Modares Civil Engineering journal
Year:2018 | Volume:18 | Issue:2 |Papers Count:22

Trip generation is the first stage of the conventional four-step travel forecasting framework that estimates the number of trips to and from a traffic analysis zone. Using linear regression model is common in this step and generates an acceptable level of performance from the perspective of transport planning, however this model does not incorporate traveler behavior, integer and non-negative nature of trips. To overcome these limitation, several models have been suggested: censored model such as Tobit for deleting negative values; count data models such as negative binomial and Poisson for deleting continuous and negative values; and discrete choice models such as ordered logit and probit for incorporating traveler behavior and preventing continuous and negative values. Given the importance of trip generation stage and lack of sufficient and quantitative attention to various trip production models, this paper develops alternative trip production models. The purpose of this paper is a structural analysis for various trip production models and comparison of their performance in prediction. Four representative models (regression, Tobit, Poisson and ordered logit) are applied to the educational trips in Qazvin city. The modeling unit employed in this study is the household. Research sample includes socio-economic attributes of 4734 households. 85 percent of the data is used for estimation and the rest for validation. The models are assessed by how closely they are able to replicate trips made by each household in the estimation and validation dataset. In order to compare the performance of models in prediction, each of the models is developed on estimation dataset, and used to predict the trips made by each household. Measures assessing how well the predicted number of trips made daily by each household by each of the models compared to the observed number of trip made by the household are evaluated and compared. The four measures for assessing performance are the mean absolute error, regression of the predicted number of household trips against the observed number of household trips in terms of goodness of fit and coefficient of determination, and plot of observed and predicted aggregate trip shares. Results of model building in Stata show that in all four models, number of school students, number of university students, and household car ownership are statistically significant. The performance of each of the models are different in terms of various measures (mean absolute error, regression of the predicted number of household trips against the observed number of household trips in terms of goodness of fit and coefficient of determination, and compare plot of observed and predicted aggregate trip shares). From mean absolute error perspective, ordered Logit and linear regression models have the best performance, but from goodness of fit regression of the predicted number of household trips against the observed number of household trips, Tobit models have the best performance. Ordered Logit models have the best performance in terms of coefficient of determination of the predicted number of household trips against the observed number of household trips and comparison of predicted share of every trip rate level with observed share. The performance of each of the models are similar in prediction of validation and estimation dataset.

Prefabricating is a useful approach for constructing structures in large numbers over a short period of time and is a specific design of structure. Precast structures due to the discrete design and construction of the members have different nature than in-situ structures. The constraints on the construction and arrangement of members in these structures have led to beams with simple and poor connection design. In many cases, resistant moment connection requires a high reinforcement bar density for transferring anchor in the beam, particularly in the joint area. On the other hand, the use of in-situ concrete at the beam to provide the necessary resistance is in conflict with the precast approach. In order to solve these problems, the interior joint of a four-story symmetrical structure with an intermediate moment frame system was compared in two precast and in-situ structures by linear dynamic analysis. The height of each story in considered structure is 3. 2 m and it has 4 bays with 6 m length. Applied load cases include dead, live and earthquake loads. This structure was designed for residential use and earthquake design of it, was based on Iranian code of practice for seismic resistant design of buildings, Standard 2800. Designing of mentioned joints in precast and in-situ cases was based on ACI318-08 and PCI 2004 codes. Moment and shear capacity of beams and columns, splice length of reinforcements, load-moment strength interaction of columns, joint shear, intermediate moment concrete and steel frame specifications, probable plastic hinge region in beams and design order in connection segments were considered in designing process. A finite element based software, ATENA 3D, was used for structural analysis of joints. Nonlinear behavior of concrete, longitudinal and transverse reinforcements and strain concentration of concrete hinge were investigated through this software at this research paper. To study the performance of connection joints through nonlinear finite element analysis, the accurate and idealized definition of applied materials is so essential. Therefore, various material models are used in software. For instance, CEB-FIP model is used to investigate the stress-strain curves and also the concrete-reinforcement bonding, Von Mises plasticity theory is used for post yielding behavior of steel connection segments and interface model is used according to Mohr-Coulomb theory. To study the behavior of connection joints, the force-drift curves, crack opening scheme and measured strain of reinforcements and steel segments are investigated. At this paper, it is attempted to present a moment resistant connection which is simple in manufacturing, transportation and assembly. The results show that the introduced beam and its connection, in comparison with equivalent in-situ connection, performs satisfactorily under the applied efforts in the case of strength, energy dissipation and ductility. Also plastic hinges formation at proposed beams is due to longitudinal reinforcements yielding just like as in-situ beams, but the position of plastic hinges is in far distance from the connection area. In addition to mentioned capabilities, proposed connection can lead to a reduction in reinforcement concentration in beam and also in-situ concrete placing can be eliminated in construction and assembling stages. It has been found that, the proposed precast connection can be presented as a good alternative for currently used moment resistant precast connections.

Optimal financial resource allocation to the seismic retrofitting of the infrastructures and specifying their priority are considered as prominent issues in the macro scale decision making process. As the optimum strategy is adopted and the budget allocation is performed with the appropriate priority, it is expected that a significant loss reduction is achieved. When the financial resources are limited, allocating based on the proper priority seems to be more vital. Urban development has been rapidly progressing in Tehran without the development of proper disaster prevention systems against potential earthquakes. It is urgently necessary to prepare a regional/urban earthquake disaster prevention plan in order to mitigate possible seismic damages in Tehran. The purpose of the study was to understand how the failure of one infrastructure or any of its elements propagates to other infrastructures in order to implement management policies that can mitigate the consequences. In this work, Tehran is initially introduced in aspects of its active faults zone around the city, and its probable earthquake scenarios. In this work, the optimum strategy for retrofitting the infrastructure networks as the water, transportation, communication, gas, and power infrastructures is investigated using Uncertainty Dynamic Inoperability Input-Output Model (U-DIIM). This optimum strategy is adopted against the earthquake impacts in terms of the indirect economic losses, sensitivity to the parameters of the commodity flow matrix and cost of retrofitting strategy. According to the current situations of infrastructures in Tehran, the inoperability of the lifelines, were gathered from the lifeline documents with the help of Tehran Disaster Mitigation and Management Organization-Tehran Municipality, based on the North Tehran fault earthquake scenario. Strategy 1, referred as the “ Do Noth g” strategy th s work wh ch dicates the current situation of lifelines in Tehran Province. In summary, strategies are based on different levels of the reinforcement of the structures and hardening strategies for infrastructures. The cost of implementation, recovery time, and perturbation after earthquakes calculated for each strategy. By minimizing the total economic loss, sensitivity to economic loss parameters and cost of implementation of strategies, the best scenario is selected for the recovery strategy. Therefore, the indices employed in this research include reducing the economic losses and also the sensitivity with respect to the costs associated with the conduction of the strategy. The Pareto method is also used in this work to select the optimal retrofitting strategy. The results reveal that increasing the seismic performance of the infrastructures by 25% is the optimum retrofitting strategy from the economic point of view. Following this strategy, the ratio of economic loss reduction to the strategy implementation costs and also the ratio of the sensitivity reduction to the strategy implementation costs are 0. 3996 and 3. 66, respectively. It is worthwhile to note that all economic interactions between the infrastructures are taken into account in the research.

