• Coupled systems mechanics
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• v.6 no.4
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• pp.417-437
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• 2017

This paper shows a comparative study for design of reinforced concrete boundary combined footings of trapezoidal and rectangular forms supporting two columns and each column transmits an axial load and a moment around of the axis X (transverse axis of the footing) and other moment around of the axis Y (longitudinal axis of the footing) to foundation to obtain the most economical combined footing. The real soil pressure acting on the contact surface of the footings is assumed as a linear variation. Methodology used to obtain the dimensions of the footings for the two models consider that the axis X of the footing is located in the same position of the resultant, i.e., the dimensions is obtained from the position of the resultant. The main part of this research is to present the differences between the two models. Results show that the trapezoidal combined footing is more economical compared to the rectangular combined footing. Therefore, the new model for the design of trapezoidal combined footings should be used, and complies with real conditions.

• Earthquakes and Structures
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• v.5 no.3
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• pp.297-319
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• 2013

Two destructive earthquakes occurred on October 23 and November 9, 2011 in Van province of Turkey. The damage in residential units shows significant deviation from the expectation of decreasing damage with increasing distance to epicenter. The most damaged settlement Ercis has the same distance to the epicenter with Muradiye, where no damage occurred while relatively less damage observed in Van having half distance. These three cities seem to have resembling soil conditions. If the damages are evaluated: joint failures and insufficient lap splice lengths are observed to be the main causes of the total collapses in RC buildings. Additionally, low concrete strength, reinforcement detailing mistakes, soft story, heavy overhang, pounding and short columns are among other damage reasons. Examples of damages due to non-structural elements are also given. Remarkable points about seismic damages are: collapsed buildings with shear-walls, heavily damaged buildings despite adequate concrete strength due to detailing mistakes, undamaged two-story adobe buildings close to totally collapsed RC ones and undamaged structural system in buildings with heavily damaged non-structural elements. On the contrary of the common belief that buildings with shear-walls are immune to total collapse among civil engineers, collapse of Gedikbulak primary school is a noteworthy example.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.821-845
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• 2016

Extensive researches on distribution of earthquake induced damages in different regions have shown that geological and geotechnical conditions of the local soils significantly influence behavior of alluvial areas under seismic loading. In this article, the site of Babol city which is formed up of saturated fine alluvial soils is considered as a case study. In order to reduce the uncertainties associated with earthquake resistant design of structures in this area (Babol city), the required design parameters have been evaluated with consideration of site's dynamic effects. The utilized methodology combines experimental ground ambient noise analysis, expressed in terms of horizontal to vertical (H/V) spectral ratio, with numerical one-dimensional response analysis of soil columns using DEEPSOIL software. The H/V spectral analysis was performed at 60 points, experimentally, for the region in order to estimate both the fundamental period and its corresponding amplification for the ground vibration. The investigation resulted in amplification ratios that were greater than one in all areas. A good agreement between the proposed ranges of natural periods and alluvial amplification ratios obtained through the analytical model and the experimental microtremor studies verifies the analytical model to provide a good engineering reflection of the subterraneous alluviums.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.637-649
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• 2021

Great efforts have been conducted to investigate the seismic performances of the arch and rectangular underground structures, however, the differences between seismic responses of these two types of underground structures, especially the vault radian influencing the seismic responses of arch structures are not clarified. This paper presents a detailed numerical investigation on the seismic responses of arch underground structures with different vault radians, and aims to illustrate the rule that vault radian affects the seismic responses of underground structures. Five arch underground structures are built for nonlinear soil-structure interaction analysis. The internal forces of the structural components of the underground structures only under gravity are discussed detailedly, and an optimum vault radian for perfect load-carrying functionality of arch underground structures is suggested. Then the structures are analyzed under seven scaled ground motions, amounting to a total of 35 dynamic calculations. The numerical results show that the vault radian can have beneficial effects on the seismic response of the arch structure, compared to the rectangular underground structures, causing the central columns to suffer smaller axial force and horizontal deformation. The conclusions provide some directive suggestions for the seismic design of the arch underground structures.

