• Journal of the Society of Disaster Information
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• v.12 no.2
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• pp.144-149
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• 2016

Nowaday, most of the low-rise concrete structures which have less than five stories were built before the intensified seismic code was established 2005. According to the fact that our country is not a safety zone ay more, studies are need to reinforce the seismic performance of that structures. The basic frame of low-rise structure are consist of beams and columns with partition walls, therefore that are very weak about secondary wave of earthquake because of the high stiffness. The partition wall are consist of open channel for sunlight or ventilation and intermediate wall. The intermediate walls will enhance the stiffness of columns, but will cause shear failure with short column effects because of the reduced effective depth. But we don't have studies and adequate design code for partition wall effects, therefore some more studies are need for these facts.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.125-133
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• 2007

External confinement by CFS (Carbon Fiber Sheet) is a very effective retrofit method for the reinforced concrete columns subject to either static or seismic loads. For the reliable and cost-effective design of CFS, an accurate stress-strain curve is required for CFS-confined concrete. In this paper, uniaxial compression test on short RC column with circular section was performed. To evaluate the effect of confinement on the stress-strain relationship of CFS-confined concrete, CFS area ratio, spiral area ratio, and concrete compressive strength are considered as the test variables. Experiment results indicate that CFS jacketing significantly enhances strength and ductility of concrete. In addition, the CFS-jacketed specimens with the spiral steel show the lower load increasement ratio than those without the spiral steel.

• Structural Engineering and Mechanics
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• v.69 no.3
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• pp.257-268
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• 2019

Infills are as important members in structural design as beams, columns and braces. They have significant effect on structural behavior. Because of lots of variables in infills like material non-linear behavior, the interaction between frames and infill, etc., the infills performance during an earthquake is complicated, so have led designers do not consider the effect of infills in designing the structure. However, the experimental studies revealed that the infills have the remarkable effect on structure behavior. As if these effects ignored, it might occur soft-story phenomena, torsion or short-column effects on the structures. One simple and appropriate method for considering the infills effects in analyzing, is replacing the infills with diagonal compression strut with the same performance of real infill, instead of designing the whole infill. Because of too many uncertainties, codes and researchers gave many expressions that were not as the same as the others. The major intent of this paper is calculation the width of this diagonal strut, which has the most characteristics of infill. This paper by comprehensive on different parameters like the modulus of young or moment of inertia of columns presents a new formula for achieving the equivalent strut width. In fact, this new formula is extracted from about 60 FEM analyses models. It can be said that this formula is very efficient and accurate in estimating the equivalent strut width, considering the large number of effective parameters relative to similar relationships provided by other researchers. In most cases, the results are so close to the values obtained by the FEM. In this formula, the effect of out of plane buckling is neglected and this formula is used just in steel structures. Also, the thickness of infill panel, and the lateral force applied to frame are constant. In addition, this new formula is just for modeling the lateral stiffness. Obtaining the nearest response in analyzing is important to the designers, so this new formula can help them to reach more accurate response among a lot of experimental equations proposed by researchers.

• Earthquakes and Structures
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• v.20 no.3
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• pp.325-335
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• 2021

The majority of Turkey's geography is at risk of earthquakes. Within the borders of Turkey, including the two major active faults contain the North-Eastern and Eastern Anatolia, earthquake, threatening the safety of life and property. On January 24, 2020, an earthquake of magnitude 6.8 occurred at 8:55 p.m. local time. According to the data obtained from the stations in the region, peak ground acceleration in the east-west direction was measured as 0.292 g from the 2308 coded station in Sivrice. It is thought that the earthquake with a magnitude of Mw 6.8 was developed on the Sivrice-Puturge segment of the Eastern Anatolian Fault, which is a left lateral strike slip fault, and the tear developed in an area of 50-55 km. Aftershocks ranging from 0.8 to 5.1 Mw occurred following the main shock on the Eastern Anatolian Fault. The earthquake caused severe structural damages in Elazığ and neighboring provinces. As a result of the field investigations carried out in this study, significant damage levels were observed in the buildings since it did not meet the criteria in the earthquake codes. Within the study's scope, the structural damage cases in reinforced concrete and masonry structures were investigated. Many structural deficiencies and mistakes such as non-ductile details, poor concrete quality, short columns, strong beams-weak columns mechanism, large and heavy overhangs, masonry building damages and inadequate reinforcement arrangements were observed. Requirements of seismic codes are discussed and compared with observed earthquake damage.