Electrification is one of the appropriate solutions to increase the railway network capacity. However, use of this solution without provision of the sufficient capacity and required infrastructure through the whole of the network, may not acceptably increase the attracted railway demand. In such cases, the electrification project may be uneconomical. This research aims to propose an algorithm to identify which bottlenecks of the network must be removed, in order to justify the electrification of a specific railway corridor. We investigated the electrification of the railway corridor at north of Iran. This corridor has a substantial capability for absorption of the freight transportation demand. The railway freight demand related to all of the origin-destination pairs of Iranian railway network, along with the capacities of all block sections of the network are considered as inputs of the problem. for freight assignment in the railway network, FARS (Freight Assignment in Railway System) software was used. This Iranian software is developed by transportation research center of Isfahan University of Technology (IUT), in 2013. The assignment method used in this software is based on Incremental assignment. Different scenarios are considered and two main criteria are employed to compare the scenarios: tonnage of increase in railway freight demand, and economic index of benefit to cost called Net Present Value. According to the results, the electrification of the railway corridor at north of Iran, with no resolution of the bottlenecks in other locations of the network, cannot absorb a remarkable demand. The individual electrification of the mentioned corridor can only increase the absorbed freight demand from 1. 65 million tons to 1. 95 million tons, which is not considered an impressive progress. In this scenario, the Net Present Value (NPV) index and Net Uniform Annual (NUA) index are negative, which implies that the execution of this scenario is uneconomical. The low increase of the demand absorption is due to the existence of the capacity bottlenecks in other parts of the railway network. The existence of these bottlenecks prevents the complete usage of the added capacity potential emerged from the electrification. Consequently, the possibility of handling the transportation demand at north of Iran would be limited. By using the algorithm proposed in the present study, the main bottlenecks which prevent the load flow through the network, were identified. Then, by execution of the capacity increase scenarios for the identified bottlenecks, the absorption of the railway freight demand was increased to 3. 97 million tons, with positive values for both NPV and NUA indices, which imply the economic justification of the railway electrification at north of Iran, simultaneously with improvements for capacity bottlenecks at other parts of the railway network. In other words, to achieve the absorption of the freight demand of the railway corridor in north part of Iran, it is not adequate to merely increase the capacity of this corridor itself. The railway electrification project in a specified part of the network is preferred to be performed simultaneously by the capacity improvement projects in other parts of the network. The proposed algorithm can be used in decision making for justifying the railway electrification projects.

Leachate generated in a landfill may not be treated by conventional biological treatment due to its refractory nature and complexity. Aerobic granular sludge is a technology of immobilised microbes that have the potential to improve the existing biological wastewater treatment. In this study, the treatability of municipal leachate by aerobic granulation at bench scale model made of Plexiglas with the dimensions 75 *20*20 cm3 and the volume of 28 litres is experimentally evaluated. In this experimental investigation, the aerobic granules are cultivated from activated sludge seed which is fed by synthetic wastewater. For granules cultivation, the synthetic wastewater containing glucose has been used as the carbon source, the ammonium chloride as the nitrogen source, the potassium dihydrogen phosphate as the phosphorus source as well as the micronutrients such as magnesium sulphate, ferrous sulphate, calcium chloride, potassium dihydrogen phosphate. In this operational program hydraulic retention time of synthetic wastewater in 6-hour cycles containing 30 minutes feeding, 270 minutes’ aeration, 30 minutes settling, 30 minutes’ wastewater discharge, was selected. In this experiment, the temperature in the range of 20-23 C and DO in the range of 6-8 mg/l and PH in the range of 7. 5-8. 3 were controlled. The granulation phase under various organic loading from 50-6000 mg COD per liter and hydraulic shearing in the sequential batch aerobic reactor (SBAR)was cultivated within 28 days. The hydraulic shearing and effective mixing in the reactor was provided by an air lift through a PVC pipe with an internal diameter of 20 cm. In the next stage, the cultivated granules were placed in SBAR and gradually raw leachate was fed into reactor. However, a micro granules of disintegrated were used in the process and granules adapted to leachate at the shorter span of time was developed. In this research parameters such as MLSS, SVI, Velocity, granule Diameter and COD were monitored. Synthetic sewages loading in the 6-hour cycles and the organic loading increases have been done till the formation of granules in 28 days. After each cycle, the parameters mentioned above were examined and the sludge morphology. With the entering of synthetic sewage to the reactor, at first the suspended solids increased and the granules' seeds production reduced. With the consolidation of granules and its sustainability, the leachate is injected into the reactor and is replaced by the diluted leachate. By introducing the raw and diluted leachate to the reactor, some of the granules start to disintegrate which lead to an increase in the amount suspended solids of the system. Due to the change of the raw sewage and replacement of leachate instead of synthetic sewage, in some granules collapse happened. Due to the characteristics of leachate some of the cultivated granules were disintegrated by losing calcium and magnesium which are important cations in cell to cell attachment The results show that when granules are accustomed to the leachate entering the reactor, increase of bacterial activity lead to the improvement of efficiency of leachate treatment in the system and the efficiency of COD removal reached 90%.

Determination of ultimate pile capacity is important for proper design and construction of pile foundations. Most of the time, the pile load test is carried out shortly after the installation of pile. The pile capacity obtained from the load test is often assumed to be the ultimate pile capacity in most of design methods. However, during pile installation, the soil around the pile experiences large deformations and changes in excess pore water pressure, which in turn reduces the shear strength and pile bearing capacity. After the completion of pile driving, the pile capacity increases as the strength of the surrounding soil increases mainly by reconsolidation, manifested by the dissipation of excess pore pressure at the soil-pile interface zone. the ultimate pile capacity could be underestimated if pile load test was carried out while excess pore water pressure still remains, which may lead to a conservative pile design. It should be noted that a pile static load test (SLT) and a dynamic load test (DLT) only measure the pile load– displacement relation and ultimate load at the time of testing; they do not provide any information on pile capacity variations over time. Pile load tests must be repeated at different times to evaluate any set-up effects, which can be time-consuming and costly during pile construction. Therefore, it is essential to develop empirical and numerical solutions to enable analyzing and estimating long-term pile set-up effects on the basis of limited numbers of SLT and DLT tests. Accurate estimation of pile setup, rather than measuring directly in the field, may reduce the cost of piling and still provide the required performance for the pile. Prediction of pile capacity gain with time after driving would certainly be advantageous from an economic standpoint. Incorporating the effects of setup into pile design is expected to reduce the general cost of piling project by reducing pile diameter, pile length, size of driving equipment, and subsequently piling duration. The major reasons for set-up can be categorised into the following two groups: (1) the generation of excessive pore water pressure during pile driving and subsequent dissipationover time, leading to soil consolidation, and (2) the aging process. The purpose of this research is to conduct experimental research aimed at developing an understanding of pile capacity in soft clays and to develop relationship between the pile capacity and elapsed time after the end of initial driving for cohesive soils. An experimental program was developed to study the evolution of pile capacity increase with time for piles driven into a type of soft clay in northern Iran. results of a series of pile load tests conducted on small-scale Aluminum pile foundations driven into soft clay. The piles were tested instantly after driving to measure their initial bearing capacities, and were tested repeatedly over different elapsed times to study the evolution of pile capacity over time. Results show pile capacity increases approximately 80% of initial value, 14 days after initial pile driving. A large proportion of this pile capacity increase over time, also known as setup, was generated within the three days due to fast excess pore water pressure dissipation, and afterward, the pile capacity increased at a lower rate.

