Year:2022 | Volume:52 | Issue:1 (106)|Papers Count:19

1. Introduction: Land subsidence can be counted as a vital concern for human beings due to its harmful effects. The impacts of land subsidence can be seen in several forms, such as cracks in buildings, damage of infrastructures (roads and bridges), tilting and damaged houses, and increases in flooding inundation areas (Gumilar et al., 2015). Overusing of water and soil resources, which can threaten nature and human life, is considered as one of the main reasons for some natural hazards like land subsidence. . .

1. Introduction: In the present paper, the reliability of tubular members used in the horizontal braces of an offshore jacket structure against the failure induced by the presence of stresses higher than the allowable values is evaluated. In order to define the failure criteria, equations proposed by the 21 th edition of API RP 2A-WSD (2007) for the design of tubular members under the combined axial pressure and bending are used. In this study, internal forces of the tubular members and the parameters involved in the member strength are considered as random variables and the probability distribution functions governing these forces including the axial compressive force and in-plane and out-of-plane bending moments are derived for a typical jacket-type platform installed in the Persian Gulf. For the modeling of environmental loads, information available on the sea states in the South Pars region has been used and the results of three different methods of reliability analysis including MVFOSM, HL-RF, and MCS are compared. Finally, based on the results of reliability analysis, a set of equations are proposed for the determination of suitable safety factors for designing the tubular members in horizontal braces of a jacket structure as a function of target reliability index and target failure probability. . .

1. Introduction: Concrete elements can be easily cracked due to several reasons, such as tensile stresses. When these cracks are connected to each other, permeability will increase and bearing capacity will decrease. Therefore, cracks may decrease the durability of concrete structures. Repair of cracked concrete structures is often expensive and sometimes impossible. Therefore, researchers by inspiration from autogenous recovery of small scratches in the body of live creatures, have presented self-healing concrete based on concrete characteristics. Utilization of such concretes may increase the durability of concrete structures and minimize repair and rehabilitation costs. Self-healing phenomenon is not new,Academy of science in France has observed the healing of micro cracks in 1836 (Hearn, N, Morley, 1997). The self-healing refers to the reduction of crack width itself. Systematic investigation of self-healing was started by Glanville in 1926. Autogenous self-healing is a case of healing that happens without using external agents (Glanville, 1931). Cementitious materials have such ability, because rehydration of cement particles may be continued and reaction products such as C-S-H and Portlandite will fill the cracks. Of course, when the unhydrated cement particles and water are available in the cement paste, this type of self-healing will occur. Parameters such as crack width, pH of curing water, temperature, the chemical composition of cement and etc. may influence on the self-healing process...

1. Introduction: According to ASCE 7 (2016), Progressive collapse is described as the distribution of an initial local failure from element to element, resulting finally in the collapse of an entire structure or an extremely large part of it. Now, it has become evident that abnormal loads need to be considered in the design of structures to prevent progressive collapse. Building collapse such as Ronan Point, Alfred P. Murrah, and World Trade Center have shown the catastrophic nature of the progressive collapse, and with an increasing trend towards more terrorist action in the future, it is clear that structural design must include progressive collapse (Starossek, 2018). . .

1. Introduction: Given that advances have been made toward the use of carbon-free or low-carbon energy sources in the modern sciences (Simpson and Tatsuoka, 2008), the development and optimization of more environmentallyfriendly methods are required. Biological practices have their own sensitivity due to their dealings with living organisms. The feasibility of the use of the calcium carbonate precipitation method in the sandy soils contaminated with hydrocarbon pollutants and the use of bacterial flocculation have been recently investigated (Cheng and Shahin, 2017). The purpose of the present research is to investigate the variation of geotechnical parameters of sandy soils contaminated with motor oil. . .

