Behaviour of steel cushions subjected to combined actions

Mild steel is relatively low-cost and easily accessible material to fabricate some structural members. It would be a significant advantage if seismic energy dissipaters that are used in structures constructed in the earthquake prone areas, could also be produced on site. In this paper, a promising seismic energy dissipater made of mild steel, so-called steel cushion (SC) is presented. It is provided experimental and analytical responses of SCs subjected to bi-axial loadings. SC rolls under the lateral loading that allows relocation of the plasticized cross-section. Henceforth, SC dissipates considerable amount of seismic energy. A series of tests were performed to achieve experimentally the behavior of SC subjected to longitudinal and transversal loading. Finite Element Models (FEMs) were also generated to reproduce the experimental backbone curves and to predict the bi-directional response properties for discrete transversal forces and plate thicknesses. Closed-form equations were derived to determine yield and ultimate forces and the corresponding displacements as well as location of the plasticized sections. The behavior of SC could either be projected by the FEMs with the exhibited parameters or by means of the proposed closed-form equations and the normalized design chart.     

Comparison of TRMM-based flood indices for Gaziantep,Turkey

Floods are the most common natural disasters threatening the welfare of humanity. Gaziantep, a city located in a semi-arid region of Turkey, is occasionally flooded, and in May 2014, a flood not only caused property damage, but also resulted in the death of a lady who became trapped in flood waters. The fatality and property damage of flash floods arise from the limited response time for remediation. Despite improvements in numerical weather predictions, forecasting flash floods is not easy. Due to its frequent observations, Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) real-time (RT) 3B42RT data are tested for Gaziantep flood predictions in this study. During TRMM era, six floods occurred in Gaziantep. Three-hourly 3B42RT data covering the 2000- to 2014-year period indicated high rain rates during months in which floods were observed. Also daily variation of rainfall was well represented. High-intensity rain (HIR), cumulative distribution functions (CDF) and Gaziantep Flood Index (GAFI) indices are developed for flood characterization. HIR, calculated as 10 mm/h, detected October and December of 2010 floods. CDFs with 99, 98.5, 95 and 91.3% indicated 4 floods occurred in August 2005, June 2007, October 2010 and December 2010, respectively. GAFI was able to detect 4 out of 6 occurrences (August 2005, June 2007, October 2010 and December 2010) as values ranging from 1 to 2.63 are selected for monthly precipitation. In the missed occurrence, 3B42RT did not indicate any rainfall. Although only rain rates are used in flood characterization, the results are promising, and the simplicity of the methodology favors its usage. Also, methodology can easily be implemented to TRMM following missions such as Global Precipitation Measurement Mission.     

The accumulation of silver and gold in Lemna gibba L. exposed to secondary effluents

Aquatic plants are used as a practical and effective method to remove toxic metals from secondary-treated municipal wastewater. In this study, Lemna gibba was investigated for its capacity to remove silver (Ag) and gold (Au) from secondary effluents. L. gibba was collected from a natural lake and then acclimatized to the effluent in situ. The concentration of toxic elements in the plant material was monitored as a function of time over 7 days. L. gibba accumulated significant amounts of Ag and Au for six days from initiation of the experimental study. The highest accumulations were 2303% for Ag and 247% for Au. However, after six days, the rate of Ag and Au accumulation in L. gibba declined, as saturation levels had been reached in the plant tissues. The metal accumulating property of L. gibba can also be commercially exploited to recover Au and Ag from wastewater and mining wastes.     

Local indications of climate changes in Turkey: Bursa as a case example

This study aims to put out on what ratio Bursa province, one of the important heavy industry regions of Turkey, has been affected climatic process called “Global Warming” or “Climate Change”. For this intend climatic measurement results from Bursa center, top of Uludağ Mount, Yenişehir and Keles meteorological stations were used. These measurements were taken as minimum temperature at night-time, maximum temperature at day-time, and mean temperature, mean pressure, insolation intensity, insolation duration, mean wind speed, minimum temperature above soil, soil temperatures at depths of 5, 10, and 20 cm rainfall. Overall, our statistical results showed that there was a considerable warming at statistically 1% and 5% levels in summer months, particularly in July Almost all performed measurements confirm this result. According to climatic data for thirty years (1975–2005), in the last twelve years contrary to previous 18 years, mean temperature values were higher than long-term mean value nine times (years) repetitively. Temperatures did not deviated higher than 0.5°C in six of these. At the temperatures below mean, The maximum deviation was −0.4°C.     

Geological, mineralogical and geochemical characteristics of zeolite deposits associated with borates in the Bigadiç, Emet and Kirka Neogene lacustrine basins, western Turkey

The Bigadiç, Emet and Kirka lacustrine basins of western Turkey may be considered as Tibet-type graben structures that were developed during the Miocene within the Izmir-Ankara suture zone complex. The volcanic-sedimentary successions of these basins are made up of mudstone, carbonate (limestone and dolomite) and detrital rocks, and also of crystal or vitric tuffs about 135 to 200 m thick. The Degirmenli (Bigadiç), Emirler (Bigadiç) Köpenez (Emet) and Karaören (Kirka) tuffs constituting the zeolite deposits are situated beneath four borate deposits (colemanite, ulexite, borax). The most abundant diagenetic silicate minerals are K- and Ca-clinoptilolites in the zeolite deposits, and Li-rich trioctahedral smectites (stevensite, saponite and hectorite) and K-feldspar in the borate deposits. In the Degirmenli, Emirler. Köpenez and Karaören deposits, the following diagenetic faciès were developed from rhyolitic glasses rich in K and poor in Na: (glass + smectite), (K-clinoptilolite + opal-CT), (Caclinoptilolite + K-feldspar ± analcime ± quartz) and (K-feldspar+analcime+quartz). K-feldspar which is also rarely associated with phillipsite (Karaören) and heulandite (Degirmenli and Karaören), succeeds clinoptilolite and precedes analcime in these diagenetic facies where dioctahedral smectites, opal-CT and quartz are the latest minerals. No diagenetic transformations exist between clinoptilolite, K-feldspar and analcime that were formed directly from glass. The lateral facies distributions resulted from the differences in salinity and pH of pore water trapped during deposition of the tuffs, but vertical distributions in vitric tuffs seem to have been controlled by the glass/liquid ratio of the reacting system and the permeability or diffusion rate of alkali elements. The Bigadiç, Emet and Kirka zeolite deposits which were formed in saline basins rich in Ca and Mg ions, show similar chemical changes, i.e. loss of alkalis and gain in alkaline-earth elements that have taken place during the diagenetic transformation of rhyolitic glasses to dioctahedral smectites or clinoptilolite. The absence of sodic zeolites such as mordenite, erionite, chabazite and silica-rich phillipsite is mainly due to the very high K/Na ratio of the starting materials rather than initial alkaline conditions or high Na content in lake waters.