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Home>Products>Journal and Reviews>I.RE.C.E.>Latest issue
International Review of Civil Engineering - March 2010 - Papers
International Review of Civil Engineering - Papers
by Lazarus Teneketzis Tenek Vol. 1. n. 1, pp. 1-7
Abstract - The present article presents a derivation of the Laplace differential equation for electrostatics and potential flow problems using fundamental principles of fluid mechanics. Using the incremental symbol d subsequently derives difference formulas for the first and second derivatives and states the Laplace equation in a discretized form over points of a finite difference grid. A linear system of equations is formed and potential as well as velocity are applied as boundary conditions. The solution provides the potential function in each point and subsequently the currents and velocities in two-dimensions. Using other equations of fluid mechanics, we estimate at each point of the grid also the pressure and the temperature. Applications include, potential flow in a domain with a nearly central plate and fluid flow over a flat plate. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fluid Mechanics, Potential Flow, Laplace Equation, Electrostatics, Potential Function, Finite Difference Method.
Vol. 1. n. 1, pp. 8-17
Abstract - During the motion of the forklift machine or keeping the goods on the pallet rack structures, there is possibility of hitting forklift to the structural component of the rack structures. Generally this load act as impact load on the upright of the rack structures. Thus this load creates additional stress in the uprights other than stresses due to load of the goods. This paper describes the three dimensional finite element modeling and impact analysis of 3-D semi-rigid frame of conventional pallet racking system. In this study three dimensional model of semi-rigid frames were prepared using the finite element program ANSYS and transient dynamic analysis was carried out for 9 different types of developed upright sections. Basic objective of the study is to optimize the upright section when subjected to the impact of the forklift machine. The reductions in stresses for 2.5mm thick section with comparison to 2 mm thick section have been found to be 30 – 36%. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Transient Dynamic Analysis, Cold Formed Steel, Semi- Rigid Connections.
Vol. 1. n. 1, pp. 18-31
Abstract - In this paper, an improved model for the static analysis of reinforced concrete plates stiffened by arbitrarily placed parallel reinforced concrete or steel beams with deformable connection taking into account the influence of creep and shrinkage effects relative with the time of the casting and the time of the loading of the plate and the beams is presented. According to the proposed model, the stiffening beams are isolated from the plate by sections in the lower outer surface of the plate, making the hypothesis that the plate and the beams can slip in all directions of the connection without separation (i.e. uplift neglected) and taking into account the arising tractions in all directions at the fictitious interfaces. These tractions are integrated with respect to each half of the interface width resulting two interface lines, along which the loading of the beams as well as the additional loading of the plate is defined. Their unknown distribution is established by applying continuity conditions in all directions at the interfaces taking into account their relation with the interface slip through the shear connector stiffness. The utilization of two interface lines for each beam enables the nonuniform distribution of the interface transverse shear forces and the nonuniform torsional response of the beams to be taken into account describing better in this way the actual response of the plate - beams system. The analysis of both the plate and the beams is accomplished on their deformed shape taking into account second-order effects. Six boundary value problems are formulated and solved using the Analog Equation Method (AEM), a BEM based method. The solution of the aforementioned plate and beam problems, which are nonlinearly coupled, is achieved using iterative numerical methods. The adopted model describes better the actual response of the plate - beams system and permits the evaluation of the shear forces at the interfaces in both directions, the knowledge of which is very important in the design of prefabricated ribbed plates. The evaluated lateral deflections of the plate - beams system are found to exhibit considerable discrepancy from those of other models, which neglect inplane and axial forces and deformations. Numerical examples with great practical interest are presented. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Bending, Ribbed Plate, Boundary Element Method, Creep, Elastic Stiffened Plate, Reinforced Plate With Beams, Shrinkage, Slab-And-Beam Structure.
Vol. 1. n. 1, pp. 32-38
Abstract - This paper presents the results of laboratory model tests for studying the improvement of soft clay layer by using both partial replaced sand columns with/without confinement. This research is performed to study the effect of sand column to improve the bearing capacity, control the settlement, the variation of sub grade modulus, and investigate the induced failure mechanism of shallow circular footing on replaced soil with/without skirts. The results show that the improvement of load bearing capacity could be remarkably induced, using both partial replaced sand column with and without confinement by skirts. The adopted technique can substantially modify the stress displacement curve and significantly decreases the settlement. In addition, it makes the replaced soil block inside the skirts behaves as deep foundation. Therefore, the mechanism of the bearing capacity failure of a footing rested on soft clay can be modified from punching to general bearing capacity failure at the tip of confined replaced sand column. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Soil improvement, bearing capacity, Circular Footing, Soft clay, Confinement, Skirts.