1. Introduction: Nowadays, considering the scarcity of water resources and the increasing growth of population and water demand, Water resource management be deemed to be essential. One way for managerial to deal with the crisis of water scarcity and protect existing water resources, is the management of the Demand and water use in the urban sector. Iran, with an average annual rainfall of 250 mm, is one of the dry countries in the world. The rapid growth of the population over the past few decades and the lack of attention to its control over the country's planning priorities and the inappropriate pattern of energy and water consumption have faced Iran with serious challenges in this regard. Considering the significant reduction in water resources available on a global scale and the importance of achieving sustainable development goals, the study of factors affecting water resource management has been considered more than ever. In order to compare the country's situation in the region, comprehensive information is needed on the amount of per capita consumption and the minimum amount of water needed to achieve a human development pattern. So far in Iran, a study has not been conducted to establish a systemic relationship between the parameters affecting the consumption pattern in the urban sector and modeling the interaction between the pattern of consumption and per capita water as well as the sources of urban water supply using a dynamic system approach. . .

1. Introduction: The faulting phenomenon involves different variables. Some of these variables are determined more accurately than others using non-modeling approaches. The main subject of this paper is to investigate the influence of both individual geometrical and physical input parameters involved in the Earth surface displacement models. For different physical and geometrical parameters, it is recommended to use sensitivity analysis on parameters that are determined from a field study with less accuracy. Both slip rate and locking depth of the fault are major parameters, in this aspect. In this paper, the role of all faulting parameters on surface displacement data has been investigated. To do this analysis, the elastic half-space model of Okada (1985) was used. As a case study, the surface displacements model was applied to the North Tabriz Fault. The medium is composed of an elastic half-space. Sensitivity analysis was conducted on all geometrical and physical parameters. Finally, the regions of the most appropriate surface displacements were determined to obtain the most accurate values for the studied parameters. According to the obtained results, the model parameters, i. e., locking depth and slip rate, could be determined more effectively in the regions near and away from the fault trace, respectively. . .

1. Introduction: Pile capacity estimation by conventional design equations is not so accurate. Besides of uncertainty of geotechnical parameters and the defect of design equations, during pile installation, the soil is highly disturbed. In pile foundation projects, it is necessary to confirm pile capacity by in-situ tests. Many methods are proposed to perform in-situ such as static pile loading test, pile driving formulas based on penetration and rebound of the pile during driving, and wave equation method. Among these methods, the use of the pile driving formula is the easiest and the most economical method. ( Randolph, 2003,Rosenvinge et al., 2004,Bullock, 2012,Likins, 2012,Rajagopal, 2012,Allin et al., 2015,Shooshpasha et al. 2016,Zhussupbekov, 2016,Salgado, 2017) Hiley formula is the only pile driving formula that uses pile rebound in combination with pile penetration for pile capacity estimation(Hiley, 1930). Static pile loading is the most accurate and also expensive test(Fellenius, 1975). Evaluation of capacity by wave equation method is newer than static loading and Hiley formula and with moderate accuracy and cost. In this research, by numerical simulating of the pile driving and pile loading, the results of the mentioned methods (Hiley formula, Wave equation, pile loading test) will be compared. . .

1. Introduction: In this research, the capability of elastic load patterns, including suggested patterns in prevalent seismic codes, and modified elastic patterns such as the Method of Modal Combinations (MMC) and the Upper-Bound Analysis (UPBA) in estimating the nonlinear demands of steel moment frame are evaluated by pushover method. Afterward the results of pushover analysis compared with the results of Nonlinear Time History Analysis (NTHA) affected by near-fault pulse-type ground motion. This study, not only tried to investigate the ability of load patterns to be used in pushover methods but also obtained different inelastic demands such as absolute displacement story (RD), Inter-story Drift Ratio (IDR), global ductility (μ, g) and story ductility (μ, s). Eventually, the error values of each load pattern were reported. The most important innovation of this research is the analytical study of the ability of various patterns of pushover methods against the values derived from nonlinear time history analysis (affected by near-fault earthquakes) in computing the parameters of the general and interstory deformation (which has been less consideration in previous studies) by applying the effect of higher modes. . .

