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Showing 14 results for Hou

E. AsHouri ,
Volume 2, Issue 3 (September 2004)
Abstract

The seismographic data, as well as historical resources are indicative of the occurrence of numerous earthquakes in the region of Garmsar since the prehistoric centuries. The 4th century BC earthquake in the region of Caspian Gate and Eivankey City with the magnitude of Ms = 7.9 and intensity of Io = X and also the earthquake of spring 743 AD, (Spring 122 Hegira, Solar year)estimated at the magnitude of Ms= 7.2 and intensity of Io = VIII in the region of Sardarreh Khar (Caspian Gate) and Takhte-Rostam Mountain, and earthquakes of Moharram 1367(3th of September, 1988) continuing for one year, inspired the author to investigate and introduce the causing factors of these earthquakes. In this research, it has been identified that on one hand factors such as activation of certain unknown faults.The geographical distribution of the seismological focus properly indicate Garmsar,s fault activation and the faults of Rude-Shur valley, Ejdeha Mountain and the faults of north and south part of Kalarz Mountain and Red Mountain, Rameh, Ghalibaf, Gach-ab and Gugerd Mountain faults have been acted in the past history of this region (Fig. 2).
Khalou A.r., Ghara CHour Lou A.,
Volume 3, Issue 1 (March 2005)
Abstract

This paper presents the results of analytical studies concerning the flexuralstrengthening of reinforced concrete beams by external bonding of high-strength lightweightcarbon fiber reinforced plastic (CFRP) plates to tension face of the beam. Three groups of beamswere tested analytically and compared with existing experimental results. Results of the numericalanalyses showed that, although addition of CFRP plates to the tension face of the beam increasesthe strength, it decreases the beam ductility. Finite element modeling of fifteen different beams in aparametric study indicates that steel area ratio, CFRP thickness, CFRP ultimate strength andelastic modulus considerably influence the level of strengthening and ductility.
FarHoudi J., Shah Alami H.,
Volume 3, Issue 1 (March 2005)
Abstract

The rectangular broad crested weirs are widely used to measure the water dischargewhich is one of the most popular tools in the irrigation canals particularly, in developingcountries.The present article is trying to demonstrate the results of an experimental work carriedout on rectangular broad crested weir with sloped upstream face to investigate the effect ofupstream slope on discharge efficiency. The upstream slope was varying from 90 to 23 degreeswhile incoming discharge was ranging from 14 to 75 lit/ sec. The experiments were conducted in aflume with a weir of fixed height under the normal downstream water depth .It is revealed that theslope of upstream face in rectangular broad crested weir would smoothen the flow profile havingthe critical depth on the weir crest adjacent and upstream of downstream edge of the weir . Theresults also lead to a novel achievement showing that the weir discharge efficiency is dependenton the slope of upstream face of the weir. As the slope of upstream face of the rectangular broadcrested weir is decreasing from 90 to 23 the weir discharge efficiency is increasing and reachingto its maximum through a parabola function at slope angle of 25 degrees(i.e. 1:2.15). Theinvestigation also showed that the depth of flow over the weir crest, the specific energy head ofthe approaching flow relative to chanel bed and the critical depth would be a pertinent similarityscales to asses the flow behavior over different sloped rectangular broad crested weirs betweenmodel and prototype. However, some broad investigation is recommended to endorse theachievements.
Prof Javad FarHoudi,
Volume 7, Issue 4 (December 2009)
Abstract

ABSTRACT

Induced total pressure by flow, including mean and fluctuating components, around a selected chute block in SAF stilling basins downstream of an ogee spillway was studied. Several pressure holes were selected on various faces of a selected chute block to get enough information regarding the total pressure field. This paper reports the results of an experimental work and measurement of mean and fluctuation pressures around chute blocks of SAF stilling basins. The observations showed that the maximum total pressure varies inversely with Froude number of incoming flow while its position of occurrence follows a quadratic polynomial relation ship. Statistical analysis also showed that the peak instantaneous pressure fluctuations could be as large as ±4.5times the RMS value.It is concluded that pressure fluctuation around the chute blocks may double the magnitude of pressure field around the chute blocks and can not be overlooked in designing such appurtenances.


Hamed Farshbaf Aghajani, Abbas Soroush, Piltan Tabatabaie SHourijeh,
Volume 9, Issue 4 (December 2011)
Abstract

Evaluating the rate and maximum height of capillary rise is of prime interest in unsaturated soil mechanics. Antecedent solutions

to this problem have dwelled mostly on determining the maximum capillary rise height, overlooking moisture and suction changes

in the capillary region. A comprehensive improved solution for the capillary rise of water in soils is presented. Salient features of

the formulation including consideration of initial soil suction (if any) prior to capillary rise, and determination of water content

variation in the capillary region are elaborately discussed. Results reveal that suction head variation within the capillary region

is non-linear, where the curvature decreases as water rises to higher elevations. The solution is verified and compared with

existing solutions, by means of two sets of experimental data available in the literature. The comparison suggests that the

improved formulation is more accurate and versatile than previous solutions for capillary rise.


