An experimental study on steel‐encased buckling‐restrained brace hysteretic dampers

This paper describes a seismic test program performed on 12 steel‐encased buckling‐restrained braces (BRBs). The use of rolled or built‐up buckling‐restraining mechanisms with welded or bolted attachments was examined. In addition, the effects of bolt pretension, core‐to‐encasing attachment details, aspect ratio of core segment and imperfections due to manufacturing on the brace response were investigated. All specimens were subjected to a stepwise incremental quasi‐static testing protocol with a maximum axial strain amplitude of 2%. All specimens except one showed satisfactory performance with stable hysteretic response and sustained cumulative inelastic deformations in excess of 200 times the yield deformation. Based on the experimental results, the compression strength adjustment factor, and the strain hardening adjustment factor for each excursion were quantified. Test results revealed that these two factors are significantly influenced by the parameters investigated in the experimental program. BRB details were also found to influence the buckling and the yielding patterns of the core segment. Copyright © 2009 John Wiley & Sons, Ltd.     

Earthquake imprints on a lacustrine deltaic system: The Kürk Delta along the East Anatolian Fault (Turkey)

Deltas contain sedimentary records that are not only indicative of water‐level changes, but also particularly sensitive to earthquake shaking typically resulting in soft‐sediment‐deformation structures. The Kürk lacustrine delta lies at the south‐western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re‐evaluates water‐level changes and earthquake shaking that have affected the Kürk Delta, combining geophysical data (seismic‐reflection profiles and side‐scan sonar), remote sensing images, historical data, onland outcrops and offshore coring. The history of water‐level changes provides a temporal framework for the depositional record. In addition to the common soft‐sediment deformation documented previously, onland outcrops reveal a record of deformation (fracturing, tilt and clastic dykes) linked to large earthquake‐induced liquefactions and lateral spreading. The recurrent liquefaction structures can be used to obtain a palaeoseismological record. Five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the East Anatolian Fault. Sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator. Based on radionuclide dating (¹³⁷Cs and ²¹⁰Pb), two major sedimentary events were attributed to the ad 1874 to 1875 East Anatolian Fault earthquake sequence. Their sedimentological characteristics were determined by X‐ray imagery, X‐ray diffraction, loss‐on‐ignition, grain‐size distribution and geophysical measurements. The events are interpreted to be hyperpycnal deposits linked to post‐seismic sediment reworking of earthquake‐triggered landslides.     

A literature review of Algerian salt lakes: values,threats and implications

Chotts are salt lakes located in the arid regions of Northern Africa. These unique wetlands are recognized for their role in the migration and breeding of waterbirds and economic values generated from mineral extraction, agriculture and tourist activities. Despite their importance for flora and fauna biodiversity, they continue to face important threats due to human activities. This article consolidates a literature review of Algerian chotts from global to local importance. An in-depth view demonstrates the changes in land use of two large chotts in the southeastern region of Algeria: Chotts Merouane and Melghir. Land use images highlight a net expansion of agricultural lands, a decrease in grazing area around the lakes and a decrease of salt lake surface area. The local focus highlights the threats and changes of Algerian and Northern African chotts and proposes some perspectives for the future.     

Investigation of zinc extraction from different leach residues by acid leaching

With different properties, zinc is one of the most important non-ferrous metals and it is used in various application areas, especially as an anti-corrosion agent. In Turkey, zinc production was based on zinc carbonate ores (ZnCO₃), at Çinkur plant from establishment to 1997 due to high reserves of zinc carbonate. After that, zinc concentrate coming from Iran was used in this plant over the last two decades. Thus, two different leach residues called as Turkish leach residue (TLR) and Iranian leach residue (ILR) were accumulated more than one million ton in Çinkur stock piles. In this study, it is aimed to investigate zinc recovery for each leach residue by use of sulphuric acid (H₂SO₄) and to compare the TLR and the ILR. Initially, detailed chemical, mineralogical and thermal analyses of these different leach residues were carried out. In order to investigate the effect of acid concentration and reaction duration on zinc recovery, leaching experiments were carried out at following conditions: 95 °C, 100 g/L pulp density and 600 rpm stirring rate. According to the characterization results, the chemical compositions for both residues are nearly similar; however, experimental results show that zinc recovery per cent of the ILR was higher than that of TLR for all experimental durations and acid concentrations. This may be due to the presence of Zn-containing compounds in the both residues at different percentages.     

Daily suspended sediment estimation using neuro-wavelet models

This paper proposes the application of neuro-wavelet technique for modeling daily suspended sediment–discharge relationship. The neuro-wavelet models are obtained by combining two methods, artificial neural networks (ANN) and discrete wavelet transform. The accuracy of the neuro-wavelet and the ANN models is compared with each other in suspended sediment load estimation. The daily streamflow and suspended sediment data from two stations on Tongue River in Montana are used as case studies. The comparison results reveal that the suggested model could increase the estimation accuracy.     

October 23, 2011 Turkey/Van–Ercis earthquake: structural damages in the residential buildings

On October 23, 2011, a magnitude of Mw 7.2 earthquake struck the Van province in eastern Turkey which caused approximately 600 life loss and 4,000 injured people. Although the recorded peak ground accelerations were relatively low (0.15–0.2 g) compared with that of other recent destructive Turkish earthquakes and the code-based design response spectrum, a large number of reinforced concrete buildings with 4–6 stories and non-engineered masonry buildings were either heavily damaged or collapsed in the region. Based on the post-earthquake technical inspections, the goal of this paper is to introduce major reasons for structural damages in the disaster area and to discuss these failures along with the approaches given in the design code which is renewed after August 17, 1999 Marmara Earthquake. Some remarkable lessons learned from earthquake-induced failures and damages specific to building construction techniques are presented in this paper.     

Use of Pistachio Shells as an Adsorbent for the Removal of Zinc(II) Ion

In this study, the removal of zinc(II) ion from an aqueous solution by pistachio shells (PS) is investigated. The dynamic behavior of the adsorption is examined on the effects of pH, adsorbent dosage, and contact time. The adsorption rates are determined quantitatively and simulated by the Lagergren first order, pseudo‐second order, Elovich, and intra‐particle diffusion kinetic models. The adsorption kinetic models are also tested for validity. The thermodynamic parameters, which are also deduced from adsorption experiments, are very useful in elucidating the nature of adsorption. The experimental results reveal that the optimum pH value and the contact time for the adsorption of Zn²⁺ onto PS are found as 6 and 10 min, respectively. According to these parameters, adsorption process follows the pseudo‐second order kinetic model with high correlation coefficients (R² = 0.999). The obtained results demonstrate that PS is a reasonably effective adsorbent for the removal of Zn²⁺ from aqueous leachate of hazardous waste.     

Ecological risk assessment using trace elements from surface sediments of Izmit Bay (Northeastern Marmara Sea) Turkey

The aim of this study was to study ecological risk assessment of trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in Izmit Bay surface sediments in the <63 microm fraction. Sediment samples were collected from 8 sites along the north coastline of the bay. Samples were subjected to a total digestion technique and analyzed for major (organic carbon) and minor (As, Cd, Cr, Cu, Ni, Pb and Zn) elements. Sediments heavily contaminated are evaluated by the Sediment Quality Guidelines (SQG) of US EPA. The degree of contamination (Cd) is estimated as very high at each site. Two sets of SQGs, effect range-low/effect range median values and TEL/probable effect level (PEL) values were used in our study. Sediments from the each site are judged toxic when two or more of the PEL values exceed EPA guidelines. Our results are in agreement with previously reported sediment toxicity test results.