Heavy metals are elements that exhibit metallic properties such as ductility, malleability, conductivity, cation stability, and ligand specificity. They are characterized by relatively high density and high relative atomic weight with an atomic number greater than 20. Clay and other soils may become contaminated by the accumulation of heavy metals and metalloids through emissions from the rapidly expanding industrial areas, mine tailings, disposal of high metal wastes, leaded gasoline and paints, land application of fertilizers, animal manures, sewage sludge, pesticides, wastewater irrigation, coal combustion residues, spillage of petrochemicals, and atmospheric deposition. Heavy metal contaminants in addition to geotechnical problems creation and change in the soil strength parameters especially in clay soils, can cause environmental and human health risks due to penetrate through the groundwater. Most commonly heavy metal found at contaminated sites are lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), cadmium (Cd), copper (Cu), mercury (Hg), and nickel (Ni). Also, freezing and thawing cycles have a significant effects on the behavior of stabilized clay soils specially on the heavy metal contaminated clay soils stabilized by cement od other additives. So, by population increasing, advancement of technology and consequently increase in heavy metals emissions, as well as being a quarter of the earth surface in the cold regions and the necessity of building design and construction on these soils, it seems necessary to study the impact of the freezing and thawing cycles on the stabilized clay soils. Different additives such as cement, lime, gypsum, fly ash and other additives were used for stabilization and solidification of heavy metal and oily contaminated soils, the cement is more practical among the stabilizer additives, because of its compatibility with pollutants and high efficiency, low cost and easy access. In this research used cement for stabilization of the lead heavy metal contaminated soil exposed to freezing and thawing cycles. According to the importance of the soil settlement in the clay soils, one dimensional consolidation test was conducted on the experimental samples. Also, due to extensive use of bentonite clay soil in contaminated sites, bentonite clay sample was used for experimental studies. The results of this research indicate that in most cases the critical cycle is a cycle 7. Also, The soil strength parameters such as over-consolidation stress increased about 2 to 8 times in different conditions by cement stabilization. Also, stabilization of heavy metal contaminated by cement clay soils that exposed to freezing and thawing cycles reduce the Cc and Cs coefficients of bentonite clay samples about 50 to 80 percent depending on number of freezing and thawing cycles and heavy metal concentration in bentonite clay sample and also causing preconsolidation in soft clay soils or normally consolidated soils throug the pozzolanic reactions of soil and cement at a low time. Furthermore, the optimum content of cement in contaminated and uncontaminated samples in different freezing and thawing cycles is variable, but in most cases is about 5% to 10% depending on number of freezing and thawing cycles and heavy metal concentration in bentonite clay sample. In continence, stabilization efficacy and the formation of hydrated compounds of cement and clay soil was investigated by using pH chemical test.

In the last decades, the development of nanotechnology has been rising and nanomaterials have been widely used in combination with many traditional materials. The prominent chemical and physical properties of nanomaterials enable them to play an important role in various applications such as modifying the structure of materials, improving the properties of composites, and manufacturing new multifunctional products. Many studies have been carried out on the effect of nanoparticles on concrete performance and most of them demonstrated the improvement of concrete properties. There are a lot of studies on the effect of nanoclay on cement composites. However, there are little researches on the halloysite nanotube (HNT) effect, as subcategories of nanoclay, on the properties of cement composites. Halloysites are a kind of mineral clay which are often produced by air-induced erosion or by thermal transformation of ultramafic rocks, volcanic glasses, and pumice. They are chemically similar to kaolinite but, unit layers in halloysites are separated by a monolayer of water molecules. In general, halloysites have different shapes and exist in the plate, spherical, and tubular forms. The tubular structure is the dominant form of halloysite in nature. Chemically, the outer surface of the HNTs has properties similar to SiO2 while the inner cylinder core is related to Al2O3. Due to the tubular geometry, HNTs like carbon nanotubes could be classified as one-dimensional nanoparticles. Halloysite can grow into long multi-walled tubules, which morphologically resemble to multi-walled carbon nanotubes. In terms of dimensional characteristics, HNTs have an external diameter of about 30 to 190 nm, an inner diameter of about 10 to 100 nm and a length between 3 to 30 μ m. Halloysite characteristics could be sum up as high length to diameter (L/D) ratio, high specific surface, large pore volume, low density in surface, and pozzolanic properties. Mechanical properties of HNTs could make them an ideal reinforcing additive to improve the mechanical properties of cement composites. In addition, due to the nano scale size of HNTs, they can play the role of filler and make a denser and stronger microstructure. Therefore, in this research, the effect of HNTs on the performance of cement mortar was evaluated and the workability and permeability of mortar samples containing 3% halloysite nanotubes were presented. The results indicated an increase of more than 28% of electrical resistance, a decrease of approximately 26% of water absorption rate, 23% reduction in water repellent, a decrease in the workability, and an increment in the rate of hydration of cement mortar due to the incorporation of 3% halloysite nanotube. These results indicate that halloysite nanotubes can be used as an appropriate nanoparticle to improve the properties of cementitious composites. The pozzolanic properties of HNTs enable them to decrease the permeability of cementitious matrices. This could lead to an enhancement in the durability of cementitious matrices.

