1 Tarbiat Modares University 9638 Creep of Rock Fill Material in Large Scale Odometer with Considering Particle Breakage in Loss Angeles Test Komakpanah1 Ali AghaMajidi2 Mohammad 1 6 2010 10 1 0 0 06 07 2004 07 11 2006 Abstract Creep is a time-dependent deformation of soil under constant effective stresses. For investigation on the creep of rock fill materials, 3 samples from 3 dams of Iran that are already under construction were selected. Normal effective stresses were applied on the specimens with a large-scale odometer apparatus that is specially designed for the research. Comparison of creep rate, amount of particle breakage and results of Los Angeles test shows a relationship between these three parameters. Consequently Los Angeles test that is a simple and accessible test, can give a prediction and estimation of behavior and properties of rock fill materials. Based on the test results, an approximate relationship could be found between creep, particle breakage and Los Angeles test results.
4301 Analytical Behavior of Brick-Infilled Concrete Frames Strengthen by FRP Nateghi. F. Dehghani A. 1 6 2010 10 1 0 0 06 06 2007 04 04 2008 Abstract Due to various deficiencies, inadequate lateral stiffness, weak design and weak construction, many reinforced concrete buildings are highly damaged during the major earthquakes. One way to retrofit these buildings is to improve the behavior and to prevent the total collapse of the reinforce masonry infilled walls in order to make them behave such as structural walls with composite materials. In this study, the concept of equivalent strut is investigated by finite element modeling and behavior of the compression strut and tension tie is presented to model unretrofit and retrofit masonry infilled walls. Analytical pushover results show great accordance with experimental results. 4297 3D Numerical Analysis of Bed Topography in 180 Degree Channel Bend Mansoori A. R. Salehi Neyshabouri S. A. A. Honarbakhsh A. 1 6 2010 10 1 0 0 07 11 2006 05 06 2008 Abstract The complex three-dimensional flow characteristics in river bends necessitates the use of a three-dimensional numerical model. The numerical model used in this paper is called SSIIM (Sediment Simulation In Intakes with Multiblock option).The 3D model already has showed satisfactory results in related applications. In this study, SSIIM is applied to study the variation of channel bed under steady flows in a 180 mild curved open-channel with sandy bed. Bed roughness was calibrated to ks 4.5 d90 6.25d50 . Comparison of results showed good agreement between the computed and measured bed topography. The model simulated both the point bars near the inner bank and the scour holes near the outer bank. In addition, the positions of these phenomena are in fair agreement with the measured data. Numerical results show some dependencies on the grid size. In addition, deviations of model from the experimental data as well as uncertainties in numerical modeling are discussed. 7587 ‹‹Research Note›› Determination of Strengths of Construction Materials Applying the in Situ Twist off Method Naderi M. Maadani S. 1 6 2010 10 1 0 0 06 01 2007 06 11 2008 Abstract Since for some reasons such as studying the behaviour of old construction materials and proper replacement of the deteriorated sections, adequate knowledge about the true in situ strength of the construction materials has become a necessity, many attempts have been made to invent and develop new in situ methods in recent years. Most of these methods measure the in situ strengths of materials indirectly by measuring properties other than the strength and relating them to strength by some defined relationships. This paper introduces an innovative partially destructive method, called “Twist-off”, for the assessment of in situ concrete, mortar, and masonry strengths of materials used in buildings and structures. In addition to the laboratory results, the results of the successful application of this method on site are also presented in this paper. Based on the results obtained, the use of this new in situ method with its advantages of simplicity (no need for experts), low expense, cheap and simple apparatus, little damage to the surface area, and high accuracy is strongly recommended for the determination of in situ strengths of construction materials (concrete, mortar, and masonry) used in different buildings and structures. 5193 Research Note›› Determination of Active Earth Pressure for Reinforced Retaining Walls in c-) Soils Ghanbari A. Shekarian S. 2 1 6 2010 10 1 0 0 07 12 2006 06 11 2008 Abstract The prediction of active earth pressures is essential to the design of retaining walls in case of reinforced and unreinforced soils. In this study, a new analytical method is presented to determine the coefficient of earth pressure. The horizontal slice method is used to compute the active earth pressure behind a rigid retaining wall in consideration of the granular soils. To verify the correctness of the suggested method, its results were compared with those of existing studies. Results show that the developed formulation for non-cohesive soils has a good agreement with the results of software simulations. Also, a new formulation for cohesive soils was presented and its results were compared with the Rankine method. The effect of parameters such as the cohesion of soil mass, the angle of internal friction and the angle of wall friction were assessed. In all cases, it is shown that the horizontal slice method has good capability to predict the active earth pressure. 