• Earthquakes and Structures
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• v.21 no.6
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• pp.627-639
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• 2021

Fragility curves are being more significant as a useful tool for evaluating the relationship between the earthquake intensity measure and the effects of the engineering demand parameter on the buildings. In this paper, the effect of different site conditions on the vulnerability of the structures was examined through the fragility curves taking into account different strength capacities of the precast columns. Thus, typical existing single-story precast RC industrial buildings which were built in Turkey after the year 2000 were examined. The fragility curves for the three typical existing industrial structures were derived from an analytical approach by performing non-linear dynamic analyses considering three different soil conditions. The Park and Ang damage index was used in order to determine the damage level of the members. The spectral acceleration (Sa) was used as the ground motion parameter in the fragility curves. The results indicate that the fragility curves were derived for the structures vary depending on the site conditions. The damage probability of exceedance values increased from stiff site to soft site for any Sa value. This difference increases in long period in examined buildings. In addition, earthquake demand values were calculated by considering the buildings and site conditions, and the effect of the site class on the building damage was evaluated by considering the Mean Damage Ratio parameter (MDR). Achieving fragility curves and MDR curves as a function of spectral acceleration enables a quick and practical risk assessment in existing buildings.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.1
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• pp.1377-1387
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• 1968

In order to measure runoff and soil losses produced in a small test plot during rainfall, it is usually insufficient to use a tank only, necessitating the combined use of a main tank and a subsidiary tank. Accordingly. exact measurement largely depends on how to connect those two measuring tanks. The main purpose of this thesis is to improve the connecting parts of two measuring tanks so as to assure exact measurement of runoff and soil losses. In this experiment, two types of main tank, i. e. A-type and B-type, were used. A-type is a square tank having a flume at its end. At the flume, ten apertures are provided by using metal columns so as to be able to catch one tenth of total muddy flow discharging at the end of the flume, One tenth of total flow is led to the subsidiary tank through a slot sampler fixed to an aperture. B-type differes in that its flume does not have apertures and slot sampler is fixed directly to the end of the flume, other features being the same as those of A-type. Discharge volumes were measured by using weighing tanks and compared. The effect of baffle screen provided in the flume was also observed in connection with exact measurements. In order to keep main tank and its flume in a horizontal position, bolts and nuts mechanism was used. Vertical and horizontal screens were provided in the main to prevent coarse sands coming into the flume. The conclusion derived through this experiment is as follows: (1) The discharge through slot sampler at each aperture is almost the same for A-type. However, it is slightly more than one tenth of total discharge volume. (2) In case that baffle screen is provided in the flume of A-type tank, the discharge volume of slot sampler is less than that of the same type without screen. (3) For B-type tank, slot sampler discharge increases as slot sampler nears toward the center of flume. (4) When baffle screen is provided in the flume of B-type, slot sampler discharge is less than that of the same type without screen, and this phenomenon is more apparent as compared with A-type. (5) In case that the slot width of slot sampler for B-type is one inch, slot sampler discharge exceeds one tenth of total discharge volume. (6) When the slot width for B-type is 15/16 inch and slot sampler is fixed 3/8 inch apart from either flume wall, slot sampler discharge is approximately equal to one tenth of total discharge volume.

