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131.
Unreinforced masonry houses are composed of building blocks with weak inter‐binding action between them which commonly possess low tensile strength. The principal tensile stresses generated by out‐of‐plane bending and in‐plane shear forces cannot be tolerated well and leads to heavy structural damage and brittle collapse beyond linear capacity of the material. Remedies such as externally applied mesh reinforcement and post‐tensioning improves post and pre‐cracking performances; however, yielding of reinforcement material or shortening of walls due to cracking causes loss of integrity and post‐tensioning force. This paper discusses a research programme on earthquake strengthening of masonry houses using post‐tensioning by elastomeric straps and related shaking table tests on 1/10 scale single storey rural dwelling models. The aim of the study is to assess the use and effectiveness of post‐tensioning rubber straps at several different configurations especially for houses with heavy earth roofs supported on wooden logs. Full‐scale application can be conducted using scrap automobile tyres, which might be implemented as an economic and environment friendly alternative strengthening technique for poor residents of low‐cost dwellings. The performance and validity of the proposed strengthening techniques were tested on 1/10 scale models using a simplistic shaking table. The structural performance of the reinforced models with vertical post‐tensioning rubber straps was significantly improved as compared to the original specimen; the results were even better when vertical and horizontal straps were used. Obtained results show promise for seismic strengthening using rubber straps for post‐tensioning. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
132.
Sinan Akkar Özkan Kale Ahmet Yakut Ulubey Çeken 《Bulletin of Earthquake Engineering》2018,16(8):3439-3463
This study describes the methodology implemented to establish the ground-motion logic-tree for national probabilistic seismic hazard map of Turkey for shallow active crustal regions. The presented procedure provides quantitative information to guide the hazard experts while establishing the logic tree to capture the epistemic uncertainty in ground-motion characterization. It uses non-data-driven and data-driven testing methods to identify and rank candidate ground-motion prediction equations (GMPEs) under a specific ground-motion database. The candidate GMPEs are subjected to visual inspection and are classified into center, body and range (CBR) spectral estimates for a proper consideration of epistemic uncertainty. The GMPEs classified into CBR are then used in a suite of seismic hazard sensitivity analysis to establish the most suitable GMPE logic-tree whose spectral estimates are not biased by any one of the GMPEs in the logic-tree structure. The sensitivity analysis considers normalized spectral ordinates and is not manipulated by the spectral amplitudes. The proposed procedure is inherited from the relevant studies of the Earthquake Model of the Middle East (EMME; www.efehr.org:8080/jetspeed/portal/emme.psml) regional seismic hazard project. This paper also highlights the similarities and differences in ground-motion characterization between EMME and our approach. 相似文献
133.
The physical process of oxygen transfer or oxygen absorption from the atmosphere acts to replenish the used oxygen, a process termed re‐aeration or aeration. Aeration enhancement by macro‐roughness is well‐known in water treatment and one form is the aeration cascade. The macro‐roughness of the steps significantly reduces the flow velocities and leads to flow aeration along the stepped cascade. In this paper, the aeration efficiency in stepped cascade aerators was modeled by using the Adaptive Network Based Fuzzy Inference System (ANFIS). The obtained model was tested with experimental data. Test results showed that ANFIS can be used to estimate the aeration efficiency in stepped cascade aerators. 相似文献
134.
R.C. Rodrguez Martn-Doimeadios E. Tessier D. Amouroux R. Guyoneaud R. Duran P. Caumette O.F.X. Donard 《Marine Chemistry》2004,90(1-4):107
Species-specific enriched stable isotopes have been used to study mercury transformations (methylation, demethylation and volatilization) in estuarine sediments under different environmental conditions (both biotic and abiotic and oxic and anoxic). These experiments have demonstrated the potential for the isotopically enriched species in combination with highly sensitive measurement methods (ICP MS) to facilitate the study of mercury speciation and reactivity. Sediments (sterilized and nonsterilized) were spiked with both isotopically enriched inorganic (199Hg) and monomethylmercury (MM201Hg) at environmental levels to avoid perturbing the system and incubated under both aerobic and anaerobic conditions. The formation of MM199Hg and the degradation of MM201Hg were measured simultaneously during time series experiments by capillary gas chromatography-inductively coupled mass spectrometry. Specific methylation and demethylation rate constants (Km and Kd) were calculated. Results clearly showed that methylmercury levels in sediments are controlled by competing and simultaneous methylation and demethylation reactions. Operating conditions, likely to drastically modify the reactivity of the media, were of primary importance to assess the relative significance of each mechanism. In estuarine sediments, mercury methylation was enhanced under anaerobic nonsterile conditions, whereas other environmental conditions were either less favorable for monomethylmercury production or more effective for its degradation. The production of total gaseous mercury was found to be minimal, although it could be demonstrated that it was related to the fate and transformation of methylmercury. 相似文献
135.
