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Laboratory data, which relate the liquefaction resistance of Firoozkooh sand and non-plastic silt mixtures to shear wave velocity are

presented and compared to liquefaction criteria derived from seismic field measurements by Andrus and Stokoe [1]. In the work

described herein, cyclic triaxial and resonant column tests were conducted on specimens of clean sand and sand-silt mixtures with silt

content up to 60%, prepared at different densities. Cyclic undrained strength and small strain shear wave velocity were determined

for identical specimens formed by undercompaction method. It was found that silt content affects cyclic resistance and shear wave

velocity. In addition, the laboratory results indicated that using the existing field-based correlations will overestimate the cyclic

resistance of the Firoozkooh sand-silt mixtures when silt content is 60%. For clean sand and the specimens containing up to 30% fines,

results of this study on cyclic resistance are fairly consistent with Andrus and Stokoe correlations. These findings suggest the need for

further evaluation of the effects of non-plastic fines content upon liquefaction criteria derived from seismic field measurements.

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This paper discusses the applicability of a simple model to predict pore water pressure generation in non-plastic silty soil during

cyclic loading. Several Stress-controlled cyclic hollow torsional tests were conducted to directly measure excess pore water pressure

generation at different levels of cyclic stress ratios (CSR) for the specimens prepared with different silt contents (SC=0% to 100%).

The soil specimens were tested under three different confining pressures (&sigmaƉ= 60, 120, 240 kPa) at a constant relative density

(Dr=60%), with different silt contents. Results of these tests were used to investigate the behavior of silty sands under undrained

cyclic hollow torsional loading conditions. In general, beneficial effects of the silt were observed in the form of a decrease in excess

pore water pressure and an increase in the volumetric strain. Modified model for pore water pressure generation model based on

the test results are also presented in this paper. Comparison of the proposed pore pressure build up model with seed’s model

indicates the advantage of proposed model for soil with large amount of silt.

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Considering normal concrete (NC) the type of concrete need to be vibrated after placing in the formwork, Lightweight

concretes have been successfully applied in the building constructions for decades because of their low specific weight in

connection with a high strength, a high capacity of thermal insulation and a high durability. The development leading to a self

compacting light weight concrete (SCLWC) represents an important innovative step in the recent years. This concrete combines

the favorable properties of a lightweight concrete with those of a self compacting concrete (i.e., the type of concrete need no

vibration after placing in the formwork). Research work is aimed on development of (SCLWC) with the use of light weight

aggregates " Light expand clay aggregate (Leca)". In this investigation, by trial and error procedure, different mix design of

SCLWC were caste and tested to reach a so called standard self compacting concrete in fresh matrix phase such as values of

slump flow, L-box, V-funnel and in hardened phase, the 28 day compressive strength. Based on the results obtained, for two best

so-called standard mix design of SCLWC the stress-strain diagrams are drawn and discussed. Also by three different methods,

the modulus of elasticity of SCLWC are obtained and discussed here. It was found that a brittle mode of failure is governed in

SCLWC.

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In almost all of the present mathematical models, the upstream subbasins, with overland flow as the dominant type of flow, are

simulated as a rectangular plane. However, the converging plane is the closest shape to an actual upstream subbasin. The

intricate nature of the governing equations of the overland flow on a converging plane is the cause of prolonged absence of an

analytical or semi analytical solution to define the rising limb of the resulted hydrograph. In the present research, a new

geomorphologic semi analytical method was developed that tries to establish a relationship between the parallel and converging

flows to reduce the complexity of the equations. The proposed method uses the principals of the Time Area method modified to

apply the kinematic wave theory and then by applying a correction factor finds the actual discharge. The correction factor, which

is based on the proportion of the effective drained area to the analytically calculated one, introduces the convergence effect of

the flow in reducing the potentially available discharge in a parallel flow. The proposed method was applied to a case study and

the result was compared with that of Woolhiser's numerical method that showed the reliability of the new method.

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Compared to conventional chlorination methods which apply chlorine at water treatment plant, booster chlorination has almost

solved the problems of high dosages of chlorine residuals near water sources and lack of chlorine residuals in the remote points

of a water distribution system (WDS). However, control of trihalomethane (THM) formation as a potentially carcinogenic

disinfection by-product (DBP) within a WDS has still remained as a water quality problem. This paper presents a two-phase

approach of multi-objective booster disinfection in which both chlorine residuals and THM formation are concurrently optimized

in a WDS. In the first phase, a booster disinfection system is formulated as a multi-objective optimization problem in which the

location of booster stations is determined. The objectives are defined as to maximize the volumetric discharge with appropriate

levels of disinfectant residuals throughout all demand nodes and to minimize the total mass of disinfectant applied with a specified

number of booster stations. The most frequently selected locations for installing booster disinfection stations are selected for the