6822 Effect of Random Initial Crookedness of Members on Reliability of Steel Frames Lotfollahi-Yaghin M. A. Negin M. 1 6 2010 10 1 0 0 07 03 2007 04 02 2009 Abstract In this paper the effect of two types of common initial geometric imperfections on the reliability of steel frames is investigated. These imperfections are the coordinates of connection nodes and crookedness of members. Most finite element reliability analyses in past literature neglect this source of uncertainty. For this purpose static nonlinear pushover structural analysis is used from which reliabilities are estimated based on FORM and Monte Carlo sampling methods. Furthermore to investigate the importance of uncertain parameters, reliability sensitivity analysis is performed by use of the direct differentiation method which has been implemented in the object oriented software framework Open Sees. It is demonstrated that some of these geometric imperfections have significant influence on reliability assessment of steel frames. 5115 Shear Strength Degradation of Circle Reinforced Concrete Columns Barghi1* M. Lagzian A 1 6 2010 10 1 0 0 06 06 2007 04 02 2009 Abstract Earthquake reconnaissance has identified shear failure of reinforced concrete columns as a primary cause of failure of older existing reinforced concrete columns. Satisfactory seismic response of reinforced concrete columns requires that brittle failure modes be inhibited. In this research, different factors which affect the shear failure of columns have been studied, and then by using the results of 103 cyclic loading tests on columns, a new model for estimation of shear strength degradation under cyclic loading has been developed. The proposed model can be used to estimate shear strength degradation of reinforced concrete columns with shear, shear flexural and flexural failure separately. Uncertainty of the results of this model is little because the study has been concentrated on the three independent groups of the columns with one specified failure mode. The results of cyclic loading tests used in this study have been taken from the PEER ( Pacific Earthquake Engineering Research Center) database. 384 Evaluation of Genetic Algorithms for Optimal Design of Cascade Stilling Basins .Afshar M.H Daraeikhah M. 1 6 2010 10 1 0 0 07 12 2007 06 03 2009 Abstracts This paper presents how the genetic algorithm (GA) can be applied to design of cascade stilling basins. Genetic Algorithm is adaptive method, which can be used to solve search and optimization problems over a period of generations, based upon the principles of natural selection and survival of the fittest ones. The objective of this research is to minimize total cost of construction effectively which is a function of height of falls and length of stilling basins, while fulfilling the hydraulic and topographical criteria. The efficiency of GA discussed here has been tested for a benchmark example and the result for this algorithm is compared with the other method introduced by Vittal and Porey. The results clearly reveal superiority of the GA algorithm 8072 Evaluation and Comparison of Real, Artificial and Pulse-Like Models Near-Fault Earthquakes SHAKIB H. Hashemi 2* S.SH 1 6 2010 10 1 0 0 07 08 2006 06 05 2009 Abstract Ground motions close to a ruptured fault can be significantly different from those further away from the seismic source. In the other hand there are a few real records which include the characteristic of near-fault records. Hence, simulation of these records is useful in order to study their effects on the behavior of structures which has been built near the faults. Tehran is a city in the neighboring of several active faults but there aren’t any nearfault real records in this place. In this paper, according to mechanism and situation of North Tehran Fault (NTF), seven near-fault real records with forward directivity have been selected and by using selected records a pulselike decaying sinusoidal model has been proposed as NTF simulated near-fault records. Finite fault method with specific considerations has been used as a suitable and reliable method for creating near-fault artificial record and the artificial records for NTF has been generated at 2, 5 and 10 km distances. Finally the results for real and artificial records and also the pulse-like model have been compared together. 3473 Seismic Evaluation of Concrete Moment Frames with Low Height Beams KHEIRODIN A. FAMILY S. 1 6 2010 10 1 0 0 06 05 2007 07 08 2009 Abstract Low height beams in concrete moment frames, decrease the ability of beams in controlling lateral displacement of buildings. Because of that, in the sixth subject from Iranian Regulations of Buildings and its following, in the 3rd edition of Standard 2800, the height of buildings with low height beams has been limited to 3 floors or 10 meters. According to that, in this study, concrete buildings with different amount of stories and moment frames, with medium ductility and the height of beams in 30 centimeters, have been analyzed (with linear equivalent static and spectral dynamic analysis Methods)and designed on the basis of seismic principles in the 2nd and 3rd edition of Standard 2800. Finally, studies continued with nonlinear static analysis and the performance point of structures determined (with capacity spectrum and displacement coefficient methods) in 4 levels of different seismic risks. Studies show that only one or two story buildings that designed with 2nd edition of Standard 2800 have enough safety in design base earthquake level (DBE) and also higher buildings, should go under rehabilitation.