Browsing by Author "Tapan, M."

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Compressive Strength of Scoria Added Portland Cement Concretes
(Gazi Univ, 2012) Ozvan, A.; Tapan, M.; Erik, O.; Efe, T.; Depci, T.
This paper presents the results of preliminary studies investigating the potential effects of using scoria as supplementary and its amount on compressive strength of concrete. Concrete mixtures containing 5, 10, 20, 30, 40 and 50 % scoria type natural pozzolan by mass of the total cementitious material were prepared. In addition, a conventional portland cement concrete mixture with the same w/cm ratio was prepared as a reference. Preliminary results indicated that the compressive strength of the concrete mixtures with scoria added up to 30% exceeded the strength of the conventional mixture at 3, 7, 28 and 91 days, whereas the compressive strength of the 40 and 50% scoria added concrete mixtures decreased at 3, 7, 28 and 91 days. It was found that early strength of scoria added (up to 30%) concrete mixtures showed higher compressive strengths up to 112%.
Determination of Dynamic Soil Properties of Van Yuzuncu Yil University Campus for the Preparation of Microzonation Map
(TMMOB - Jeoloji Muhendisleri Odasi, 2015) Akin, M.K.; Akin, M.; Akkaya, İ.; Özvan, A.; Üner, S.; Selçuk, L.; Tapan, M.
One of the most important factors causing loss of life and property during earthquakes is the soil conditions that the structure is built on. Determination of the soil engineering properties for understanding the behavior of ground under dynamic loads and/or minimizing the losses that may occur is quite crucial. The earthquakes occured in our country especially in 1999 and later on, and the resulting loss of life and property once more emphasized the importance of the social and economic dimensions of the impact created by the earthquake. Dynamic soil properties must be studied in accordance with the principles of microzonation considering the natural disasters such as earthquake. For this aim, the dynamic soil properties of Van Yuzuncu Yil University campus area are determined. Liquefaction, soil amplification and the like for the campus area are investigated through field studies conducted in order to reveal the ground conditions, and consequently the suitability for settlement is evaluated to guide the future planning of the campus. © 2015, TMMOB - Jeoloji Muhendisleri Odasi. All Rights Reserved.
Effect of Steel Corrosion and Loss of Concrete Cover on Strength of Deteriorated Rc Columns
(Elsevier Sci Ltd, 2011) Tapan, M.; Aboutaha, R. S.
In this paper, the effect of reinforcement corrosion and loss of concrete cover on structural behavior of bridge columns is quantified by developing moment-axial load (M-P) interaction diagrams using modified analysis procedure and advanced deteriorated material models. The results of this study suggest that corrosion of steel bars on the compression side of column section reduces the effective depth, and causing more reduction than left side or tension side deterioration, in compression controlled region. However, in general, corrosion of tension reinforcement causes more strength reduction than corrosion of reinforcement in compression or left/right side reinforcement, particularly, in tension controlled region. (C) 2010 Elsevier Ltd. All rights reserved.
Effect of Viscous Damping Devices on the Response of Seismically Isolated Structures
(Wiley, 2015) Wolff, E. D.; Ipek, C.; Constantinou, M. C.; Tapan, M.
Viscous and other damping devices are often used as elements of seismic isolation systems. Despite the widespread application of nonlinear viscous systems particularly in Japan (with fewer applications in the USA and Taiwan), the application of viscous damping devices in isolation systems in the USA progressed intentionally toward the use of supplementary linear viscous devices due to the advantages offered by these devices. This paper presents experimental results on the behavior of seismically isolated structures with low damping elastomeric (LDE) and single friction pendulum (SFP) bearings with and without linear and nonlinear viscous dampers. The isolation systems are tested within a six-story structure configured as moment frame and then again as braced frame. Emphasis is placed both on the acquisition of data related to the structural system (drifts, story shear forces, and isolator displacements) and on non-structural systems (floor accelerations, floor spectral accelerations, and floor velocities). Moreover, the accuracy of analytical prediction of response is investigated based on the results of a total of 227 experiments, using 14 historic ground motions of far-fault and near-fault characteristics, on flexible moment frame and stiff braced frame structures isolated with LDE or SFP bearings and linear or nonlinear viscous dampers. It is concluded that when damping is needed to reduce displacement demands in the isolation system, linear viscous damping results in the least detrimental effect on the isolated structure. Moreover, the study concludes that the analytical prediction of peak floor accelerations and floor response spectra may contain errors that need to be considered when designing secondary systems. Copyright (c) 2014 John Wiley & Sons, Ltd.