There are 3 different parameters that play the main roles in fault simulation process and they need to be accurately introduced. The mentioned parameters are seismic source specifications, wave propagation path; and seismic site effects. based on Condition of the region under study there are two different approaches to obtain Attenuation relationships. the first approach is suitable for regions with abundant records of strong ground motion like California, Japan, and Taiwan. In this approach the mathematical model can be used for developing the attenuation relationships employing regression techniques. In the case of using this approach a few parameters like magnitudes, source-to-site distances, and peak ground characteristics are required to develop attenuation relationships. Obviously, the validity and accuracy of these methods strongly depend on data sufficiency, the type of regression technique, and the classification of data. On the other hand, for the regions of limited records of strong ground motion, the first approach may not be appropriate and the application of physical models, as the second approach, will be necessary for successful predicting. In this approach, limited records are basically employed for the physical model calibration. These models usually have been developed in the context of the random vibration theory and the stochastic modeling approach. Among various seismic source specifications, a more physically realistic source model is the specific barrier model or (SBM) for short. The SBM known as one of the most complete, simple, and self-consistent statement of the faulting process which is applicable in both "near-fault" and "far-field" regions. Consequently, the SBM may provide consistent ground motion simulations over the entire necessary frequency range and for all distances of engineering interests. The SBM is specifically more suitable for regions with poor seismological data bank and/or ground motions from large earthquakes with large recurrence intervals. An essential part of the seismological model used in this method is the quantitative description of the far-field spectrum of seismic waves emitted from the seismic source. Since shear (S) wave is primarily the main factor of earthquake damages, the application of stochastic approach of the SBM has almost been focused on the far-field S wave spectrum, in which two corner frequencies of observed earthquake are represented. The ‘ two-corner-frequency’ shows two considerable length-scales of an earthquake source: a length-scale that quantifies the overall size of the fault that ruptures (e. g., the length L of a strike-slip fault) and another length-scale that measures the size of the subevents. Associated with these length-scales are two corresponding time scales: (1) the overall duration of rupture, and (2) the rise time. The SBM has a few main source parameters which have been calibrated to earthquakes of different tectonic regions. In this study SBM used as source model. To make the results comparable with real earthquake (L’ Aquila earthquake), the path and site effects combined with the results of source model. In order to consider path effects, a relation suitable for central region of Italy (Abruzzo) have been selected. Also, to considering site effects theoretical transfer function for linear wave propagation has been computed with the Thomson-Haskell matrix method. Finally, the result of simulation compared with Fourier amplitude of L’ Aquila earthquake.

This paper presents the results of cyclic tests investigating in-plane behavior of URM walls as the main lateral resistant members in school buildings. Generally, URM walls of existing building in the country contain different material properties with different strengths. Therefore, considering the effect of changing in material properties on their failure modes is required. A hypothetical two-story URM building was defined as the prototype structure of the presented cyclic in-plane research study. This prototype structure was selected to be a proper representative of existing URM school buildings in Iran. First story walls of this building with a loading bay equal to five meter were selected as the test specimens. Some properties of specimens were assumed and considered stationary to make the global response of the specimen match with the real condition of existing URM buildings in Iran. For this purpose, the thickness and the height of the walls were considered 0. 35 and 3 m, respectively. The experimental study was carried out on two full-scale specimens. A special height-to-length aspect ratio of the wall was selected to generate enough lateral strength to ensure the bed-joint sliding failure of the URM wall during in-plane cyclic experiment. Lateral strength, Q, of considering URM walls was considered the lesser of the lateral strength based on bed-joint sliding, rocking, diagonal tension or toe crushing strengths. Changing in material properties of walls was considered as the major parameters in the investigation. The specimens were constructed in the structural laboratory of Building and Housing Research Center (B. H. R. C) and subjected to a sequence of cyclic loads. In the construction of walls, similar brick with different mortar and so different strengths were used. According to the results, the behavior of specimens revealed that they could be able to maintain a significant amount of their resistance after cracking without considerable strength degradation, especially for the wall with proper mortar strength. Therefore, URM walls can resist lateral load after formation of the first crack with little loss of strength. According to this ductile behavior of walls and partnership of other elements in lateral load capacity of URM building, the estimation of system strength could be more than limited strength by the first crack of the wall. Changing in material properties of wall affected the failure mode, lateral resistant, displacement capacity, and energy dissipation. The specimen with proper mortar strength experienced bed-joint sliding failure mode, while the specimen with weaker mortar strength experienced mixed sliding-diagonal failure mode. The relationships presented in the standards can present relatively proper prediction for shear sliding capacity of the specimens, while the predicted capacity of them for diagonal capacity is overestimated. Test results showed that improving in the material properties of URM wall improved the lateral strengths of specimens. The wall constructed with the mortar with more appropriate properties revealed more lateral resistant and could experience more deformations. This wall could dissipate much more energy. The experimental m-factors were higher than the current code values for both specimens and improving in the material properties resulted in a considerable increment in m-factor.

One of the most common methods of soil improvement is to use additives in order to improve strength properties and permeability of the soil. Cements or chemicals are usually used as binders for soil particles, which lead to increase the soil shear strength and reduce its hydraulic conductivity (i. e. permeability). Nevertheless, these materials are not suitable for soil improvement in the long term because they require significant natural resources. The use of cement and chemicals for soil improvement is expensive and time-consuming. Management of renewable natural resources (microorganisms and their products) could lead to solve geotechnical and environmental problems and achieve great economic benefits in the building industry. In addition, the application of microbial biotechnology in the building industry make easier some of the existing methods of construction. Using the latest microbial biotechnology, a new type of building materials, namely biocement, has been produced as an alternative to cement or chemicals. Biocementation is the improvement of strength and stiffness of rock and soil by using microbial activity and their products. The process of the formation of precipitates or biocement in the presence of microorganisms is called microbialy induced calcium precipitation (MICP). Biocement can be used in solid and liquid states. In the liquid state, biogrout can flow like water with very low viscosity. Therefore, compared to cement and chemicals, it will be transmitted into the soil, more easily. Naturally, biocement is formed in the presence of microorganisms in ambient temperature and thus, it requires less energy. Because of the abundance of microorganisms in the nature and easy to reproduce with low cost, this type of cement is sustainable. The Microorganisms that are suitable for the production of biocement are usually non-pathogenic and environment friendly. In addition, unlike cement, soil can be improved without disturbance of ground and the environment; since microorganisms can penetrate into the soil and grow in it. This dissertation aims to realize the effect of ground condition on the MICP process in non-cohesive soils. Since this method is still in the laboratory stage, for being used in practical projects, it is required to carry out laboratory experiments, including relative density and particle size distribution, to evaluate the performance of this method in different ground conditions. For this purpose, it was used from Sandy soil with different silt contents of 0%, 5%, 10%, 15% and 20% in two states of Loose (Dr = 40%) and dense (Dr = 100%) conditions in this research. The high urease activity and non-pathogenic bacteria S. Pasteurii was also used in the MICP process. In order to consider the soil conditions on the efficiency of this type of improvement method, uniaxial compressive test parameters and precipitated calcium carbonate content were investigated. According to the results, increasing of silt content from 0% to 20%, leads to reductions of 40% and 46% in precipitated calcium carbonate content, increases of 57% and 41% in the uniaxial strength and increases of 79% and 71% in the elasticity modulus of the samples in two loose and dense conditions, respectively. It seems that these changes were resulted from shrinking of the empty space and increasing of the contact area between the soil particles.

