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Showing 63 results for Relationship

Masoud Ghodsian ,
Volume 2, Issue 1 (3-2004)
Abstract

The flow characteristics of triangular weir are studied under free and submerged flow condition. This paper reports the results of an investigation carried out to establish the stage-discharge relationship for sharp and broad crested triangular weir. The stage-discharge relationships are deduced by the application of the theorem of the dimensional analysis and the incomplete self-similarity theory coupled with experimental data.
Baziar M.h., Asna Ashari M.,
Volume 2, Issue 3 (9-2004)
Abstract

An experimental study was carried out to evaluate the liquefaction resistance of silty sand utilizing laboratory techniques. In this study, liquefaction potential of silty sand by using cyclic triaxial tests on frozen samples retrieved from calibration chamber and constructed samples by dry pouring method were investigated. Correlation between cone penetration resistance and cyclic strength of undisturbed silty sand samples are also examined using CPT calibration chamber and cyclic triaxial tests. The cone penetration tests were performed on silty sand samples with fine contents ranging from 0% to 50% and overburden stresses in the range of 100-300 kPa. Then the soil sample in calibration chamber, in the same way that soil samples were prepared during CPT sounding, was frozen and undisturbed soil specimen retrieved from frozen soil sample were tested using cyclic triaxial tests. Analysis of results indicates that the quality of frozen samples is affected by fine content and overburden pressures. Also, using data obtained in this research, the relationship between cone tip resistance and cyclic resistance ratio (CRR) for silty sand soils will be presented. These correlations are in relatively good agreement with field case history data. Also increasing confining pressure in silty sand material increases the cone tip resistance and generally, cyclic resistance ratio increases by increasing silt content.
M.m. Alinia,
Volume 2, Issue 4 (12-2004)
Abstract

One main factor in design of panels subjected to axial loading is their buckling behaviour. The design of stiffeners in a metal or composite plated structure is the key factor for safety and weight reduction. This work presents a parametric study on the optimal types and geometrical properties of stiffeners in plates under in-plane axial loads. The results show that flanged type (such as T or L) longitudinal stiffeners increase the normal critical stresses by at least 28% compared to non-flanged stiffener. It is also shown that the optimum geometric properties of stiffeners correspond to the point when the buckling shape of a plate changes from the overall to local mode. Also it is illustrated that for these optimal instances, there always is a linear relationship between the cross-sectional area ratio and the rigidity ratio of the stiffeners to the plates. Finally, Sample relationships for plates having different number of stiffeners are presented.
M.h. Alipour, H. Emamifar,
Volume 3, Issue 2 (6-2005)
Abstract

Partnering is the master key element for project quality. It opens the doors to commitment and communication between the parties and provides the mastic which turns disparate groups with varying aims into a coherent team with common objectives (Baden-Hellard).There has been considerable business emphasis placed upon the development of collaborative relationships across companies in recent years. Construction is no exception. The presence of trust in the relationships has been cited as central to successful business and project outcomes (Partnership Sourcing Ltd. 1994, Latham1994). Trust is central to the development of non- adversarial business relationships, and hence provides fertile ground for the development of practices such as partnering, strategic alliances and supply chain management.The paper focuses upon the partnering concept in construction and discusses the role of trust as a key dimension for reducing adversarial relations in project working environments.
Mahmoud Saffarzadeh, Maghsoud Pooryari,
Volume 3, Issue 2 (6-2005)
Abstract

This paper specifies the relationship among various factors contributing to road accidents including geometrical design characteristics, environmental and traffic specifications, by multiple regression analysis. The main objective of this paper is identification of problems associated with the safety issue of road networks by application of accident prediction models. Data from previous accidents were used to develop the models. Results of this study showed that the rate of road accidents is to a large extent dependent on the rate of traffic volume. Type of road and land-use are other important factors influencing the number and intensity of accidents. The mountainous roads in this respect require special attention regarding their safety factors. The quantitative rate of road safety upgrading has also been specified by adding traffic lanes in road networks.
B. Zahabiyoun,
Volume 4, Issue 1 (3-2006)
Abstract