Evaluation of Ultimate Capacity of Deteriorated Reinforced Concrete Bridge Columns
(CRC Press, 2008) Tapan, M.; Aboutaha, R.S.
Load Carrying Capacity of Deteriorated Reinforced Concrete Columns
(Techno Press, 2009) Tapan, M.; Aboutaha, R.S.
This paper presents a new methodology to evaluate the load carrying capacity of deteriorated non-slender concrete bridge pier columns by construction of the full P-M interaction diagrams. The proposed method incorporates the actual material properties of deteriorated columns, and accounts for amount of corrosion and exposed corroded bar length, concrete loss, loss of concrete confinement and strength due to stirrup deterioration, bond failure, and type of stresses in the corroded reinforcement. The developed structural model and the damaged material models are integrated in a spreadsheet for evaluating the load carrying capacity for different deterioration stages and/or corrosion amounts. Available experimental and analytical data for the effects of corrosion on short columns subject to axial loads combined with moments (eccentricity induced) are used to verify the accuracy of proposed model. It was observed that, for the limited available experimental data, the proposed model is conservative and is capable of predicting the load carrying capacity of deteriorated reinforced concrete columns with reasonable accuracy. The proposed analytical method will improve the understanding of effects of deterioration on structural members, and allow engineers to qualitatively assess load carrying capacity of deteriorated reinforced concrete bridge pier columns.
Mechanical Characteristics of Pumice-Based Geopolymer Paste
(Elsevier B.V., 2020) Safari, Z.; Kurda, R.; Al-Hadad, B.; Mahmood, F.; Tapan, M.
One way to promote sustainability is by using high volume of by-product materials in construction materials, namely by geopolymerization. For that purpose, other studies have focused on the common supplementary cementitious materials (e.g. fly ash and metakaolin) as a precursor. However, there are other potential types of precursor can also be used for geopolymerization purpose. Thus, this study used pumice powder, which is rich in Silica and Aluminium, to produce geopolymer paste. For activation by alkali solution, the ratios of “sodium silicate to sodium hydroxide” and “alkali solution to precursor” was fixed at 2.50 and 0.35, respectively. To find optimum molarity, curing temperature and curing period, the pastes made with different alkali concentration (8, 10, 12, 14, 16 and 18 M) and cured at room temperature, 60, 80 and 100 °C temperature for 24, 48, 72 and 120 h. The results showed that optimum flexural and compressive strength can be made for the mixes at 60 °C of oven curing for 120 h with the alkali solution of 12 M. Additionally, high-strength paste can be obtained at high curing temperatures with less curing time, but when compared to low temperature and more curing time, the flexural and compressive strength gains are less. © 2020
Performance Based Rapid Seismic Assessment Method (Pera) for Reinforced Concrete Frame Buildings
(Sage Publications inc, 2014) Ilki, A.; Comert, M.; Demir, C.; Orakcal, K.; Ulugtekin, D.; Tapan, M.; Kumbasar, N.
Recent destructive earthquakes have shown that many existing buildings, particularly in developing countries, are not safe against seismic actions. Since code-based seismic safety evaluation methods generally require detailed and complex structural analysis, the necessity for simplified, yet sufficiently accurate evaluation methods emerges for reducing cost and duration of assessment procedures. In this study, a performance based rapid seismic safety assessment method (PERA) is proposed for reinforced concrete buildings. The overall structural performance is determined based on the demand/capacity ratios of individual columns, as well as their failure modes (brittle/ductile), confinement characteristics, and levels of axial and shear stresses. The lateral drift of the critical story, calculated through a simplified approach, is also taken into account during determination of the global structural performance. The predictions of this method are compared with the results of conventional detailed seismic safety assessment analyses carried out for 672 different cases representing typical reinforced concrete frame buildings in Turkey. Good agreement is obtained between the predictions of the proposed algorithm and code-based structural performance assessment procedures. Finally, predictions of the proposed approach are compared with actual damages observed in 21 existing buildings in Turkey after destructive earthquakes that have occurred during the last two decades. These comparisons also point to an acceptable level of accuracy and sufficient conservatism for the methodology proposed.