Pile foundations often used to transfer structural loads into deeper layers. On granular soils shaft resistance is an important factor bearing capacity of axially loaded, especially when the pile is subjected to tensile loading. Tensile forces apply on the pile holding the position of ship repair, basements, pumping stations, waterworks structures which are under water. In addition, transmission lines towers, tall chimneys, submerged platforms, masts, and other similar structures that are built on piles, in exposed disturbing moments resulting from wind, earthquakes and sea waves. In such structures, disturbing moments transferred, in some piles for pressure and other piles for tensile load. So, study the behavior of these piles and also effective parameters on the tensile capacity of is very important. Bearing the applied tensile loads on structures is one of the important applications of deep foundations, especially piles. Tensile capacity of these foundations is often produced by the frictional resistance in soil-pile interface. Piles are deep foundations which have considerable acceptance because of multi-applications. Understanding the behavior of piles and prediction of their tensile capacity is so important. In the last three decades various theories have been created regarding the behavior of piles under different loading conditions. The validity of these theories is evaluated by comparing the test results on models or structures piles with the predictions of theoretical. The field tests are Perfect scale and highly desirable, but often costly and difficult. For this reason, laboratory experiments are used to study the behavior of piles under tensile load. But to consider real conditions of the area, especially coastal sites, can be installed the piles in the soil that have been used to study the tensile behavior of piles. The reliability of tension test results in the homogeneous soils and the impact of surface layers of sand in providing friction force are special cases that have not been tested in real conditions of the site. Different methods are developed to achieve safe, constructible and economic design, such as analytical, experimental and in-situ methods, but in some cases they are still subjected to limitations. These methods can’ t neither determine tensile capacity of pipe piles in coastal sand nor examine behavior of them. Since jacking technique is recommended for achieving improved soil properties and eliminating the deficiencies of other installation methods, so investigation of its effect is important. In this method, after jacking the piles with hydraulic jacks, the piles are arbitrarily tested under compressive loading to determine their compressive bearing capacity and then their tensile capacity is determined based on ASTM D-3689 procedure. After reading test data, the ultimate tensile capacity of piles were determined using tensile capacity criteria and then compared with analytical results. Tensile behaviors of piles at large displacements are also investigated and required force for larger pull out displacements were measured. The results showed that determined uplift capacities are more than analytical results and sand compaction due to pile installation can increase frictional resistance. It also revealed that the tangential criterion is determinant to obtain ultimate tensile capacity in most piles.

Soft story in the ground floor is established due to the open space for establishing shops, parking lots or even schools. With regard to the observations of the risks of past earthquakes, such as the 921 Chichi earthquake, Kobe 1995, Bam 2003, and Kashmir 2005, and destructive effects imposed on the soft story, which even caused the collapse of the building. This paper aims to study the effect of near and far fault earthquakes on the two series of mid rise and low rise moment resistance frames. In the both series, a regular frame with the height of 3. 2 meter and two irregular frames with soft ground story with the height of 4. 5 and 5. 5 meters are evaluated. Incremental dynamic analysis is a parametric analysis method that has become common in recent years for estimating the functional level of a complete building under seismic loads. Construction models are created under one or more earthquake records with varying intensity and one or more response curves are produced by the seismic intensity value. The intensity of the records applied on the structure added during analyzes is represented by the parameter IM and the output of the analyzes, which is the response of the construct to the stimulus, with the parameter DM. The IDA curves actually draw the relation between the structure response (DM) to the change in the intensity (IM) of the records. Selected parameters for IM and DM should be well represent the effects of earthquake and structural behavior. The algorithm used for the record scale is a conventional step-by-step algorithm. The step-by-step algorithm can be considered as the easiest way to understand and program. Analyzes continue with increasing levels of IM with equal steps until convergence is achieved (an indication of overall dynamic stability). In this case, the user will only need to select the IM step and the maximum number of dynamic analyzes to get the results. To express the scale level, we need to have a preliminary and temporary selection of IM (which is measurable). After a nonlinear dynamic analysis, one or more curves of the structure response (DM) are obtained in terms of different levels of ground movement (IM). Finally, the performance of the structure is evaluated by defining the extreme states and processing the results using probabilistic relationships. The data obtained from the IDA analysis provides an insight into the behavior of the structure, and is a bridge between the results of the additional static load analysis and the dynamic response In this paper the parameter of IM corresponding to the maximum of inter-story drift and the parameter of DM corresponding to the spectral acceleration of the first mode (T1, 5%) Sa were considered. In addition, the collapse-preventing performance level of CP was analyzed. The results obtained from the fragility curves in the mode of CP indicate that with the height increase of soft story and consequently becoming softer, the ten percent collapse possibility of mid rise structures in the near fault records was decreased more than far fault ones. However in the low rise structures, it has greater reduction in the far fault records than near fault ones.

Sulfate attack is a series of physico-chemical reactions between hardened cement paste and sulfate ions. Sulfate ion penetration into the cement results in the formation of voluminous and deleterious phases such as gypsum and ettringite which are believed to cause deterioration and expansion of concrete; However, there is no direct relationship between ettringite or solids formation during the sulfate attack and the amount of expansion. Concrete deterioration due to sulfate attack depends on multiple elements, however, in experimental studies, the implementation of the elements and obtaining the results in a short time are very difficult. Therefore, the significance of theoretical and software modelling along with in experimental studies, reducing the time and cost, increases so much as to achieve reliable results. Thermodynamic simulations, in this research, are employed according to the method of minimizing Gibbs free energy in order to better understand the external sulfate attack and the behaviour of mortar samples made of ordinary Portland cement and blended cements. GEM software which is able to calculate the stable phase as a function of reactants, temperature and pressure is employed. In this software chemical interactions involving solids, solid solutions, metls, gas/fluid mixture, aqueous electrolyte, (non-) electrostatic surface complexation, and ion exchange can be considered simultaneously in the chemical elemental stoichiometry (+ electrical charge) of the system, i. e. without any mass balance constraints for ligands or surface sites. GEMS simulates various masstransfer processes and reaction paths, such as mixing; But this software cannot replace our knowledge of physical chemistry. It does not apply any restrictions on the calculated hydrate types. This method is based on the theory that states the core samples are never or hardly ever affected by sulfate while the outer layer is in contact with a large amount of sulfate solution. The advantage of this model is that the calculations are very fast but the calculated data are not time dependent. Modelling the sulfate attack is done by increasing the amount of sulfate in cement. Type and volume of phases formed during the sulfate attack and factors affecting that such as cement chemistry, rice husk ash and sulfate solution with different concentrations were studied with the help of this method. Simulation of mortar samples was performed in sodium sulfate with concentrations of 4 and 44 g per liter and 10 and 15 percent rice husk ash substitution. Mortar samples at 20 ° C and water-cement ratio of 0. 5 is assumed. Rice husk ash substitution has an effective role in microstructures improvement, reduced impermeability, and volume of forming products. Sodium sulfate is more dangerous and destructive compared to other sulfates like calcium sulfate or potassium sulfate and forms phases with higher volumes. The results clearly indicate that rice husk ash, consumed portlandite completely and produced maximum volume of calcium silicate hydrate(C-S-H) by 15 percent replacement and also there is not a simple relationship between the increase of formed phases by the penetration of sulfate ions and the observed expansion. Generally, the results correspond to the studies and in experimental results which have examined micro structure.