Vol. 1. n. 1, pp. 39-53
Abstract - This paper investigates the use of textured interface, in the form of expanded metal sheets, to improve the static strength and fatigue performance of steel-concrete-steel (SCS) sandwich beams. Push-out tests are performed to evaluate the effectiveness of the textured interface to resist shear and to reduce slip between the face plates and the concrete core. Flexural tests are carried out on SCS sandwich beams to evaluate their load-displacement behavior and ultimate strength. The combined use of mechanical shear connectors and texture interface bond and their load sharing mechanisms are investigated. Additional tests are carried out to study the influence of textured interface on the overall fatigue performance of sandwich beams under varying load magnitude and load range. Fatigue design equation taking into account both stress range and maximum applied stress is proposed for beams with either plain or textured interface. The paper concludes that the use of textured interface improves the bond and increases the static and fatigue life of composite sandwich beams compared to those with only mechanical shear connectors. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Bond, Composite, Fatigue, Hooked Connector, Sandwich, Steel-Concrete-Steel, Textured Interface.
Vol. 1. n. 1, pp. 54-67
Abstract - A methodology is presented for modelling the inelastic torsional response of buildings in nonlinear static (pushover) analysis, and is evaluated against the results of inelastic dynamic time history analysis. A spectral modal pushover analysis is performed using spectral load vectors defined from elastic analysis, while the dynamic characteristics of an equivalent single mass system, which incorporates both translational and torsional modes, are derived using an extension of earlier methods based on the SDOF approach. The suggested method is verified for the case of single-storey monosymmetric buildings using unidirectional, as well as bidirectional excitation, under various strong motion records. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inelastic Torsion, Pushover Analysis, Nonlinear Response, Equivalent SDOF Systems.
Vol. 1. n. 1, pp. 68-77
Abstract -
During dynamic events such as impact and blast loading, structures
experience high rates of loading and the materials experience elevated
strain-rates. During such events, a large amount of energy is also
suddenly imparted to the structure. If the structure fails to absorb the
incoming energy, a sudden, catastrophic collapse may occur. In spite of
our continued efforts to understand the impact resistance of reinforced
concrete elements, our comprehension in this area remains severely
limited. There also remains a critical need to devise techniques of
strengthening structures under impact loading. Impact tests were carried
out on simply supported reinforced concrete beams using a fully
instrumented drop-weight impact machine. The drop height was varied to
change the rate of loading, and companion tests were carried out at
slow, quasi-static rates of loading. The effectiveness of externally
bonded fiber reinforced polymers (FRP) sheets in enhancing the impact
resistance of reinforced concrete beams was also investigated. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Impact Loading, Reinforced Concrete Beams, Strengthening, Fiber Reinforced Polymer, Bond, Energy Absorption.
Vol. 1. n. 1, pp. 78-82
Abstract - In
the present paper mortars with air lime and hydraulic binders (natural
pozzolan and white cement) were manufactured using standard sand and
different water-binder ratios (w/b). The influence of the w/b ratio on
the open porosity and pore size distribution as well as on compressive
strength at the age of three months was recorded. It seems that the
pores that were mainly affected by high w/b ratio were different in
different binding systems. In air lime mortars, pores with diameter
larger than 500μm and those of 1-100μm are affected while in mortars
with hydraulic binders pores of 100-500μm and 0.1-100μm are affected.
Micro pores with diameter less than 0.1μm seem to be unaffected in all
binding systems tested. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Compressive Strength, Lime-Based Mortars, Porosity, Water-Binder Ratio.
Vol. 1. n. 1, pp. 83-91
Abstract - A review of Shape Memory alloy characteristics and constitutive laws for describing the stress-strain behavior and its future possible extension of researches is presented. First, an overview of SMA characteristics is presented. The modeling aspect of SMA stress-strain relationship is discussed. Three commonly used representative constitutive models predicting quasistatic SMA behavior – Tanaka, Liang and Rogers and Brinson are examined and a comparative study is presented. Differences between the definitions of material constants in these models are pointed out. The necessity for incorporating the strain rate and non-isothermal effects in these models is discussed. In addition to the detailed review of the three constitutive laws the Brinson model is verified through a corresponding algorithm. It is shown that the model can simulate both the stress and temperature induced martensite transformation. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Smart Structures, Shape Memory Alloy, Solid-Solid Phase Transformation, Austenite, Martensite, Martensite Fraction, Twinned Martensite, Detwinned Martensite, Hysteresis Loop.