1. Introduction: Achieving efficient methods to protect the structure against forces such as wind and earthquake is one of the first steps in the design of structures and has led to the provision of structural control systems. Structural control systems include three systems, active control, passive control and semi-active control. (Spencer Jr et al. 2003), (Mulligan et al. 2007). The outrigger system with the viscous damper, was proposed by, (Gamaliel, 2008) and its effect on tall structures was investigated, (O'Neill, 2006) showed that the use of damper and increasing damping in the outrigger system in proportion to increasing the stiffness and dimensions of the structure. (Farzad et al. 2019) has also used ultrasonic algorithms to determine the optimal position of outrigger system in tall steel frames. Experimental and analytical researches also show that the use of outrigger system is effective in reducing the lateral displacement of tall structures. (Tan et al. 2012), (Deng et al. 2014). (Jovanovich, 2011) Used the Fourier series method in Hilbert space to investigate the transverse vibrations of the beam with boundary conditions of linear viscosity. In this paper, the vibrations of the structure and the effect of central core system with the damped arm brace using axial load (due to the mass of the central mass) in the control of lateral displacement due to harmonic loading are investigated. Previous studies have not considered the effect of perimeter columns stiffness and the effect of axial force on frequencies and lateral displacement of the structure, and for solving the partial differential equation governing the problem, the Fourier series method is used to define the differential operator in Hilbert space. . .

1. Introduction: Aromatic hydrocarbons are an important group of environmental pollutants that are produced from different sources such as refineries and petrochemical, pharmaceutical, paint, and plastics industries. These environmental pollutants can be removed by different methods such as evaporation, chemical degradation, biological degradation, and adsorption. Biological methods are preferred selective methods because of their simplicity, utilization of environmental-friendly microorganisms, and production of safe materials such as water and carbon dioxide (Singh et al. 2007). Bioremediation is a process for the conversion of toxic materials into non-toxic and safe ones based on the metabolic activity of microorganisms capable of using organic and petroleum pollutants as carbon and energy sources. It is a useful technology with no environmental disruption (Sungpetch 1998). Streptomyces species, which belong to the category of Actinomycetes, are gram-positive and non-moving strains. Most of them produce spores and produce most of the clinically useful antibiotics of natural origin. These species have a different genus, and some of them can degrade aromatic compounds such as benzene, toluene, and even complex petroleum compounds (Claessen et al., 2006). . .

1. Introduction: Investigating changes in the behavior of rivers is of particular importance in the protection of hydraulic structures and the determination of the boundaries of the river bed, as well as the reduction of possible damages. Dams are among the structures that have the greatest impact on river morphology. Therefore, it is very important to study the morphology of rivers flowing to large dams in planning and ease of strategic decision making on the construction of engineering structures along the river. In recent years, due to the unique characteristics of remote sensing and satellite imagery, many studies have been done to investigate river morphological changes (Baki and Ga, 2012,Fisher, 2016). In this research, the study uses 26 Landsat satellite images to investigate the morphological changes of the Bazoft River between 1985-2015. In this regard, the present study investigates morphological changes of the Basoft River, one of the northern Karun sub-basins, which finally enters the Karun 4 dam. In this study, using 26 satellite images of Landsat ETM + and OLI, the displacement pattern of the main river channel, along with the variations in width and sinousity due to sedimentation and erosion processes in long and short periods up to the year 2015 and caused by large floods in this period were investigated. . .

1. Introduction: Shape memory alloy (SMA) is a particular type of metal alloy that has the recovery property of permanent deformation. This alloy includes the typical properties of steel, such as resistance, hardness, performance, and so on. SMAs are used in some applications, including based-isolated buildings, self-repairing building components, aircraft industry, medical industry, mechanical equipment, and effective models for computing tools. In this paper, the effect of SMAs on the cyclic behavior of reinforced concrete (RC) joints is analytically investigated. To this end, after validation of two experimental models in Seismo Struct software, some parametric studies are conducted, such as 1-the effect of compressive strength of concrete, 2-the position of SMA into the plastic zone, 3-the simultaneous use of SMA as longitudinal bars and stirrup, and 4-the use of an equivalent column with a circular cross-section containing spirals or stirrups. . .

1. Introduction: The primary purpose of this paper is to analyze the uncertainty by assessing gauging deviations of the stage-discharge rating curve in rivers. In this research, the basis of the estimation of the rating curve is the concept of isovel contours in the Single Point Measurement method (SPM). Observed data in the Nazli-chai River in Iran, Main River in England and Colorado River in Argentina are used to investigate the global uncertainty in the rating curve estimation. The results can be used to improve flood control and water resource management. . .

