International Journal of Civil Engineering 1735-0522 2283-3874 2 4 2004 12 1 Numerical Simulation of Breaking Waves by a Vof-Type numerical Model 201 212 EN A. Khayyer N A. Yeganeh Bakhtiari Y A. Ghaheri N T. Asano N A two-dimensional numerical model has been developed to study wave breaking on a sloping beach. The basic elements of numerical model are Reynolds Averaged Navier-Stokes (RANS) equations that describe the mean flow motion of a turbulent flow a k turbulence closure model that describes the turbulent transport and dissipation process an efficient technique (VOF- Volume Of Fluid method) for tracking the free surface motion and a new scheme developed by Lin and Liu (1999) for wave generation. Shoaling, breaking and overturning of solitary wave on a slope of 1/16 have been studied with the main emphasis on turbulence characteristics. Turbulence characteristics i.e., turbulence kinetic energy, k turbulence dissipation rate, turbulence production, pr turbulence eddy viscosity, vt and their spatial distribution during the breaking process have been discussed in great details. Spatial distribution of turbulence characteristics and the order of magnitude have been found to be in agreement with existing experimental and numerical studies. The main characteristic of plunging breaking waves, the shoreward advective transport of turbulence, has also been investigated and numerically proved. BREAKING WAVES, SOLITARY WAVES, PLUNGING BREAKING, VOLUME OF FLUID (VOF) METHOD, INTERNAL WAVE-MAKER, TTURBULENCE CHARACTERISTIC http://ijce.iust.ac.ir/article-1-1065-en.html

International Journal of Civil Engineering 1735-0522 2283-3874 2 4 2004 12 1 SYSTEM DYNAMICS MODELING APPROACH FOR GATED AND UNGATED FLOOD ROUTING IN A CASCADE MULTI-RESERVOIRS SYSTEM 213 222 EN JALALI M.R. Y AFSHAR A. N Mokhtare A.R. N It is indispensable to explore simulation techniques that not only represent complexdynamic systems in a realistic way but also allow the involvement of end users in modeldevelopment to increase their confidence in the modeling process. System dynamics as a feedbackbasedand object-oriented simulation approach is presented for reservoir operation modeling. Thequick modeling process, the trust developed in the model due to user contribution, group modelsdevelopment possibility and the effective relations of model results are the most significant strongpoints of this approach. The simple modification of model in response to changes in system andcapability to accomplish sensitivity analysis make this approach more attractive and useful ratherthan traditional reservoir operation models. In this paper system dynamics is applied to simulateoperation of a free reservoir with an Ogee spillway, a reservoir with a gated spillway and finally amulti-reservoir system with simple and gated spillways. The multi-reservoir system on Karun riverin south of Iran is modeled under flood condition as a case study in order to demonstrate thecapabilities of the developed model. http://ijce.iust.ac.ir/article-1-28-en.html

International Journal of Civil Engineering 1735-0522 2283-3874 2 4 2004 12 1 PARAMETRIC STUDY OF KISH CARBONATE SAND UNDER TRIAXIAL SHEARING 223 231 EN SALEH ZADEH H. Y Ghazanfari e. N To study the behavior of carbonate sands parametrically, some monotonic triaxial testswere carried out on Kish carbonate sand. The sample was provided from Kish Island beach. Inorder to examine the effect of density and confining pressure, samples in loose and dense stateswere tested under different confining pressures. For studying the effect of drainage andconsolidation, different stress paths were followed. Also to study the effect of particle crushing indrained tests all samples were graded before and after testing. Comparison between loose anddense samples in both drained and undrained tests showed that with increasing confiningpressure, the reduction in shear resistance in loose samples is less than dense samples and theincrement rate of particle crushing in loose samples is more than dense samples. In the range oflow confining pressures both loose and dense samples showed dilation response. With increasingconfining pressure, the loose samples tended to exhibit contraction and the rate of dilation indense samples reduced. Because recovering undisturbed sample of carbonate sediments is veryhard or even impossible so the effect of soil disturbance is not studied in this research. Confining pressure, Contraction, Deviator stress, Dilation, Interlocking, Particle crushing, Stress path http://ijce.iust.ac.ir/article-1-32-en.html

International Journal of Civil Engineering 1735-0522 2283-3874 2 4 2004 12 1 LIQUEFACTION-INDUCED LATERAL SPREADING- AN OVERVIEW AND NUMERICAL ANALYSIS 232 245 EN SOROUSH A. Y Koohi sh. N Lateral spreading of liquefied saturated sandy deposits happens during and shortly afterearthquakes. This paper first reviews this phenomenon by means of reviewing and comparingobservations on case histories and experimental works. Based on the results from the review andcomparison, a mechanism for describing lateral spreading will be suggested. The Finn model,adopted in the Computer code FLAC is employed to carry out numerical analyses of lateralspreading of the Wildlife Site, happened during the 1987 Superstition Hills earthquake. First themodel is calibrated by means of numerical analysis of the first centrifuge model test of theVELACS Project. For the Wildlife site, three types of analysis are carried out: a) coupledliquefaction-consolidation analysis using the coefficient of permeability (K1) of the liquefiedlayers, as reported in the literature b) analysis type (a), but with K equal to 0.1K1, and c) a fullyundrained liquefaction analysis. The analyses results, in forms of excess pore water pressures andsurface displacements, indicated that the fully undrained behavior of the liquefied layers betterrepresents the behavior and response of the site during the earthquake. http://ijce.iust.ac.ir/article-1-33-en.html

International Journal of Civil Engineering 1735-0522 2283-3874 2 4 2004 12 1 A PARAMETRIC INVESTIGATION ON STIFFENING AXIALLY LOADED PANELS 246 256 EN M.M. Alinia m.alinia@aut.ac.ir Y 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. Plate buckling; Axial loading; Stiffener; Optimization http://ijce.iust.ac.ir/article-1-587-en.html

International Journal of Civil Engineering 1735-0522 2283-3874 2 4 2004 12 1 RELIABILITY OF NONLINEAR STATIC METHOD IN SEISMIC PERFORMANCE PREDICTION OF REINFORCED CONCRETE FRAMES WITH MEDIUM DUCTILITY 257 267 EN GHODRATI AMIRI G. Y SEDIGHI S. N In the past decade design procedure changed to �performance-based design� from�force-based design�, by this mean many researchers focused on nonlinear static analysis (NSA)and the procedure named �PUSHOVER�. Advantages of this method are defining the inelasticbehavior of structure without nonlinear dynamic analysis (NDA) effort and also defining plastichinges formation in critical elements, and the order of formed plastic hinges. In spite of these goodadvantages NSA is limited to short and planar structures and application of that in tall andtorsionaly asymmetric structures may yield unreliable results.In this study reliability of NSA is investigated by performing both nonlinear static and dynamicanalysis on six 2D moment resisting concrete frames. Non linear dynamic analysis has been doneby the suggested method in FEMA356 guideline called �Target Displacement Method�. A groupof 4 different lateral increasing loads were used in pushover analysis and 3 different groundmotions were applied in NDA. Results indicate that same responses can be obtained by performingNSA, but errors will be increased by frames height increment. Nonlinear Static Analysis, Pushover, Lateral increasing load, Reinforced concrete frame and intermediate ductility http://ijce.iust.ac.ir/article-1-30-en.html