As sediments are produced and accumulated in sedimentary basins especially in dams’ reservoirs and they highly affect the reservoirs life span, it is essential to scrutinize the effect of lithology and types of geolo...As sediments are produced and accumulated in sedimentary basins especially in dams’ reservoirs and they highly affect the reservoirs life span, it is essential to scrutinize the effect of lithology and types of geological formations of an area on the life span of reservoirs specifically from the viewpoints of the erodability of these formations due to their lithology type. Lali area, Khuzestan, Iran and the water catchment of the intended area (based on geological situation and Taraz dam situation) are placed in the sedimentary-structural zone of the folded Zagros. The method of this research is based on analyzing the topography and geology maps and field work in order to identify the lithology of the geological formations. In fact, the amount of its erodability has been characterized by the type of the geological formations. The current research aims at putting the geological results, lithological data of the formations types and the outcrop of the soil-lithological units together in order to evaluate the sedimentary and erosive factors of these units and precisely identify the area’s geological formations to remove the ambiguities in this issue. Studies indicate that formations made of looser gypsum and marl like Pabde-Gurpi and Gachsaran are exposed to more sedimentation and erosion than the formations made of compacted lime stone and conglomerate with silica-lime cement such as Bakhtiary and Asmari formations and the sand stones of Aghajari formation reveal the moderate to high resistance. Thus, the lithological identification of the formations, the type of sediments and their looseness and hardness contribute to detect the amount and type of deposits entering into the dam reservoir. The type and amount of these transported and deposited sediments are assessed to predict more suitable optimized ways to exploit dams’ reservoirs.展开更多
Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spect~＇a, even if the diagrams recorded at the site in question. In orde...Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spect~＇a, even if the diagrams recorded at the site in question. In order to design earthquake resistant structures, we, instead, suggest constructing a design spectrum using a set of spectra that have common characteristics to the recorded acceleration diagrams at a particular site and smoothing the associated data. In this study, we conducted a time history analysis and determined a design spectrum for the region near the Lali tunnel in Southwestern Iran. We selected 13 specific ground motion records from the rock site to construct the design spectrum. To process the data, we first applied a base-line correction and then calculated the signal-to-noise ratio （]~SN） for each record. Next, we calculated the Fourier amplitude spectra of the acceleration pertaining to the signal window （1）, and the Fourier amplitude spectra of the associated noise （2）. After dividing each spectra by the square root of the selected window interval, they were divided by each other （1 divided by 2）, in order to obtain the ~SN ratio （filtering was also applied）. In addition, all data were normalized to the peak ground acceleration （PGA）. Next, the normalized vertical and horizontal responses and mean response spectrum （50%） and the mean plus-one standard deviation （84%） were calculated for all the selected ground motion records at 5% damping. Finally, the mean design spectrum and the mean plus-one standard deviation were plotted for the spectrums. The equation of the mean and the above-mean design spectrum at the Lali tunnel site are also provided, along with our observed conclusions.展开更多
Seismic control of cable-stayed bridges is of paramount importance due to their complex dynamic behavior,high flexibility,and low structural damping.In the present study,several semi-active Fuzzy Control Algorithms(FC...Seismic control of cable-stayed bridges is of paramount importance due to their complex dynamic behavior,high flexibility,and low structural damping.In the present study,several semi-active Fuzzy Control Algorithms(FCAs)for vibration mitigation of Lali Cable-Stayed Bridge are devised.To demonstrate the efficiency of the algorithms,a comprehensive nonlinear 3-D model of the bridge is created using OpenSees.An efficient method for connecting MATLAB and OpenSees is devised for applying FCAs to the structural model of the bridge.Two innovative fuzzy rulebases are introduced.A total of six different fiuzzy rule-bases are utilized.The efficiency of the FCAs is evaluated in a comparative manner.The performance of fuzzy control systems is also compared with a sky-hook and a passive-on system.Moreover,the sensitivity of efficiency of control systems to the peak ground acceleration is evaluated qualitatively.In addition,the effect of time lag is also investigated.This study thoroughly examines the efficiency of the FCAs in different aspects.Therefore,the results can be regarded as a general guide to design semi-active fuzzy control systems for vibration mitigation of cable-stayed bridges.展开更多