Vol. 1. n. 1, pp. 92-99
Abstract - The paper presents a study on the flexural fatigue behaviour of Hybrid Fibre Reinforced Concrete (HyFRC) containing different proportions of steel and polypropylene fibres. An experimental programme was planned to obtain the flexural fatigue lives of HyFRC, in which approximately 130 beam specimens of size 100 x 100 x 500 mm were tested under four point flexural fatigue loading. The specimens incorporated different combinations of steel and polypropylene fibres in ratio of 25-75%, 50-50% and 75%-25% by volume at a total fibre volume fraction of 1.0%. Approximately 72 static flexural tests were also conducted to facilitate the fatigue testing. The flexural fatigue life distributions of HyFRC at a given stress level is shown to approximately follow the two parameter Weibull distribution and the parameters of the Weibull distribution have been obtained. The addition of polypropylene fibres to the concrete mix results in reduction in the variability in the distribution of fatigue life of HyFRC. The mean and design fatigue lives for HyFRC containing different proportions of steel and polypropylene fibres have been estimated and compared with those of Steel Fibre Reinforced Concrete (SFRC). It has also been observed that HyFRC with fibre mix proportion of 50% steel fibres + 50% polypropylene fibres exhibits the highest mean and design fatigue lives. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fatigue Life, Hybrid Fibre Reinforced Concrete, Mean Fatigue Life, Design Fatigue Life.
Vol. 1. n. 1, pp. 100-109
Abstract - The decision-making in the evaluation of roads has been carried out according with different approaches. At first it was evaluated using two single criteria, generally the economic and temporary aspects. However, in the past few years, the multiple criteria evaluation models are staring to be implemented. This article presents a methodology based on the value analysis used for the evaluation of roads (planning stage). A model of evaluation is developed in order to obtain a value rate that can integrate all the aspects to be developed, evaluating all alternatives between 0 and 1. The relative valuation between pairs is carried out by means of a hierarchic process. In order to validate the methodology, the cross-section of two alternatives will be evaluated. One alternative is based on prefabricated elements whereas the other refers to traditional asphalt solution. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: AHP, Criteria, Decision-Making, Evaluation, Highway, Life-Cycle, Model, Planning Stage, Value Rate.
by Semion Zhutovsky, Konstantin Kovler Vol. 1. n. 1, pp. 110-118
Abstract - Chemical shrinkage is important property of cementitious materials. It is considered the main cause of autogenous shrinkage of high-strength / high-performance concretes, which are made at low water/cement (w/c) ratio. It is generally assumed that chemical shrinkage varies directly as the degree of hydration and is independent of w/c, since it has its origin in the hydration reaction stoichiometry. The methods of measurements of chemical shrinkage, which include dilatometry, pycnometry and gravimetry (buoyancy), are briefly reviewed. The interpretation of the experimental data on chemical shrinkage of hydrating cement paste is revised in the paper. The chemical shrinkage of cement pastes with w/c ratios of 0.45, 0.33, 0.25 and 0.21 was tested by gravimetry method. The degree of hydration of the pastes was determined by thermogravimetric analyzer (TGA). The effect of water/cement ratio on chemical shrinkage of hydrating cement pastes cured in saturated and sealed conditions was established and compared with the literature data. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Portland Cement, Le Chatelier, Chemical Shrinkage, Autogenous Shrinkage, Hydration.
by D. D. Ganji, M. Gorji-Bandpy, M. Mostofi Vol. 1. n. 1, pp. 119-123
Abstract - In this paper, we study an analytical solution for the Pollution Distribution in lakes. The Homotopy Perturbation Method (HPM) is used to solve this problem which describes the distribution of the pollution in lakes. In this paper, two different forms of pollution have been simulated and compared with the numerical solution and Adomian Decomposition Method which are available in the literature. Unlike the various numerical techniques, which are usually valid for a limited time interval, the solution of the presented equation is analytical and applicable for all time intervals. Also, the results presented here indicate that the method is reliable, accurate and converges rapidly. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Homotopy Perturbation Method (HPM), Pollution, System of Lakes, System of ODEs. |
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