• Steel and Composite Structures
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• v.44 no.3
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• pp.295-307
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• 2022

The objective of this research is to study experimentally the behavior of stiffened steel tubes (CFSTs). Considered parameters are stiffening methods by through-bolts or shear connectors with different configurations. In addition, the effect of global (ratio between length to diameter) and local (proportion between diameter to thickness) slenderness ratios are investigated. Load application either applied on steel only or both steel and concrete is studied as well. Case of loading on steel only happens when concrete inside the column shrinks. The purpose of the research is to improve the behavior of CFSTs by load transfer between them and different stiffening methods. A parametric experimental study that incorporates thirty-three specimens is carried out to highlight the impact of those parameters. Different outputs are recorded for every specimen such as load capacities, vertical deflections, longitudinal strains, and hoop strains. Two modes of failure occur, yielding and global buckling. Shear connectors and through-bolts improve the ultimate load by up to 5% for sections loaded at steel with different studied global slenderness and local slenderness equal 63.5. Meanwhile, shear connectors or through bolts increase the ultimate load by up to 6% for global slenderness up to 15.75 for sections loaded on composite with local slenderness equals 63.50. Recommendations for future design code development are outlined.

• Journal of the Korean Institute of Rural Architecture
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• v.24 no.2
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• pp.13-20
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• 2022

In this study, a general low-rise building was selected to compare the new shear wall reinforcement method, which is a general method among the existing reinforcement methods, and the reinforcement method using sinusoidal corrugated web reinforcement. And it was confirmed that the following effects can be expected. Sinusoidal corrugated web members can be carried out in a short period of time as it does not require the removal of the masonry filling wall, the reinforcement of reinforcing bars, and the curing period of the concrete. It is effective in preventing damage that may occur when masonry filling wall is overturned in the out-of-plane direction, and the burden of the foundation is also reduced, and thus the construction period and cost required for reinforcement can greatly be reduced. By adjusting the number of sinusoidal corrugated web member, details of joints, and reinforcement positions, the flow of load can be induced to have an advantageous effect on the building. It can be considered as the most suitable reinforcement plan in terms of life safety. Unlike the shear wall that fills between the columns, the sinusoidal corrugated web members, which has a width of 1.5m, can install openings between two columns depending on the purpose of use, and can be expected to have a great effect in terms of usability due to its free installation location. As mentioned above, the seismic reinforcement using a sinusoidal corrugated web members, can expect great effect compared to conventional reinforcement methods in terms of usability, economic feasibility, and stability.

• Proceedings of the Korean Society of Toxicology Conference
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• 2006.11a
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• pp.65-74
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• 2006

Modem drug discovery requires rapid pharmacokinetic evaluation of chemically diverse compounds for early candidate selection. This demands the development of analytical methods that offer high-throughput of samples. Naturally, liquid chromatography / tandem mass spectrometry (LC-MS/MS) is choice of the analytical method because of its superior sensitivity and selectivity. As a result of the short analysis time(typically 3-5min) by LC-MS/MS, sample preparation has become the rate- determining step in the whole analytical cycle. Consequently tremendous efforts are being made to speed up and automate this step. In a typical automated 96-well SPE(solid-phase extraction) procedure, plasma samples are transferred to the 96-well SPE plate, internal standard and aqueous buffer solutions are added and then vacuum is applied using the robotic liquid handling system. It takes only 20-90 min to process 96 samples by automated SPE and the analyst is physically occupied for only approximately 10 min. Recently, the ultra-high flow rate liquid chromatography (turbulent-flow chromatography)has sparked a huge interest for rapid and direct quantitation of drugs in plasma. There is no sample preparation except for sample aliquotting, internal standard addition and centrifugation. This type of analysis is achieved by using a small diameter column with a large particle size(30-5O ${\mu}$m) and a high flow rate, typically between 3-5 ml/min. Silica-based monolithic HPLC columns contain a novel chromatographic support in which the traditional particulate packing has been replaced with a single, continuous network (monolith) of pcrous silica. The main advantage of such a network is decreased backpressure due to macropores (2 ${\mu}$m) throughout the network. This allows high flow rates, and hence fast analyses that are unattainable with traditional particulate columns. The reduction of particle diameter in HPLC results in increased column efficiency. use of small particles (<2 urn), however, requires p.essu.es beyond the traditional 6,000 psi of conventional pumping devices. Instrumental development in recent years has resulted in pumping devices capable of handling the requirements of columns packed with small particles. The staggered parallel HPLC system consists of four fully independent binary HPLC pumps, a modified auto sampler, and a series of switching and selector valves all controlled by a single computer program. The system improves sample throughput without sacrificing chromatographic separation or data quality. Sample throughput can be increased nearly four-fold without requiring significant changes in current analytical procedures. The process of Bioanalytical Method Validation is required by the FDA to assess and verify the performance of a chronlatographic method prior to its application in sample analysis. The validation should address the selectivity, linearity, accuracy, precision and stability of the method. This presentation will provide all overview of the work required to accomplish a full validation and show how a chromatographic method is suitable for toxirokinetic sample analysis. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method developed to quantitate drug levels in dog plasma will be used as an example of tile process.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.73-76
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• 2008