H. Behbahani, H. YagHoubi, M. A. Rezvani,
Volume 10, Issue 1 (March 2012)
Abstract

Magnetic levitation (maglev) is amongst the most advanced technologies that are available to the transportation industries. It

has already been noticed by decision makers in many countries around the globe. Contrary to such high levels of interest, there

are no practical algorithms available to the engineers and/or managers to assist them in analyzing economics of the maglev

systems. Therefore, it has been the purpose of this research to find appropriate answers to such vital questions and also investigate

feasibility for practical use of maglev technology in rapid transit systems. The life cycle costs (LCC) for the maglev system

including the cost of initiating such projects are included in this survey and are evaluated. To serve the purpose, an algorithm is

presented that facilitates the technical and economical analyses of maglev systems. The proposal for a long distance maglev

system, Mashhad-Tehran (M-T), is used as a case study by using the proposed algorithm. Moreover, the cost of establishing and

operating M-T project is estimated by two other different approaches. These include the already established mathematically based

cost estimating method, and the cost estimations based on the international norms and standards. These standards are based on

statistical (or provided) data. Such cost estimations assist verification of the proposed algorithm. Comparisons between outcomes

of the three methods prove close agreement for the cost estimation by all of them. It is concluded that the proposed algorithm for

implementation and operation of maglev route is practical.


H. ZHou, L.m. Sun,
Volume 11, Issue 3 (Transaction A: Civil Engineering, September 2013)
Abstract

Damping of a full-scale cable with a pair of passive–on magnetorheological (MR) dampers was tested. A cable of 215.58m long with the first mode frequency of 0.658Hz was tensioned horizontally in cable prefabrication factory. Two MR dampers were attached to the cable in an angle in the plane perpendicularly to the cable axis in 5m length from the cable anchorage. The applied voltage level was 0V, 3V, 6V and 9V. The cable was excited manually to a certain amplitude level for the first three modes of vertical vibration. The free decay curves of the cable were then recorded. The damping of the cable was calculated from the measured anti-node vibration amplitude. The damping of the free cable was also tested for reference. It was found that the damping of the cable is still low when MR dampers were no voltage strengthened. However, the damping of the cable increased greatly for the other with MR damper cases compared to free cable. Further study showed that the damping of the cable with MR dampers were strongly depended on applied voltage level and vibration amplitude. There is an optimal damping value when MR damper is voltage strengthened. The dependence of the optimum damping on applied voltage level, vibration amplitude and vibration mode was further analyzed.
Khaled Farah, Mounir Ltifi, Tarek AbicHou, Hedi Hassis,
Volume 12, Issue 3 (Transaction B: Geotechnical Engineering, July 2014)
Abstract

The purpose of this study is to compare the results of different probabilistic methods such as the perturbation method, Stochastic Finite Element Method (SFEM) and Monte Carlo Method. These methods were used to study the convergence of direct approach for slope stability analysis and are developed for a linear soil behavior. In this study, two dimensional random fields are used and both the First Order Reliability Method (FORM) and Limited Step Length Iteration Method (LSLIM) have been adopted to evaluate the reliability index. The study found that the perturbation method of the second order is easy to apply using the field’s theory because accuracy is reached even with different coefficients of variation of input variables, while the spectral finite element method yields accurate results only for high levels of solution development.
H. Khalili Shayan, J. FarHoudi, H. Hamidifar,
Volume 13, Issue 1 (Transaction A: Civil Engineering March 2015)
Abstract

Because of the complexity of the physical processes in the vicinity of the hydraulic structures due to the separation of the flow, traditional methods for for prediction of maximum scour depth downstream of hydraulic structures are mostly based on empirical approaches. Hence, only a few theoretical works have been reported to study this phenomenon. The present paper describes a new approach based on the momentum principles to estimate the maximum local scour depth downstream of a submerged sluice gate flowing over horizontal or adverse stilling basin. A control volume of the fluid in the equilibrium state of the scour hole was considered and based on momentum principles, some equations are derived to estimate the scour depth at equilibrium state. To verify the proposed equations, large numbers of experiments were planned and conducted under wide range of characteristic parameters such as, incoming Froude number, sediment size, tailwater depth, length and slope of the apron. It was found that the proposed equations fall in a good agreement with experimental results. It was also observed that, in the case of horizontal apron, a specific tailwater depth exists with which the local scour depth attains a minimum value. However, in the case of adverse basins when the tailwater depth takes a specific value, the maximum depth of the scour hole reaches to its maximum and then decreases to a constant value as the tailwater depth increases. This critical tailwater depth was formulated using a semi-theoretical equation.
H. Liu, M. He, J. Guo, Zh. Hou, Y. Shi,
Volume 13, Issue 2 (Transaction A: Civil Engineering June 2015)
Abstract