Contamination of water resources with petroleum products is an environmental problem in the recent decades. There are many different methods for remediation of aquatic environments. Adsorption is considered one of the most effective water remediation techniques. The availability and cost of absorbent is very important factor in the absorption process. In recent years, a wide range of materials were used as adsorbent for remediation of contaminated water. This study was performed to investigate the use of raw red mud as an adsorbent to remove COD from the soluble fraction of gasoline in aqueous solutions. The effects of different parameters including pH, contact time, adsorbent dose and initial concentration of gasoline on the removal process were investigated. It should be noted that all tests were repeated three times. The results showed that increasing pH, from 3 up to 11, increases the efficiency of COD reduction by the sorbent. According to the results, pH of 7 was selected as the optimal pH. The efficiency of COD reduction in contact times of 2. 5, 5, 10, 15, 20, 25, 30, 60 and 120 minutes were studied. The COD reduction by raw red mud occurred quickly at the first step, then proceeds at a slower rate until equilibrium achieved within 15 minutes. Therefore, 15 minutes was considered as the optimum contact time. The effect of adsorbent dosage on the removal of COD of the solution for the values of 1, 2, 5, 10, 15, 20, 50 and 100 g/L was studied. The results showed that with the increasing of adsorbent dosage, the removal rate was increased. Based on the results, the optimal dosage of 10 g/L of raw red mud adsorbent was selected. The COD removal experiments were performed for the initial concentrations of 1%, 2%, 5%, 10% and 20% of gasoline. Removal of COD at low concentrations (1%) was close to 100%. Increasing the initial concentration of pollutant in the aqueous solution decreased the removal rate. Maximum removal of COD (%100) was occurred at the optimum conditions of pH=7, contact time= 15 min, adsorbent dose= 10 g/L, and initial concentration of pollutant= %1. In order to determine the mechanism of adsorption of pollutants to the surface of raw red mud adsorbent, Langmuir, Freundlich and D-R isotherm models were evaluated. Results of the isotherm studies showed a high consistency (R2= 0. 98) with Langmuir isotherm model. It means that adsorption of gasoline on the surface of raw red mud is occurred as single layer, on the homogeneous surface of adsorbent and limited number of adsorbent active sites. Zero order, Pseudo first order and Pseudo second order kinetic models were investigated to determine the rate of the gasoline adsorption on the adsorbent surface. The kinetics of adsorption process was followed a pseudo-second-order model with a correlation coefficient of 0. 99. Parameters such as short contact time, appropriate range for pH, acceptable absorption capacity, low cost and easy accessibility of the absorbent were the advantages of using red mud as an adsorbent to remove COD from soluble fraction of gasoline.

Modal parameter identification of structures is of significant importance in many fields of civil and mechanical engineering. Output-only modal identification methods have gained great attention of civil engineers community in recent years. The algorithms estimating the dynamic parameters (natural frequencies, mode shape vectors and modal damping ratios) of structures just based on the output responses, became popular as operational modal analysis (OMA) or output-only modal analysis or ambient vibration analysis. In the context of OMA, the force acting on the structure should be stochastic, smooth and broadband and there is no need to measure it. Therefore, these methods are appropriate for identification of huge and complex civil structures. One of the most well-established and popular methods of OMA is frequency domain decomposition (FDD) proposed by Brincker et al. Estimation procedure of FDD is based on singular value decomposition of power spectral density matrix of structure responses. Then, the single degree of freedom spectral bell is obtained using modal assurance criteria (MAC) and transformed to correlation function of corresponded degree of freedom by inverse Fourier transform. Later, Brincker et al. presented the enhanced frequency domain decomposition (EFDD) method to estimate not only modal frequencies (with higher accuracy in the comparison with FDD) and mode shapes, but also modal damping ratios. Despite the high capability of EFDD in frequency and mode shape estimation, it still suffers from some limitations in identifying modal damping ratio. This paper first aims to investigate the modal parameters identification by EFDD and explains its merits and demerits and then proposes in-operation modal appropriation (INOPMA) algorithm for use with EFDD to improve the modal damping estimation. The key idea of INOPMA is to realize that the correlation sequence of the system output (subjected to random input) is the sum of decaying sinusoids with a certain phase shift and therefore it may be considered as an impulse response. The convolution of this correlation sequence with a pure sine wave allows the isolation of the mode at a characteristic frequency which depends on the modal damping ratio. By using a force in quadrature of phase with a sine wave, it is possible to estimate the damping ratio which in turn allows the estimation of the undamped natural frequency. In fact, modal damping ratios are first estimated by INOPMA and natural frequencies are then identified based on damping ratio values. By 70 times simulation of a four-story shear frame, capability of proposed method is validated for damping estimation through EFDD analysis. The results are then compared with the ones derived from the typical EFDD method. Regarding randomness of input force, different results are obtained by each new simulation run. So, the comparison process should be performed based on several numbers of simulations. The number of simulation was adopted in a way that the mean or variance of estimated modal damping ratios converges to a constant value. The relative error (the exact value minus the estimated value over the exact value) and variance of the set of the estimated modal dampings are regarded as comparison indexes. Finally, it is shown that by proposed method, the damping ratios are estimated with much less variance and error. Moreover, the ambient vibration test data of Z24 bridge was utilized as a benchmark application case in order to evaluate the capability of the proposed method for modal damping estimation and favorable results were obtained.