A methodology is presented for the stochastic generation of daily rainfall which accounts for changes to the climatic inputs. The focus of the study is an example catchment in Iran. The methodology addresses the inability of GCMs to provide suitable future scenarios for the time and space scales required for a water resource impact assessment for a small catchment. One stochastic model for rainfall (Neyman-Scott Rectangular Pulses, NSRP, model) is used to generate daily rainfall sequences and then validated using historic records. For present climate conditions, the NSRP model is fitted to observed rainfall statistics. GCM outputs are then downscaled using regressions between atmospheric circulation indices (ACIs) and rainfall statistics. The relationships are then used to predict the rainfall statistics for future conditions using GCM outputs. In this respect, climate change impacts are studied and assessed in this paper. Generated rainfall scenario can then be used as inputs to a rainfall-runoff model in order to generate daily streamflow data which is not investigated here.
M. Naderi,
Volume 4, Issue 2 (6-2006)
Abstract

This paper introduces an innovative partially destructive method, called “Twist-off”, for the assessment of in situ concrete strength. In this method a 40mm diameter metal probe is bonded to a concrete surface by means of a high strength epoxy resin adhesive. To measure the concrete compressive strength, a torque is applied using an ordinary torque-meter and the maximum shear stress at failure is used to estimate the cube compressive strength by means of a calibration graph. The relationship between the results of this new method and compressive strengths of concrete cores is also presented in this paper. The average coefficient of variation of the results of this method was seen to be of the order of 8 percent and the correlation coefficients of its comparative results with concrete cube and core compressive strengths were found to be 0.97 and 0.90 respectively. In order to assess the performance of this method on site, tests were undertaken on a number of buildings. Although the method was found to perform well but with some of the structures tested, the differences between the strengths of sample cubes and estimated in situ compressive strength of concrete were seen to be significant.
M.kazem Sharbatdar,
Volume 6, Issue 1 (3-2008)
Abstract

FRPs (fiber reinforced polymer) possess many favorable characteristics suitable and applicable for construction industry when compared with steel reinforcement. There are new ideas to use FRPs as longitudinal or transverse reinforcement for new concrete elements particularly for bridge decks or beams. Although high tensile strength of FRP is main characteristic for applications at both areas, its weakness to bending and linear stress-strain behavior with virtually no ductility, makes it vulnerable to probably premature failures under reversal tension-compression loading during earthquake. A pilot research project has been conducted to explore the characteristics of large-scale cantilever concrete beams reinforced with FRP re-bars and grids and were tested under either simulated cyclic loading or monotonically increasing lateral loading. This paper presents the test parameters and results obtained during research. The analytical relationships are compared with those recorded experimentally, and test results showed the diagonal cracks and either rupturing of FRP bars in tension or stability failure in compression bars at long or short shear span beams. The comparison of nominal moment capacities between analytical and experimental values confirms that plane section analysis is applicable to FRP reinforced concrete members.
M.a. Khan, A. Usmani, S.s. Shah, H. Abbas,
Volume 6, Issue 2 (6-2008)
Abstract

In the present investigation, the cyclic load deformation behaviour of soil-fly ash layered system is

studied using different intensities of failure load (I = 25%, 50% and 75%) with varying number of cycles (N =

10, 50 and 100). An attempt has been made to establish the use of fly ash as a fill material for embankments of

Highways and Railways and to examine the effect of cyclic loading on the layered samples of soil and fly ash.

The number of cycles, confining pressures and the intensity of loads at which loading unloading has been

performed were varied. The resilient modulus, permanent strain and cyclic strength factor are evaluated from

the test results and compared to show their variation with varying stress levels. The nature of stress-strain

relationship is initially linear for low stress levels and then turns non-linear for high stress levels. The test

results reveal two types of failure mechanisms that demonstrate the dependency of consolidated undrained

shear strength tests of soil-fly ash matrix on the interface characteristics of the layered soils under cyclic

loading conditions. Data trends indicate greater stability of layered samples of soil-fly ash matrix in terms of

failure load (i) at higher number of loading-unloading cycles, performed at lower intensity of deviatoric stress,

and (ii) at lower number of cycles but at higher intensity of deviatoric stress.