second phase, in which another two-objective optimization problem is defined. The objectives in the second problem are to

minimize the volumetric discharge avoiding THM maximum levels and to maximize the volumetric discharge with standard levels

of disinfectant residuals. For each point on the resulted trade-off curve between the water quality objectives optimal scheduling of

chlorination injected at each booster station is obtained. Both optimization problems used NSGA-II algorithm as a multi-objective

genetic algorithm, coupled with EPANET as a hydraulic simulation model. The optimization problems are tested for different

numbers of booster chlorination stations in a real case WDS. As a result, this type of multi-objective optimization model can

explicitly give the decision makers the optimal location and scheduling of booster disinfection systems with respect to the tradeoff

between maximum safe drinking water with allowable chlorine residual levels and minimum adverse DBP levels.

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Since the 1990’s, network reliability has been considered as a new index for evaluating transportation networks under uncertainty. A large number of studies have been revealed in the literature in this field, which are mostly dedicated to developing relevant measures that can be utilized for the evaluation of vulnerable networks under different sources of uncertainty, such as daily traffic flow fluctuations, natural disasters, weather conditions, and so fourth. This paper addresses the resource allocation problem in vulnerable transportation networks, in which multiple performance reliability measures should be met at their desired levels, while the overall cost of upgrading links’ performances should be minimized simultaneously. For this purpose, a new approach has been considered to formulate the two well-known performance measures, connectivity and capacity reliability, along with their application in a bi-objective nonlinear mixed integer goal programming model. In order to take into account the uncertain conditions of supply, links’ capacities have been assumed to be random variables and follow normal distribution functions. A computationally efficient method has been developed that allows calculating the network-wise performance indices simply by means of a set of functions of links’ performance reliabilities. Using this approach, as the performance reliability of links are themselves functions of the random links’ capacities, they can be simply calculated through numerical integration. To achieve desirable levels for both connectivity reliability and capacity reliability (as network-wise performance reliability measures) two distinct objectives have been considered. One of the objectives seeks to maximize each of the measures regardless of what is happening to the other objective function which minimizes the budget. Since optimization models with two conflicting objectives cannot be solved directly, the well-known goal attainment multi-objective decision-making (MODM) approach has been adapted to formulate the model as a single objective model. Then the resultant single objective model has been solved through the generalized gradient method, which is a straightforward solution algorithm coded in existing commercial software such as MATLAB programming software. To show the applicability of the proposed model, numerical results are provided for a simple network. Also, to show the sensitiveness of the model to decision maker’s direction weights, the results of sensitivity analysis are presented..

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This study was conducted to determine the effect of vibration on the curing and compressive strength of lightweight air-trapped

soil (ATS). ATS is manufactured by mixing cement with water and sand and injecting bubbles into the mixture. It is light as

compared to regular soil, can reduce the weight on the ground, and has high fluidity. If ATS is used at construction sites with

many vibration sources, such as pile driving, blasting, and construction machinery, the effect of vibration needs to be seriously

considered. If a road is expanded using ATS to reduce traffic congestion, the ATS quality may decrease because of vibration

generated by traffic moving on the road. In particular, because ATS contains many air bubbles and needs time for curing, the

effect of vibration can be greater than expected. Therefore, the effect of vibration on ATS was evaluated during the curing process

by conducting unconfined compression tests on samples prepared with different values of variables including vibration velocity,

starting vibration time, and mixing ratio. Vibration velocities of 0.25 and 0.50 cm/s did not greatly affect the strength. However,

vibration velocities of above 2.50 cm/s significantly affected the decrease in strength, and the starting vibration time also had a

clear effect on specimens cured for less than 2 hours.

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A new type of infilled frame has been recently proposed. It has a frictional sliding fuse, horizontally installed at the mid-height of the infill. It has already shown that such infilled frames have higher ductility, strength and damping ratio as well as more enhanced hysteresis cycles, compared with regular infilled frames. This experimental paper is focused on the influence of gravitational load on the behaviour of the fused infill panel. Furthermore, a repairing method in which damaged specimens are repaired by grout plasters is also studied. The results show that the gravitational load, applied to the surrounding frame of the infill for the dead or live loads, arises the ultimate strength of the fused infill specimens. It is also shown that repairing the failed specimen by grout was so efficient that the repaired specimen had greater strength than the original one. However, top gap, between the infill and the top beam of the enclosing frame should be absolutely avoided, because it decays the ultimate strength.

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In this paper, an advanced formulation of time-domain, two-dimensional Boundary Element Method (BEM) with material damping is presented. Full space two-dimensional visco-elastodynamic time-convoluted kernels are proposed in order to incorporate proportional damping. This approach is applied to carry out site response analysis of viscoelastic topographic structures subjected to SV and P incident waves. Seismic responses of horizontally layered site, semi-circular canyons, slope topography and ridge sections subjected to these incident waves are analyzed in order to demonstrate the accuracy of the kernels and the applicability of the presented viscoelastic boundary element algorithm. The results show an excellent agreement with recent published results obtained in frequency domain. Also, the effects of different material damping ratios on site response are investigated.