The surface protection materials have effective results to prevent concretes from corrosion. Reinforced concrete structures have the potential to be very durable and capable of withstanding a variety of adverse environmental conditions. However, failure in the structures does still occur as a result of premature reinforcement corrosion. There are corrosion protection systems and methods to extend the long-term durability of steel reinforced concrete. For example, application of zinc rich or cement based protective primers to reinforcement, surface protection systems of concrete, Cathodic protection using sacrificial zinc anodes, and conductive anode overlays within an impressed current cathodic protection system. In general, the main duty of surface protection is controlling both physical and chemical damages to concrete in order of preventing or reducing from steel bar corrosion and creating a coat of safekeeping against penetration of chloride ion, carbon dioxide, oxygen, and most importantly water. According to European Norm, three types of protection materials are existed based on function mechanism. Coating, hydrophobic impregnation, and impregnation materials are these systems, and two types of them used in this study. In this study, two materials of surface protection have used on the surface of three types of concrete. Two types of self compacting concrete with different w/c ratio and one ordinary concrete with similar mixture design to one of those SCC were used for estimating of durability of concrete. Epoxy resin and silane-siloxane were two types of surface treatment materials used in this study. SEM analysis and water contact angle test were done to study the function mechanism of surface protection material. The other tests are water vapor permeability, corrosion potential, and corrosion intensity. Some of the results of this study is that using this materials have effective impact on declining of corrosion potential, decreasing of corrosion intensity, and after all increasing durability of concrete. As shown in this paper, all of the protected samples except one, until 49th week did not have a sign of corrosion active phase. Increasing in ratio of W/C in the substrate makes weakness in function of this materials. In the other hand, results of half-cell potential of unprotected samples show SCC2 with 0. 55 w/c ratio and NC with 0. 45 w/c ratio shift from passive to active state in first days and SCC1 with 0. 45 w/c ratio attained its active state in 5 weeks. However once corrosion has started in SCC2-EP in 8 weeks, corrosion rate was lower than unprotected samples. In the presence of surface protection systems, due to their ability to reduce water ingress in concrete, the corrosion intensity in all samples were lower than 0. 23 μ A/ cm^2. The results of water vapor permeability test showed that epoxy can decrease the water vapor permeability up to 65% instead of unprotected concrete. In the meantime, silane-siloxane doesn't have effective results in concrete breathability and have a similar performance to unprotected concrete. The results show using SCC don't have much different effect on quality of the materials function instead of ordinary concrete. Another important result is that protection materials which don't let to enough evaporate, are cause of much corrosion in compare of those that let concrete to breath.

Here, the efficiency of the non-destructive Break-Off (BO) test was investigated for assessing the in-place compressive strength of steel fiber reinforced concrete (SFRC). SFRC was studied due to its advantages in increasing toughness and tensile and flexural strength in particular. To provide a through and comprehensive database, 24 mix designs were selected with cement contents of 400, 450 and 500 kg/m3 with constant water/cement ratio of 0. 4 for all mixes, two maximum aggregate sizes of 12. 5 and 25 mm along with steel fiber volume fractions of 0%, 0. 33%, 0. 67% and 1% for ages of 14, 28 and 90 days. A total of 360 BO tests were carried out in this investigation. Then, effective parameters of SFRC and BO test results were evaluated. In the BO method, the force required to break off an in-place concrete cylinder of 55 mm in diameter and 70 mm long, is related to the compressive strength of the concrete from a predetermined calibration curve developed for concrete mix. The studies showed that volumetric percentage and features of steel fibers had a significant influence on concrete properties as well as BO test results. According to the experimental results it could be generally concluded that the influencing factors, namely, SFRC properties due to presence of steel fibers and BO test significantly affect the results as follows: Generally, for a constant W/C ratio, it can be concluded that raising the cement content increase the mean values of BO strength. It can be stated that the maximum aggregate size within the range of 12. 5– 25 mm has a negligible effect on the BO test results for SFRC with 1% steel fiber volume fractions as the average value of BO strength for 25 mm aggregate concrete was significantly more than the corresponding value for 12. 5 mm aggregate size for plain concrete. Moreover, the improving trend the BO strength with age is observed to be similar for all different concretes. Furthermore, increase of BO strength of SFR concretes respect to corresponding plain value is observed as concrete grows older. In addition, results showed that strength estimation based on a single general calibration curve is not feasible. Therefore, a specific calibration curve for each SFRC should be represented for a realistic assessment and interpretation of results. The coefficient of variation of the BO strength was in range of 4– 11%. The higher values are for concretes with higher amounts of fibers, especially at early ages. The reliability of the method seems to be good in which the coefficient of variation for each group of BO tests are below 11%. It should be noted that even under ideal conditions with a specific calibration it is unlikely that 95% confidence limits of better than ± 15% can be achieved for an absolute prediction of concrete compressive strength. The findings show that higher values are not only due to the lack of precision of the test procedure, but also due to the intrinsic heterogeneity of granular materials like concrete, particularly in presence of higher amounts of fibers.

Buildings in seismic regions are prone to severe damage due to large deformations and low capacity to absorb energy. X-bracing is effectively employed in maintaining the structure stability when earthquakes occur or extreme lateral loads act on the structure. The widespread use of X-bracing systems in steel structures reveals the importance of understanding mid-connections in this kind of braces. When applying a lateral force on X-braces, one structural member comes under tension while the second one is under stress. Buckling occurs to the member subjected to stress and when effective length factor reduces, the member handles a more critical load. X-brace effective length factor is not only influenced by end connection forces but it also depends on mid-connection and its implementation. If the stiffness of tensile bracing is considerable enough, the mid-connection can provide the interaction between the two braces. In fact, should the mid-connection have enough bond, stress brace buckling will be in the second mode. In this state, when the mid-connection slightly changes into a lateral sway, it stops and the stress bracing deforms as double-curved. Nevertheless, in its ideal state, the mid-connection lateral displacement is considered zero. This study aims to design based on Abaqus 3D software the two new mid-connections, flanged joint, and yielding ductile shear panel. Their buckling and post-buckling were also analyzed using nonlinear geometry and materials. In flanged joint, one member is bonded and two other ones are connected to this bonded member. Interior stiffener is used to prevent this bonded member from crushing. Furthermore, in new X-bracing systems instead of mid-connection sheets a yielding ductile shear panel is used. This sample was examined in two modes with and without stiffener. The results indicate that flanged joint increases the critical load and consequently decreases X-bracing effective length factor. This joint also leads to brace buckling coordinate or as it is known as X-bracing second mode buckling. This kind of buckling increases the ultimate strength and decreases displacement outside of bracing member sheet compared to that of the common joint. Furthermore, yielding ductile shear panel connection increases the X-bracing critical load as well as decreases X-brace effective length factor. The using of stiffener in this kind of connection improves loading and reduces X-brace effective length factor. The connection along with the stiffener comes with a 32 percent increase of the X-bracing ultimate strength due to the yielding of the shear panel and the lack of brace buckling. Also, this connection brings about a 23 percent increase in energy adoption by bracing frame. It is important to note that both connections increase the X-bracing behavior factor compared to the common connection. Yielding ductile shear panel connection not only shows the best stress performance among the connections but also with the lowest costs the X-brace can be repaired by changing mid-connection after the earthquake.