Self-centering pier (SCP) has been viewed as a remarkable accomplishment which is able to sustain major lateral loading with reduced structure damage in seismic engineering. Stiffness deterioration observed in experiment is vital for the seismic performance of self-centering concrete pier. In this contribution, the associated stiffness deterioration with respect to the structural damage is modeled in a modified analytical model for SCP comprehensively. In the proposed modified theoretical model, the lateral force-displacement relation associated with the stiffness reducing is analyzed. Three damage factors are introduced in the stiffness deterioration analysis to illustrate the damage evolution caused by gradually increasing lateral displacement. The proposed modified quasic-static model with damage evolution or stiffness deterioration has been validated against an experiment we conducted, where a good agreement is clearly evident. Subsequently, a parametric investigation focusing on aspect ratio, initial pre-tension, and ratio of ED (Energy Dissipator) was conducted to evaluate the hysteretic behavior of SCP under quasi-statically cyclic loading.
Mr. L. Yanlong, Mr. L. SHouyi, Mr. Y. Yang, Miss T. Xing,
Volume 13, Issue 4 (Transaction A: Civil Engineering December 2015)
Abstract

This study simulates the temperature field and temperature stress of concrete face slabs, considering the cold waves that occur during construction as well as the contact friction between the face slabs and the cushion layer. The results show that when a cold wave occurs during construction, the surface and center temperature of the face slabs continually drop with the outside air temperature, with the surface temperature drop being the largest. In addition, the surface and center of face slabs are subjected to tensile stress, with the maximum principal stress on the surface being greater than that on the center. The maximum principal stress of the surface and center occurs at approximately half of the dam height. This study also examines the surface insulation of concrete face slabs. Surface insulation can significantly improve the temperature drop range and the maximum principal stress amplitude caused by the cold wave. A stronger heat preservation results in smaller tensile stress and an increase in the amplitude of face slabs.


L. Zeng, Q. ZHou, Ch. Xu, Y. Wu, X. Tu,
Volume 13, Issue 4 (Transaction A: Civil Engineering December 2015)
Abstract

To study seismic performance of concrete-encased composite columns with T-shaped steel cross-section, twelve half-scale columns were tested under quasi-stastic cyclic loading. The result indicates that concrete-encased composite columns with T-shaped steel section possess good seismic performance. The failure modes include bending failure, shear-bond failure, shear compression failure and shear-composition failure. Unsymmetrical phenomenon of positive and negative hysteresis loop was shown evidently. Span ratio has a great influence on failure mode. The ductility performance decreases with increasing of axial compression level. As stirrup ratio increases, ductility and bearing capacity of columns are improved greatly, and energy dissipation capacity after yielding is enhanced. Cross tie can enhance ultimate bearing capacity, and lower strength attenuation and stiffness degradation on the later loading stage


Adel Djellali, Abdelkader Houam, Behrooz Saghafi, Ali Hamdane, Zied Benghazi,
Volume 15, Issue 3 (Transaction B: Geotechnical Engineering 2017)
Abstract

To study and predict the behavior of flexible pavement over expansive soils, a pavement structure was subjected to different laboratory and fieldwork experiments. The existing pavement was replaced and designed based on California Bearing Ratio (CBR) method, with a new one, and subjected to the traffic from various number of load cycles from 12.1 up to 155.52 kcycles of standard axle load (80 kN) through dual wheel assembly over a 6-month period. As the preliminary step, the deflection measurements were taken at the asphalt surface layer, using a Total station at different distances as function of truckload applications. The numerical analysis is carried out with the Finite Element software package PLAXIS version 2012. In the new model, the calculation of the transferred pressure to the pavement through contact area of tires is 3D it was turned into a 2D problem, and the pavement was subjected to a static loading using a ratio factor of dynamic additional charge. The materials’ behavior was simulated with nonlinear models: Mohr–Coulomb (MC) for pavement layers and soft-soil model (SSM) for the expansive subgrade, in saturated drained and undrained conditions. The results indicate that displacements under static loading in saturated drained conditions and when non-linear materials are present are the closest to field measured deflections.


Younes Aminpour, Javad FarHoudi,
Volume 15, Issue 5 (Transaction A: Civil Engineering 2017)
Abstract

Local scour downstream of hydraulic structures is one of the critical phenomena which has absorbed a vast amount of interests by researchers. The designers of hydraulic structures, particularly, spillways try to utilize proper means to minimize the consequences of excess energies downstream of such structures which usually tend the erosion at their immediate downstream reaches. The stepped spillway is designed to create a large amount of energy dissipation by means of steps and would decrease the amount of scour evolution at its downstream. This article presents the results of 67 experiments conducted at two different scales of stepped spillways, to study the local scour downstream the structure. The experiments were planned to consider a wide range of geometrical factors, flow characteristics, and sediment properties. The time length of experiments was ranged from 6 to 24 hours which produced more than 80000 data points for analytical considerations. The results were used to render a regression equation to define the similarity among the scour hole profiles. It was observed that, a long term observation would be needed to reach the equilibrium state. However, semi-equilibrium conditions will be achieved after 24 hours. It was also noted that the depth of scour hole adjacent to channel walls was bigger than that at centerline. 



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