Saeed Ghaffarpour Jahromi, Ali Khodaii,
Volume 6, Issue 4 (12-2008)
Abstract

In this study an empirical model which can be used to predict the rutting parameter (G*/sinδ) for neat and powder rubber modified bitumen describes. The model was developed using 36 unique powder rubber modified bitumen combinations, rubber concentrations were varied at 5% intervals between 5 and 20%. The effects of powder rubber particle size on model accuracy were also studied ultimately a model was produced with the capability of predicting rutting parameter values over a range of temperatures and rubber concentrations. By definition, the upper limit of the performance grade is dependent on the rutting parameter value therefore, the relationship was also considered in terms of high end failure temperature. The Rubber Coefficient for rutting parameter (Rcg) was identified as an important parameter in the estimation of rutting parameter (G*/sinδ) with the addition of powder rubber. This term is a quantitative representation of the increase typically witnessed in rutting parameter values with the addition of powder rubber. Ambient ground powder rubber exhibited higher Rcg values than cryogenically ground particles. Additionally, 95% confidence intervals were generated for the predictive model thus providing a range of accuracy for the model. The resulting confidence intervals were approximately +/-1300 Pa these confidence intervals were seen to capture 92.6% of the 462 data points used. Findings from this research suggest that the differences between cryogenic and ambient powder rubber bitumen are accurately described using the Rcg, furthermore bitumen properties may be predicted using an empirical equation.
A. Hamidi, M. Alizadeh, S.m. Soleimani,
Volume 7, Issue 1 (3-2009)
Abstract

There are limitations in experimental studies on sand-gravel mixtures due to the small size of testing

specimens. Due to this problem, many researchers have worked on prediction of the shear strength of mixture by testing

the sandy fraction of soil alone and developed empirical relationships. Most of the previous relationships have been

determined for low surcharge pressures in which particle breakage does not affect the shear strength parameters.

However, the particle breakage affects the relationships in higher confinements. At the present study, the results of

large scale direct shear tests on sand and sand-gravel mixtures was used to investigate the shear behavior and

dilatancy characteristics in a wider range of surcharge pressures. The gravel content, relative density, surcharge

pressure and gravel grain size were considered as variables in testing program. The relationships between shear

strength characteristics of sand and sand-gravel mixtures were determined considering dilation characteristics of the

soil. In this regard, the minimum void ratio was found as a useful indirect index that relates uniquely to the critical

state friction angle independent of soil gradation. The relations between critical state or peak friction angles of the

mixture with minimum void ratio were determined as a function of surcharge pressure. The correlations could be useful

for determination of the strength parameters of sand-gravel composites by testing sandy fraction of mixture.


R. Abbasnia, M. Kanzadi, M. Shekarchi Zadeh, J. Ahmadi,
Volume 7, Issue 2 (6-2009)
Abstract

Drying shrinkage in concrete, which is caused by drying and the associated decrease in moisture content, is one of the most important parameters which affects the performance of concrete structures. Therefore, it is necessary to develop experimental and mathematical models that describe the mechanisms of drying shrinkage and damage build up in concrete. The main objective of this research is the development of a computational model and an experimental method for evaluation of concrete free shrinkage strain based on the internal moisture changes. For this purpose and for modeling of moisture losses in concrete members a computational program based on finite element approach and the modified version of Fick's second law in which the process of diffusion and convection due to water movement are taken into account, is developed. Also the modified SDB moisture meter was used to measure the internal moisture changes in concrete. Based on the obtained results, calculated humidity is in good agreement with measured data when modified Fick's second law with diffusion coefficient from Bazant method were used, and are very reasonable for determining the moisture gradient. Also, the predicted value of shrinkage strain from the proposed method is in good agreement with measured data and also the established relationship can be used for determine the distribution of shrinkage strains in concrete members.
M.h. Sebt, A. Gerei, H. Naghash Toosi,
Volume 7, Issue 3 (9-2009)
Abstract