According to the survey of earthquake disaster, low-rise reinforced concrete building larger by the extent of damage and because of the underlying distribution of reinforced concrete structures more, it is very likely to be disasters. The purpose of this study is to discuss how strength and stiffness of each system in low-rise reinforced concrete buildings consisted of extremely brittle, shear and flexural failure lateral-load resisting systems have influence on seismic capacities of the overall system. Generally, if shear failure members including extremely brittle failure members are failed during an earthquake, the lateral-load resisting seismic capacities of RC buildings are lower rapidly, and if the seismic capacities of shear failure members were higher than that of flexural failure members, failures of shear failure members have influence on failures of the overall system. The result of this paper will provide pseudo-dynamic test of carried out to estimate the possibility of proposals.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.233-241
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• 2005

The paper is presented experimental study results on bond stress between profiled steel and concrete in Profiled SPC(Profiled Steel Plate Concrete) rectangular steel tubes through an experimental program in which 13 pull-out specimens were tested. Advantages and class of composite members and current problems of construction work are noted, past research of PSSC is described. An experimental study is described and evaluated. The bond capacity is interrelated with slip at the steel concrete interface. The factors influencing the mechanism of bond stress transfer were the cross section shape, length/diameter, diameter/thickness and environmental parameters (temperature, moisture). The results of experimental program indicated that the force transfer could be characterized into two regions The first region was governed by bond with no relative slip between the profiled steel and concrete. The second region occurs after the chemical debonding. Bond stress transfer in this region was governed by frictional resistance between profiled steel and concrete and cross section shapes. The important factors influencing the magnitude of frictional resistance are the profiled steel shapes, length/diameter and environmental parameters. (temperature, moisture)

• Steel and Composite Structures
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• v.47 no.6
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• pp.709-728
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• 2023

Experimental and analytical studies were conducted to clarify the influencing mechanisms of the longitudinal reinforcement on performance of axially loaded Reinforced Concrete-Filled Steel Tube (R-CFST) short columns. The longitudinal reinforcement ratio was set as parameter, and 10 R-CFST specimens with five different ratios and three Concrete-Filled Steel Tube (CFST) specimens for comparison were prepared and tested. Based on the test results, the failure modes, load transfer responses, peak load, stiffness, yield to strength ratio, ductility, fracture toughness, composite efficiency and stress state of steel tube were theoretically analyzed. To further examine, analytical investigations were then performed, material model for concrete core was proposed and verified against the test, and thereafter 36 model specimens with four different wall-thickness of steel tube, coupling with nine reinforcement ratios, were simulated. Finally, considering the experimental and analytical results, the prediction equations for ultimate load bearing capacity of R-CFSTs were modified from the equations of CFSTs given in codes, and a new equation which embeds the effect of reinforcement was proposed, and equations were validated against experimental data. The results indicate that longitudinal reinforcement significantly impacts the behavior of R-CFST as steel tube does; the proposed analytical model is effective and reasonable; proper ratios of longitudinal reinforcement enable the R-CFSTs obtain better balance between the performance and the construction cost, and the range for the proper ratios is recommended between 1.0% and 3.0%, regardless of wall-thickness of steel tube; the proposed equation is recommended for more accurate and stable prediction of the strength of R-CFSTs.