文摘As sediments are produced and accumulated in sedimentary basins especially in dams’ reservoirs and they highly affect the reservoirs life span, it is essential to scrutinize the effect of lithology and types of geological formations of an area on the life span of reservoirs specifically from the viewpoints of the erodability of these formations due to their lithology type. Lali area, Khuzestan, Iran and the water catchment of the intended area (based on geological situation and Taraz dam situation) are placed in the sedimentary-structural zone of the folded Zagros. The method of this research is based on analyzing the topography and geology maps and field work in order to identify the lithology of the geological formations. In fact, the amount of its erodability has been characterized by the type of the geological formations. The current research aims at putting the geological results, lithological data of the formations types and the outcrop of the soil-lithological units together in order to evaluate the sedimentary and erosive factors of these units and precisely identify the area’s geological formations to remove the ambiguities in this issue. Studies indicate that formations made of looser gypsum and marl like Pabde-Gurpi and Gachsaran are exposed to more sedimentation and erosion than the formations made of compacted lime stone and conglomerate with silica-lime cement such as Bakhtiary and Asmari formations and the sand stones of Aghajari formation reveal the moderate to high resistance. Thus, the lithological identification of the formations, the type of sediments and their looseness and hardness contribute to detect the amount and type of deposits entering into the dam reservoir. The type and amount of these transported and deposited sediments are assessed to predict more suitable optimized ways to exploit dams’ reservoirs.
文摘Most acceleration diagrams show high levels of unpredictability, as a result, it is the best to avoid using diagrams of earthquake acceleration spect~＇a, even if the diagrams recorded at the site in question. In order to design earthquake resistant structures, we, instead, suggest constructing a design spectrum using a set of spectra that have common characteristics to the recorded acceleration diagrams at a particular site and smoothing the associated data. In this study, we conducted a time history analysis and determined a design spectrum for the region near the Lali tunnel in Southwestern Iran. We selected 13 specific ground motion records from the rock site to construct the design spectrum. To process the data, we first applied a base-line correction and then calculated the signal-to-noise ratio （]~SN） for each record. Next, we calculated the Fourier amplitude spectra of the acceleration pertaining to the signal window （1）, and the Fourier amplitude spectra of the associated noise （2）. After dividing each spectra by the square root of the selected window interval, they were divided by each other （1 divided by 2）, in order to obtain the ~SN ratio （filtering was also applied）. In addition, all data were normalized to the peak ground acceleration （PGA）. Next, the normalized vertical and horizontal responses and mean response spectrum （50%） and the mean plus-one standard deviation （84%） were calculated for all the selected ground motion records at 5% damping. Finally, the mean design spectrum and the mean plus-one standard deviation were plotted for the spectrums. The equation of the mean and the above-mean design spectrum at the Lali tunnel site are also provided, along with our observed conclusions.
文摘Seismic control of cable-stayed bridges is of paramount importance due to their complex dynamic behavior,high flexibility,and low structural damping.In the present study,several semi-active Fuzzy Control Algorithms(FCAs)for vibration mitigation of Lali Cable-Stayed Bridge are devised.To demonstrate the efficiency of the algorithms,a comprehensive nonlinear 3-D model of the bridge is created using OpenSees.An efficient method for connecting MATLAB and OpenSees is devised for applying FCAs to the structural model of the bridge.Two innovative fuzzy rulebases are introduced.A total of six different fiuzzy rule-bases are utilized.The efficiency of the FCAs is evaluated in a comparative manner.The performance of fuzzy control systems is also compared with a sky-hook and a passive-on system.Moreover,the sensitivity of efficiency of control systems to the peak ground acceleration is evaluated qualitatively.In addition,the effect of time lag is also investigated.This study thoroughly examines the efficiency of the FCAs in different aspects.Therefore,the results can be regarded as a general guide to design semi-active fuzzy control systems for vibration mitigation of cable-stayed bridges.