Risks mean cases of uncertainty of project, the impact of which is realized as a threat (negative aspect) and/or opportunity (positive aspect). The traditional viewpoint on risk is a negative viewpoint that implies damages, loss and harmful consequences. Judgments such as this on risk merely emphasize on risks management and pay less attention to opportunities management. It is clear that some uncertainties might be profitable for the project as in many cases, it could be the source of loss. In a developed attitude, focus is made on a common process that could address the integrated management of both opportunities and risks to aim at maximizing the positive effectsopportunities-, and minimizing negative effects- risks-. Therefore, existence of causal-effect relations between risks, relationship, effects of risks and opportunities on each other and variety of strategies in facing risks gives no alternative for risk management team than taking integrated management of risks and opportunities. In another word, reaction to risks, with respect to risks and/or relevant opportunities, separately, will be never effective. In this paper, for the purpose of integrated management of risks and opportunities, the stages of quality analysis and reactions to risk are combined. The method which is used for reaction towards risk is a procedure based on dynamic system. Dynamic system is highly important among uncertainties due to considering the type and intensity of effects. By using dynamic system and attention to the relationship between uncertainties (risks/ opportunities), reaction to risk and decision making on employing suitable strategies to face risks will be more precise and accurate.
M. Bastami, F. Aslani, M. Esmaeilnia Omran,
Volume 8, Issue 4 (12-2010)
Abstract

Structural fire safety capacity of concrete is very complicated because concrete materials have considerable variations. In this paper, constitutive models and relationships for concrete subjected to fire are developed, which are intended to provide efficient modeling and to specific fire-performance criteria of the behavior of concrete structures exposed to fire. They are developed for unconfined concrete specimens that include residual compressive and tensile strengths, compressive elastic modulus, compressive and tensile stress-strain relationships at elevated temperatures. In this paper, the proposed relationships at elevated temperatures are compared with experimental result tests and pervious existing models. It affords to find several advantages and drawbacks of present stress-strain relationships and using these results to establish more accurate and general compressive and tensile stress-strain relationships. Additional experimental test results are needed in tension and the other main parameters at elevated temperatures to establish well-founded models and to improve the proposed relationships. The developed models and relationships are general, rational, and have good agreement with experimental data.


J. Vafaie, T. Taghikhany, M. Tehranizadeh,
Volume 9, Issue 1 (3-2011)
Abstract

The near field ground motions have a high amplitude pulse like at the beginning of the seismogram which are significantly influenced by the rupture mechanism and direction of rupture propagation. This type of ground motion cause higher demands for engineering structures and its response spectrum is dramatically different than far field spectra.

Tabriz is one of the ancient cities in

Azerbaijan province with many industrial factories, financial centers and historical monuments in North-West of Iran. In this region, North Tabriz Fault which has a well known history of intense seismic activity is passing through in close distance of urban area. In this regard investigation of near field ground motion effect on current practice seismic design spectrum in this region is necessary.

Hence, probabilistic seismic hazard analysis is carried out using appropriate attenuation relationship to consider near field effect. The peak ground acceleration (PGA) and several spectral accelerations (SA) over bedrock are estimated for different return periods and maps of iso acceleration contour lines are provided to indicate the earthquake hazard in different points of

Tabriz city.

Afterward, the generated horizontal equal-hazard spectrums considering near field effect are compared with different spectrums developed base on simple pulses model for near field motion. Both types spectrum used to verify current practice seismic design spectrum of Iranian code (2005) and International Building Code (IBC 2000). The results reveal the long-period structures which are seismically designed based on current practice seismic codes are in high risk to be damaged during near fault ground motion.


