cells with immobilized to the other half without nutrients. Screening of the healing process was done with ultrasonic pulse velocity (UPV) testing and stereomicroscopy. With this approach, the cracks on mortar surface were sealed and the water absorption capacity of the so-called self-healed mortar decreased compared to its counterpart cracked mortar samples.
2020-01-01T00:00:00Z