Performance of a Seismically Isolated Building in the Earthquakes of February 6, 2023, in Türkiye
(American Society of Civil Engineers (ASCE), 2025) Kim, H.-M.; Ipek, C.; Tapan, M.; Constantinou, M.C.
On February 6, 2023, a devastating earthquake of M7.8 struck Türkiye with an epicenter to the east of the city of Gaziantep. Within hours, it was followed by a M7.5 earthquake some 107 km to the north. The focus of this paper is the performance of a seismically isolated hospital in Adana at distance of 158 km to the east of the epicenter of the M7.8 earthquake. Despite the large distance from the epicenter, the ground shaking was large enough to activate the triple friction pendulum isolators of the building, resulting in a beneficial reduction of accelerations directly above the isolators and avoidance of any structural or nonstructural damage. After baseline correction and filtering of the raw data of the instruments at the hospital, we obtained, by integration of acceleration records, estimates the isolator displacement histories. We performed analysis of the building using properties of the isolators obtained from the production tests on all 1,512 isolators and then adjusting the properties for their 8-year age. Based on comparison of the analysis results and processed records of the building's acceleration and displacement histories, we obtained estimates of isolator properties and confirmed that the isolators primarily responded with motion of the first pendulum (or in Regime I), which is characterized by high stiffness and low friction, leading to some reduction of response in weak seismic ground motion. © 2025 American Society of Civil Engineers.
The Role of Capillary Water Absorption Characteristics of Ignimbrites on the Deterioration of Ahlat Seljuk Tombstones
(TMMOB - Jeoloji Muhendisleri Odasi, 2016) Akin, M.; Dinçer, İ.; Özvan, A.; Oyan, V.; Tapan, M.
The Seljuk Tombs of the Seljuk Empire in the Ahlat region are included in UNESCO’s World Heritage Tentative List due to the fact that the tombstones are known to be the largest graveyards of Muslims with their historical significance. Tombstones were erected using ignimbrite type pyroclastic rocks which are widespread in the region, and several inscriptions and patterns were carved on them thanks to their softness and easy processing. However, these tombstones have been subjected to weathering effects for almost a duration of 800 years. The most striking point after the inspection of tombstones is that many of them were broken from the middle section. In this study, experimental studies were carried out on fresh ignimbrite specimens and particularly the effect of capillary water absorption on deterioration was investigated to reveal the factors leading to deterioration of Ahlat Seljuk tombstones. Accordingly, high porosity and capillary water absorption characteristics of the ignimbrites are found to be the major reasons for the deterioration of tombstones. © 2016, TMMOB - Jeoloji Muhendisleri Odasi. All rights reserved.
Structural Response of Reinforced Concrete Wide Beams Reinforced With Lattice Girders
(Shiraz Univ, 2014) Tapan, M.
This paper summarizes the test data obtained from an experimental investigation of reinforced concrete (RC) wide beams reinforced with lattice girders, which can also be described as one-way slabs, under low-rate (static) concentrated loading applied at their mid-span. Tests were conducted on lattice girder reinforced and traditionally reinforced beam-type specimens to investigate the effect of lattice girder on load carrying capacity. Key aspects of structural response such as the load deflection behavior, crack patterns, strength and failure modes of the tested beams were recorded and given in this paper. A total of 6 beams with two different reinforcement arrangements were tested. Tested beams were simply supported at a span of 2250 mm. All specimens were tested under static loading and midspan deflections were recorded using a displacement transducer. Similar stiffness was displayed by the lattice girder reinforced and traditionally reinforced beams, but higher resistant capacity was shown by the lattice girder reinforced beams.