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This paper presents time domain fundamental solutions for the extended Biot's dynamic formulations of two-dimensional (2D) unsaturated poroelasticity. Unsaturated porous media is considered as a porous media in which the voids are saturated with two immiscible fluids, i.e. liquid and gas. At first, the corresponding explicit Laplace transform domain fundamental solution is obtained in terms of skeleton displacements, as well as liquid and gas pressures. Subsequently, the closed-form time domain fundamental solutions are derived by analytical inversion of the Laplace transform domain solutions. Finally, a set of numerical results are presented which verifies the accuracy of the analytically inversed transient fundamental solution and demonstrates some salient features of the elastic waves in unsaturated media..

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In the present study, the application of Endurance Time Analysis (ETA) method is investigated on seismic analysis of a high arch dam. In this method the coupled system is excited using the predesigned intensifying acceleration functions instead of the real ground motions. Finite element model of an arch dam considering the dam-rock-water interaction effects was developed in which the concrete and rock were assumed to have linear elastic behavior. The effect of the large displacement in dam body was considered in numerical model using co-rotational approach. The coupled system was analyzed by conventional Time History Analysis (THA) method in various seismic performance levels and the results were compared with those obtained from ETA at the equivalent target time. It was found that ETA method provides the close results to THA with acceptable accuracy while it reduces the total time of the analyses considerably.

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Well-known seismic design codes have offered an alternative equivalent static procedure for practical purposes instead of verifying design trials with complicated step-y-step dynamic analyses. Such a pattern of base-shear distribution over the building height will enforce its special stiffness and strength distribution which is not necessarily best suited for seismic design. The present study, utilizes a hybrid optimization procedure to seek for the best stiffness distribution in moment-resistant building frames. Both continuous loading pattern and discrete sizing variables are treated as optimization design variables. The continuous part is sampled by Harmony Search algorithm while a variant of Ant Colony Optimization is utilized for the discrete part. Further search intensification is provided by Branch and Bound technique. In order to verify the design candidates, static, modal and time-history analyses are applied regarding the code-specific design spectra. Treating a number of building moment-frame examples, such a hyper optimization resulted in new lateral loading patterns different from that used in common code practice. It was verified that designing the moment frames due to the proposed loading pattern can result in more uniform story drifts. In addition, locations of the first failure of columns were transmitted to the upper/less-critical stories of the frame. This achievement is important to avoid progressive collapse under earthquake excitation.

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It is well-known that the behavior of soil-structure systems can be well described using a limited number of non-dimensional parameters. This is the outcome of researches based on the premise that the foundation is bonded to the ground. Here, it is shown the concept can be extended to systems with foundation uplift. A set of non-dimensional parameters are introduced which controls the main features of uplifting systems. The effect of foundation uplift on response of soil-structure systems are investigated parametrically through time history analysis for a wide range of systems subjected to ground motions recorded on different soil types. In particular, the effects of uplift on displacement ratio, defined as the ratio of maximum displacement of the uplifting system to that of the elastic system without uplifting and drift ratio, defined as the ratio of maximum drift of the structure as a part of uplifting soil-structure system to that of the elastic system without uplifting, are investigated. It is observed that in general foundation uplift reduces the drift response of structures, which in turn, results in lower base shear. The reduction reaches about 35 percent for slender structures located on relatively soft soils subjected to strong ground motions. Simplified expressions are suggested to estimate this reduction in the base shear.

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In this paper, an advanced formulation of the spectral finite element method (SFEM) is presented and applied in order to carry out site response analysis of 2D topographic structures subjected to vertically propagating incident in-plane waves in time-domain. The accuracy, efficiency and applicability of the formulation are demonstrated by solving some wave scattering examples. A numerical parametric study has been carried out to study the seismic response of rectangular alluvial valleys subjected to vertically propagating incident SV waves. It is shown that the amplification pattern of the valley and its frequency characteristics depend strongly on its shape ratio. The natural frequency of the rectangular alluvial valley decreases as the shape ratio of the valley decreases. The maximum amplification ratio along the ground surface occurs at the center of the valley. A simple formula has been proposed for making initial estimation of the natural period of the valley in site effect microzonation studies.