1. Introduction: Recent earthquakes worldwide have illustrated the vulnerability of existing reinforced concrete (RC) beam-column joints to seismic loading. Inadequate shear reinforcement in the existing beam-column joints, especially exterior ones, is believed to be the prime cause of failure/collapse of many moment-resisting RC frame buildings. Hence, effective and economical strengthening techniques to upgrade joint shear resistance in existing structures are needed. Retrofitting using FRP composites has grown in popularity over the last twodecade advantages such as fast and easy installation, high strength/weight ratio, and resistance to corrosion. In this study have been conducted a numerical analysis of 11 RC beam-column joints without FRP and strengthened with FRP in a variety of configurations under cyclic loads. The analyses are performed by ABAQUS finite element program and are calibrated with the experiments. A range of issues in joints, including maximum load, initial stiffness, energy dissipation, load-displacement hysteresis loops, stiffness-displacement curves, and energy dissipation-displacement curves, are investigated. The numerical results were in good agreement with the corresponding experimental ones. The results obtained from the numerical analysis in this study, similar experimental results demonstrated that externally bonded FRP reinforcement is a viable solution towards enhancing the strength, energy dissipation, and stiffness characteristics of RC joints subjected to seismic loads. . .

1. Introduction: The increasing population of the world indicates the development of urban areas, and consequently the use of appropriate methods to improve sandy soils in these areas, led engineers to think of inventing methods to improve the properties of sandy soils. One of these efficient methods to modify the behavior of unsuitable soils in geotechnical engineering is to change the properties of problematic soils, which is called improvement. In this regard, sandy soil is improved by adding materials to improve mechanical properties (compressibility, hardness, shear strength, permeability, etc. ). In this study, the undeniable role of nanoparticles in the improvement of sandy soil and the effect of nanosilica along with bacteria in the biological improvement of soil samples that have not been tested, was investigated (Dejong et al., 2010). Controlling the distribution at the site of bacterial and reactant activity and the results of calcium carbonate distribution and related engineering properties below the soil surface is a major challenge for future improvements, especially if bioremediation in a surface or deep soil system (To replace the method of deep soil improvement with artificial lime). In order to commercialize the bioremediation process, further optimizations in the performance of the biological deposition process (improving the effective use of bacteria, reactants and reducing heterogeneity) should be done (Sharma et al., 2016). Therefore, the aim of this study was to investigate the compatibility of nanosilica with bacteria in order to be able to use minerals to increase the strength of biologically improved soil properties...

1. Introduction: Contamination of soils with petroleum products, in addition to being an environmental problem, also makes it difficult from the point of view of geotechnical engineering and doubts the use of this soil following structures, road pavements, and other constructed structures. Sridharan et al. (1981) reported an increase in soil settlement due to contamination of the region's soil with hydrocarbons, resulting in damage to industrial buildings. In recent decades, due to the importance of studying the geotechnical behavior of contaminated soils with petroleum products, many studies have been conducted on the physical and chemical properties of these soils. Much research has been done on the geotechnical properties of fine-grained and coarse-grained soils contaminated with petroleum products (Shin and Das, 2001, Ratnaweera and Meegoda, 2006, Rahman et al., 2010, Al-Aghbari, 2011, Kermani and Ebadi, 2012, Karpuzcu et al., 2018). In this study, the emphasis is on the evaluation of the polluting effect of gas oil as a pollutant with a specific gravity less than water on the finegrained and coarse-grained behavior of soil. For this aim, a set of geochemical (including XRD and XRF analyzes), geotechnical tests (including grain size distribution, gas evaporation, Atterberg limits, and unconfined compression strength), as well as observation by scanning electron microscopy on contaminated Clayey Sand by gas oil was done. . .

1. Introduction: Engineering and economic investigations in dam construction projects throughout the world indicate that, in many cases, rockfill dams with impervious clay cores are the best selection for the final design (Rezaei and Salehi, 2011). This approach makes the investigation of different issues affecting the stability of rockfill dams worthwhile. In general, dam safety is the first and foremost reason for controlling deformation and physical parameters in dams. Another reason is the importance of basic design concepts for engineers to apply in future designs as well as understanding the resistive and behavioral characteristics of soil and pebbles. One of the most effective approaches for interpreting the mechanical and hydraulic behavior of structures such as. dams is to use data and compare the results with numerical modeling predictions. . .