• Journal of Forest and Environmental Science
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• v.17 no.1
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• pp.104-115
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• 2001

This study was carried out to to execute the slope stabilization scheme of soil and weathered rock slope with forest road generating slope failure due to heavy rainfall. The timber piled stabilization by Shin's formulae for landslide-restraint pile as elastically supported elastic columns under distributed loads was applied on the unstable fill slope. The results obtained were summarized as follows: The timber piled stabilization was applied for unstable slopes such as the soil slope and weathered rock slope of metamorphic rock regions. The results indicated that pile interval of 0.5~1.0m was appropriate in the case of high hillslope gradients and 0.7~2.0m in the case of low hillslope gradients of soil slope, and Pile interval of 0.5~1.3m in the case of high hillslope gradients and 0.7~2.0m in the case of low hillslope gradients of weathered rock slope. Recommended pile length was around 4m for pile 1, 2 and 3, and nearly 3m for pile 4 and 5.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.445-455
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• 2009

Microbiological sulfate reduction is the transformation of sulfate to sulfide catalyzed by the activity of sulfate-reducing bacteria using sulfate as an electron acceptor. Low solubility of metal sulfides leads to precipitation of the sulfides in solution. The effects of microbiological sulfate reduction on in-situ precipitation of arsenic and copper were investigated for the heavy metal-contaminated soil around the Songcheon Au-Ag mine site. Total concentrations of As, Cu, and Pb were 1,311 mg/kg, 146 mg/kg, and 294 mg/kg, respectively, after aqua regia digestion. In batch-type experiments, indigenous sulfate-reducing bacteria rapidly decreased sulfate concentration and redox potential and led to substantial removal of dissolved As and Cu from solution. Optimal concentrations of carbon source and sulfate for effective microbial sulfate reduction were 0.2~0.5% (w/v) and 100~200 mg/L, respectively. More than 98% of injected As and Cu were removed in the effluents from both microbial and chemical columns designed for metal sulfides to be precipitated. However, after the injection of oxygen-rich solution, the microbial column showed the enhanced long-term stability of in-situ precipitated metals when compared with the chemical column which showed immediate increase in dissolved As and Cu due to oxidative dissolution of the sulfides. Black precipitates formed in the microbial column during the experiments and were identified as iron sulfide and copper sulfide. Arsenic was observed to be adsorbed on surface of iron sulfide precipitate.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.13-22
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• 2021

Pile or column supported embankments have been increasingly employed to construct highway or railway embankments over soft soils. Piles or columns of stiffer material installed in the soft ground can provide the necessary support by transferring the embankment load to a firm stratum using a soil arching. However, there has been reported to occur a relatively large differential settlement between the piles and the untreated soils. Geosynthetic reinforced pile or column supported embankment (GRPS) is often used to minimize the differential settlement. Two dimensional finite element anlyses have been performed on both the column supported embankments and the geogrid reinforced column supported embankments by using a PLAXIS 2D to evaluate the soil arching effect. Based on the results obtained from finite element analyses, the stress reduction ratio decreases as the area replacement ratio increases in the column supported embankments. For the geogrid reinforced column supported embankments, the geogrid reinforcemnt can reduce differential settlements effectively. In additon, the use of stiffer geogrid is appeared to be more effective in reducing the differential settlements.

• Journal of Microbiology
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• v.41 no.3
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• pp.196-201
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• 2003

The object of this study was to characterize Bacillus strains GB-017 and GB-0356, which produce antifungal substances, especially for plant pathogens. In addition, this study was undertaken to characterize the culture conditions required for the production of antifungal substances and to document some of the properties of the antifungal substance produced by these soil-isolated strains. Strains GB-0365 and GB-017 were found to be bacillus-shaped, gram-positive and motile, and to inhibit Botrytis cineria, Fusarium sp., Pythium sp., and Rhizoctonia solani. Antagonistic activity was maintained up to pH 9.0, and the antifungal activity was stable to heat at 80$^{\circ}C$ for 1 h. Antifungal substances were separated and purified using ion exchange and adsorption columns including WK-I0(H$\^$＋) (pH 7.0), HP20 column (pH 3.0) and IPA (pH 3.0). and IPA. Its UV absorption spectrum showed major peaks at 231 and 259 nm, corresponding to polyene and lactone. A fast atom bombardment mass spectrum (FAB MS) showed a highest peak at 441 m/z and major peaks at 192, 205, and 370 m/z.