Hasan Ghasemzadeh, Ms. Esmat Akbari Jalalabad,
Volume 9, Issue 3 (9-2011)
Abstract

In this study compressive strength of carbon nanotube (CNT)/cement composite is computed by analytical method. For this purpose representative elementary volume (REV) as an indicator element of composite is chosen and analyzed by elasticity relationships and Von mises' criterion applied to it. It is assumed that carbon nanotubes are distributed uniformly in the cement and there is perfect bonding in the interface of cement and nanotube. At first for simplicity of computations, carbon nanotubes ( CNTs) are assumed to have unidirectional orientation in the cement matrix. In following, the relations are generalized to consider random distribution of nanotubes in cement, and a new factor suggested for random orientation of fibers in the CNT/cement composite. The results of analytical method are compared with experimental results.


M. Jahanandish, M. Veiskarami, A. Ghahramani,
Volume 9, Issue 4 (12-2011)
Abstract

Foundations behavior is affected by soil behavior which can vary from dilative to contractive depending on the stress level,

particularly in dense frictional soils. The Zero Extension Lines (ZEL) method has been generally developed to predict the

foundations behavior. Knowledge of soil behavior enables the ZEL method to predict the general and local shear failure modes.

In this paper, a relatively simple work hardening/softening soil constitutive model is developed to represent dense frictional soils

behavior under different stress levels. This model is based on the accumulation of the plastic work during a simple direct shear

test and its relationship to stress ratio to establish the hardening law. Verifications have been made for the developed soil model.

The model is then implemented into the ZEL method to theoretically investigate the bearing capacity and load-displacement

behavior of foundations over dense frictional soils. Utilization of this model enables the ZEL method to capture different modes

of failure depending on the foundation size. A numerical study on foundations behavior was performed showing the ability of the

presented approach in capturing both failure modes.


R. Attarnejad, F. Kalateh,
Volume 10, Issue 1 (3-2012)
Abstract

This paper describes a numerical model and its finite element implementation that used to compute the cavitation effects on

seismic behavior of concrete dam and reservoir systems. The system is composed of two sub-systems, namely, the reservoir and

the dam. The water is considered as bilinear compressible and inviscid and the equation of motion of fluid domain is expressed

in terms of the pressure variable alone. A bilinear state equation is used to model the pressure–density relationship of a cavitated

fluid. A standard displacement finite element formulation is used for the structure. The Structural damping of the dam material

and the radiation damping of the water and damping from foundation soil and banks have been incorporated in the analysis. The

solution of the coupled system is accomplished by solving the two sub-systems separately with the interaction effects at the damreservoir

interface enforced by a developed iterative scheme. The developed method is validated by testing it against problem for

which, there is existing solution and the effects of cavitation on dynamic response of Konya gravity dam and Morrow Point arch

dam subjected to the first 6 s of the May 1940 El-Centro, California earthquake, is considered. Obtained results show that impact

forces caused by cavitation have a small effect on the dynamic response of dam-reservoir system.


A. R. Shokoohi, B. Saghafian,
Volume 10, Issue 1 (3-2012)
Abstract

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.


B.l. Kirov, N.n. Truc,
Volume 10, Issue 2 (6-2012)
Abstract

Soft soil in Hanoi, Vietnam, is mainly originated from lacustrine and shallow-sea sediment. This is the youngest formation with
around 3000 years of age. To serve the research purpose, clayey soil samples at ten areas in Hanoi and some places in the RRD
are prepared. Mineral composition of soils determined by X-ray diffraction analysis shows that clay minerals are predominated
by Illite, Kaolinite, Chlorite, and Montmorillonite respectively. Many previous researches indicated that in saline-saturated
condition, types of cation in saline water and types of clay mineral in soil layers, as well as their predomination decide the
changing process of geotechnical properties in other manner. In this paper, the initial relationship between geotechnical
properties and clay mineral composition of Hanoi soft soils in saline-saturated media is established



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