Recently, the Iranian code is established for the LRFD design of steel structures that consistent with the Iranian seismic design code (2800-4). This study is aimed to compare the performance of steel moment frames (SMF and IMF) in the Near-faults earthquakes designed with the Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) in a probabilistic framework. After the Static Push over (SPO), new Performance based earthquake engineering (PBEE) approach is incremental dynamic analysis (IDA) that can lead to the probabilistic judgment using fragility curves of the structure under the different types of ground motions at different levels of intensity. For the incremental dynamic analysis a large number of nonlinear time history analysis must be carried out. The evaluated steel moment frames are 4-story and 8-story frames. The nonlinear models of structures are constructed in the Perform-3D software to perform the nonlinear time history analysis. For the nonlinear modelling of beam element, the chord Rotation Model is used that proposed by FEMA and available in the Perform-3D software for the beam elements. This model predict the nonlinear behavior of element in the two end region that plastic hinge may be caused duo to the seismic load of earthquake. For the column elements, the fiber element method was employed. In this method, the cross-section of column element is subdivided into some spring elements. Each spring is subjected to axial load, given by the combination of axial force and bending moment acting on the section. This model sometimes is called multi-axial spring model (MS model). The fiber model represents a section at the structural member-end. This modelling can represent the axial-flexural interaction in the column element that their properties of nonlinear flexural bearing depends on its axial load in each time step. Nearfield events due to their pulse-like effect are in the spotlight in the last decay. To evaluate their effects on the steel structures that located in the seismic areas of Iran, a number of near-field earthquakes are used in the probabilistic assessment. In the IDA curves, the roof drift is used as Damage Measure (DM) and the Spectral Pseudo-Acceleration of the first mode of the structure with 5% modal damping ( 1 (, 5% ) a S T ) is used as Intensity Measure (IM). Also in the probabilistic fragility curves, the direct method is used. It means that the IM is used directly in the fragility curve. To predict the probabilistic function for the different level of performance of structures, the lognormal distribution was used. The study results show that the structures designed by the ASD method have a better seismic performance than the LRFD frames specially in the performance level of Life Safety (LS) and Collapse Prevention (CP). It can be concluded from comparison of the median of collapse functions. For example for the special moment frame (8-story structure), the use of ASD design (instead of LRFD design) leads to a 11% increase in the median of fragility function in the Life Safety (LS) level and 10% increase in the Collapse Prevention (CP) level.

Pipelines are considered as lifelines, because they are used for transportation of different fluids such as natural gas, oil and water on which, the human life depends their existence. The damages to the pipelines are usually associated with human fatalities, financial losses and also environmental pollution. Earthquake wave propagation and permanent ground displacement (PGD) caused by surface faulting are potentially devastating natural events which threaten buried pipelines. Although small regions within the pipeline network are affected by faulting hazards, the rate of the damage is very high since fault movement imposes large deformation on pipelines. On the contrary, the whole of pipeline network is influenced by the wave propagation hazards, but the damage rate is lower which leads to lower pipe breaks and leaks per unit length of the pipe. On the other hand, buried pipelines due to their long length, have to pass through active faults which their large movements may lead to failure and rupture of the buried pipes. It is, therefore, essential to investigate the behavior of buried pipelines against fault displacements in order to mitigate the losses caused by these natural events and to try to keep them in service under various situations. Over the years, many researchers have attempted to analyze pipeline behavior via numerical, analytical an experimental modeling, but most of these works were designed to assess pipe response to strike-slip faulting and some were implemented to recognize the behavior of pipelines under normal faulting with right deformation angles. In the present study, In order to understand the behavior of the pipelines under reverse fault movements, the effects of different geotechnical and geometric conditions on the response of the pipes is examined. Numerical simulations have been conducted using the software ABAQUS based on finite element method. In most of the previous studies, a simplified beam-spring model was used to simulate the behavior of the pipes, but in this study a 3-D continuum model is employed to simulate the behavior of the buried pipes against reverse fault movements. In order to increase the accuracy of the analysis, it is tried to use the elements that the solution has best match with reality of the nature of soil and pipe behavior and the interaction between them. The results of the numerical study confirmed that the compressive strains in pipe caused by reverse faulting are larger than tensile strains, thus compressive strains are considered as the main cause of the failure of the buried pipes in the reverse fault motions. Investigating the pipes behavior in different soil types demonstrated that the buried pipelines in loose and soft soils experience less amount of strain in comparison with those bureid in other types of the soils. This is due to the fact that the displacement of the pipeline in loose and soft soils is easier and there is less soil resistance against pipe displacement. The assessment of the effect of soil dilatation angle illustrated that in large fault displacements, the amounts of pipe strain decline with the reduction in the dilation angle, while changing the modulus of elasticity of the soil has no impact on the response of the pipes. The results also showed that by reducing the burial depth, the level of strain induced in the buried pipes decreases.

Submerged vanes are simple structures that can be used to control the sediment and redistribute the flow in open channels. Submerged vanes are low aspect ratio flow-training structures mounted vertically on the riverbed at an angle to the prevailing flow. The technique of submerged vanes is a new and efficient sediment management method in rivers. Odegard and et al (1991) are the creators of the idea of using vanes, they have chosen the angle of the vanes between 15 to 25 degrees and found that the vortex created by the vanes causes a change in the amount and direction of shear stress and dispersion velocity and depth, is resulting in sediment transport. When a submerged vane is installed in the river bed with a small angle to the flow direction, due to the pressure difference on either side of the vane, vortex and induced circulation is created around the vane. as a result of this vortex, at the downstream of vane, sediment are taken from the suction side of the vane and are deposited on the pressure side of the vane. So by installing a row of vanes on the riverbed, sediment can be distributed over a larger surface. In river meandering, when flow passes through a bend, reduction of flow velocity and rising hydrostatic pressure cause super elevation phenomena at outer side and reduction of water surface at inner-side of the bend. A helical motion results, causing erosion of the outer side of the bend. Installation of submerged vanes on the stream bed can reduce erosion of the outer bank significantly. Most of previous studies in this regard have been tasted in a rectangular flume cross section. In this research use of submerged vane and its influence on the bed topography changes, especially around the bridge pier is studied. Experiments were conducted in the laboratory flume with a 180 degree bend with rational curvature of 2, height of 90 cm, width of 100 cm and a length of straight direction upstream and downstream of the bend respectively 6. 5 m and 5 m. Materials that had been used in these experiments had specific gravity of 1. 5. the diameter of cylindrical pier was 5 cm. With clear water conditions, the water discharge of 70 liters per second, with a depth of 18 cm were tested. The vane was made of 10 mm thick plaxi glass. The height of the vane above the streambed level was 4. 5 cm, 75% of the flow depth and its length is 7. 5 cm (1. 5 D, D= pier`s diameter). Dissimilar arrays of vanes with same angles (25 degree) to main flow direction were employed. Five experiments were carried out considering various positions of the submerged vanes and one experiment was done without the presence of vanes, only with a bridge pier located at 90 degrees. The performance and efficiency of a submerged vane is related to its position. The results illustrate that the experiment with vanes in parallel, by overlapping of 50%, under angle of 25 degrees counterclockwise with the horizon in the direction of flow, has the best performance in control of pier scour protection.