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In this paper, different aspects of the behavior of 2×2 pile groups under liquefaction-induced lateral spreading in a 3-layer soil profile is investigated using large scale 1-g shake table test. Different parameters of the response of soil and piles including time-histories of accelerations, pore water pressures, displacements and bending moments are presented and discussed in the paper. In addition, distribution of lateral forces due to lateral spreading on individual piles of the groups is investigated in detail. The results show that total lateral forces on the piles are influenced by the shadow effect as well as the superstructure mass attached to the pile cap. It was also found that lateral forces exerted on the piles in the lower half of the liquefied layer are significantly larger than those recommended by the design code. Based on the numerical analyses performed, it is shown that the displacement based method is more capable of predicting the pile group behavior in this experiment comparing to the force based method provided that the model parameters are tuned.

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The Dynamic Probe is an effective tool used in site investigation. It is more economic than the use of direct drilling, particularly in explorations with moderate depth. This paper presents an experimental study to investigate the capability of using dynamic probing to evaluate the shear strength and compaction percent of fine soil. A series of dynamic probe tests were carried out at 6 different sites in the Khozestan, Hormozgan and Qom provinces in the central and southern regions of Iran. The repeatability of the results is considered and new empirical equations relating the dynamic point resistance to undrained shear strength and compaction percent are proposed. For undrained shear strength evaluation of fine soils, i.e. clay and silty clay soils, a reliable site-specific correlation between qd and Cu can be developed when considering the correlation between log qd and log Cu. Also compaction present can be evaluated by qd. These equations can be developed to provide site-specific relationships based upon geotechnical data at each new location. Using this approach an estimation of the undrained shear strength Cu and compaction percent CP can be determined from dynamic probe tests with acceptable accuracy. The present paper also encourages the wider application of dynamic probing for site investigation in fine soils.

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This research paper presents the use of wasteful supplementary cementitious materials like fly ash and silica fume to conserve the cement used in concrete. The cement industry is one of the major producers of greenhouse gases and an energy user. In this study, Portland cement was used as a basic cementitious material. Fly ash and silica fume were used as the cement replacements by weight. The replacement levels of fly ash were 30%, 40% and 50%, and silica fume were 6% and 10%. The water binder ratio was kept constant as 0.4 and super plasticizer was added based on the required workability. Results of the binary and ternary concrete mixtures compressive strength, split tensile strength and flexural tensile strength were taken for studyup to 90 days. Based on the experimental results of compressive strength, prediction models were developed using regression analysis and coefficients were proposed to find the split tensile strength and flexural strength of binary-ternary concrete mixtures at 28 and 90 days.

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Steel-concrete hybrid systems are used in buildings, in which a steel structure has been placed on a concrete structure to make a lighter structure and have a faster construction. Dynamic analysis of hybrid structures is usually a complex procedure due to various dynamic characteristics of each part, i.e. stiffness, mass and especially damping. Dynamic response of hybrid structures has some complications. One of the reasons is the different stiffness of the two parts of structure and another reason is non-uniform distribution of materials and their different features such as damping in main modes of vibration. The available software is not able to calculate damping matrices and analyze these structures because the damping matrix of these irregular structures is non-classical. Also an equivalent damping should be devoted to the whole structure and using the available software. In the hybrid structures, one or more transitional stories are used for better transition of lateral and gravity forces. In this study, an equation has been proposed to determining the equivalent uniform damping ratio for hybrid steel-concrete buildings with transitional storey(s). In the proposed method, hybrid buildings are considered to have three structural systems, reinforced concrete, transitional storey and steel. Equivalent uniform damping ratio is derived by means of a semi-empirical error minimization procedure.

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Construction industry projects impose unsought constraints on employers to manage and define new projects including investment risk, performance variation and diversity of the project. Annually, a significant part of the governmental budget is being spent to execute water and wastewater projects in Iran. However, further projects are on demand to develop the country. The aim of this study is to develop courses of action to attract private partnership into the projects defined and executed in the water sector of the Iranian Ministry of Energy. To determine the criteria and implementing the proposed strategies, SWOT (Strength, Weakness, Opportunity, Threat) method was used as a powerful tool for understanding the context of the organization. To understand the importance of criteria, we weighted them then the extracted strategies from SWOT matrix (ANP method) was prioritized and divided into short- and long-term range in terms of performance and capabilities. According to the results, SO strategies have more weight than other strategies. Therefore, regarding the nature of strategies, the opportunities should be completely used through reinforcing the strengths and short- and long- term periods planning.

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A study has been conducted on the bearing capacity of strip footings over sandy layered soils using the stress characteristic lines method. Traditional bearing capacity theories for specifying the ultimate bearing capacity of shallow foundations are based on the idea that the bearing layer is homogenous and infinite. However layered soils are mainly happening in practice. The stress characteristic lines method is a powerful numerical tool in order to solve stability problems in geotechnical engineering. In the present paper, an appropriate algorithm is derived for estimating the static bearing capacity of strip footing located on two layered soils using the stress characteristic lines method. Some numerical and experimental examples are presented in order to validate the proposed algorithm. Some graphs and equation are presented for initial estimating the effective depth of strip footings located on two layered soils.