Volkan Bakis Ahmet Erdem Edwin Budding Osman Demircan Hicran Bakis 《Astrophysics and Space Science》2005,296(1-4):131-134
An astrometric solution, together with time of minimum analysis, has been made for the multiple system XY Leonis (HIP 49136)
to identify the properties of the remote companion to the eclipsing pair (AB). From this solution, we derive the inclination
of the wide orbit (AB-cd) as 94.4∘± 0.2∘, angle of nodes as 247.3∘± 0.2∘, and the mass of the wide component (the dwarf binary cd) as 0.98 ± 0.2 M⊙. This study confirms that the light travel time effect can explain the sinusoidal O−C variation of the eclipsing system. 相似文献
136.
G. Handler M. Jerzykiewicz E. Rodríguez K. Uytterhoeven P. J. Amado T. N. Dorokhova N. I. Dorokhov E. Poretti J.-P. Sareyan L. Parrao D. Lorenz D. Zsuffa R. Drummond J. Daszyska-Daszkiewicz T. Verhoelst J. De Ridder B. Acke P.-O. Bourge A. I. Movchan R. Garrido M. Paparó T. Sahin V. Antoci S. N. Udovichenko K. Csorba R. Crowe B. Berkey S. Stewart D. Terry D. E. Mkrtichian C. Aerts 《Monthly notices of the Royal Astronomical Society》2006,365(1):327-338
137.
Vertical and horizontal variations of the frequency of crustal earthquakes (h ≤ 35 km) that have occurred in and around Turkey
are analyzed, using data from the Global Hypocenter Data Base and the IRIS data for the period 1964–1998. Fits of various
magnitude scales to the observations have been used to construct a homogeneous catalogue. Depth distribution of the parameters
derived from the Gutenberg–Richter relationship reveals that there is a depth dependence in the a- and b-values of the frequency
distribution. It is observed that unknown focal depths (0, 10, 33 km) are dominant in the total seismicity reported, and give
rise to substantial changes to the vertical distribution of these parameters. It is also observed that the parameters of either
a or b alone may not be used as a measure of regional seismicity of the study area in which high and low seismic activity
observed over short distances. In contrast, distribution of modal (a/b) values provides detailed images of the local areas
presented by high and low seismic zones. This study presents evidence that low b-values are associated with major strike-slip
faults, particularly exhibiting high apparent stresses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
138.
139.
In landslide susceptibility mapping, factor weights have been usually determined by expert judgements. A novel methodology for weighting landslide causative factors by integrating statistical feature weighting algorithms was proposed. The primary focus of this study is to investigate the effectiveness of automatic feature weighting algorithms, namely Fisher, Chi-square and Relief-F algorithms. Analytic hierarchy process (AHP) method was used as a benchmark method to compare the performances of the weighting algorithms. All weighted factors were tested using factor-weighted overlay method, and quality of these maps was assessed using overall accuracy, area under the ROC curve (AUC) and success rate curve. In addition, Wilcoxon’s signed-rank test was applied to evaluate statistical differences between both estimated overall accuracies and AUCs, respectively. Results showed that the weights determined by feature weighting methods outperformed the conventional AHP method by about 6% and this level of differences was found to be statistically significant. 相似文献
140.
A short cut numerical method for evaluation of the modes of free oscillations of the basins which have irregular geometry and bathymetry is presented in this paper. In the method, a single wave is inputted to the basin as an initial impulse. The respective agitation in the basin is computed by using the numerical method solving the nonlinear form of long wave equations. The time histories of water surface fluctuations at different locations due to propagation of the waves in relation to the initial impulse are stored and analyzed by the fast Fourier transform technique (FFT) and energy spectrum curves for each location are obtained. The frequencies of each mode of free oscillations are determined from the peaks of the spectrum curves. The method is tested by using regular shaped flat bottom basins with different depths. The computed periods of free oscillations are compared with the theoretical values. The accuracy and performance of the method are discussed. As a case study for the application to the basins of irregular shape and bathymetry, the periods of free oscillations of the sea of Marmara is determined and discussed. 相似文献