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Investigating the Effects of Specimen Size and Dimensions Ratio on Compressive Strength of Concrete
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Tagi (Supervisor)
Abstract
Concrete is one of the most widely used building materials. Compressive strength of concrete is the most important property in designing reinforced concrete structures. Compressive strength test should be carried out on specimens with standard dimensions. In practice, dimensions of structural elements could be different from the dimensions of standard specimen. The dimensions’ ratio influences the strength of concrete specimen and the coefficient of strength variation. In the present study it is tried to obtain a meaningful relationship between size and strength based on the results of the tests on the specimens with different dimension ratios. Specimens examined in this study are C25 grade...
Effects of moisture on warm mix asphalt containing Sasobit
, Article Scientia Iranica ; Volume 24, Issue 4 , 2017 , Pages 1866-1873 ; 10263098 (ISSN) ; Naderi, B ; Tabatabaee, N ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
The asphalt industry has been at the forefront of sustainable development. Warm Mix Asphalt (WMA) has been developed to cope with issues such as high energy prices and air pollution. These mixes require less energy and generate fewer pollutants during production in comparison with conventional Hot Mix Asphalt (HMA). Although a promising technology, the durability of WMA is not clear because long-term WMA field performance data is limited. This study investigated the susceptibility of Sasobit-modified WMA to moisture, since moisture damage is a major cause of premature pavement failure in asphalt concrete. To this end, WMA samples were made using different concentrations of Sasobit and the...
Seismic Response of Zipper Inverted-V Braced Frame with Unequal Buckling-Restrained Braces
, M.Sc. Thesis Sharif University of Technology ; Ahmadizadeh, Mehdi (Supervisor)
Abstract
This study presents the advantages of using unsymmetrical buckling restrained braces in zipper frames for simultaneous improvement of peak and residual response of low- and mid-rise buildings. It is demonstrated that such combination allows for the usage of benefits of each of these systems, namely the significant energy dissipation capacity of buckling restrained braces and better distribution of hysteretic energy dissipation demands through the elevation observed in zipper frames. It has already been shown that using buckling restrained braces of varying yield strengths within each story of a building can improve the residual response of buckling-restrained-braced frames without severely...
Assessment of offshore platforms under extreme waves by probabilistic incremental wave analysis
, Article Journal of Constructional Steel Research ; Volume 67, Issue 5 , 2011 , Pages 759-769 ; 0143974X (ISSN) ; Ebrahimian, H ; Bagheri, V ; Holmas, T ; Sharif University of Technology
2011
Abstract
In this study, a novel probabilistic framework named Probabilistic Incremental Wave Analysis (PIWA) is established in order to assess the performance of jacket offshore platforms under extreme waves. The PIWA can take into account the uncertainties in three main elements consisting of sea state parameters, structural response and collapse capacity. The main advantage of the PIWA approach is reflected in decoupling of the wave hazard and structural analyses via an intermediate variable known as the wave height intensity measure. Despite the fact that most of the uncertainties associated with structural response are concentrated in wave hazard, this will enable the PIWA to estimate the...
Equivalent linear model for existing soil-structure systems
, Article International Journal of Structural Stability and Dynamics ; Volume 16, Issue 2 , 2016 ; 02194554 (ISSN) ; Ghannad, M. A ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
Abstract
The concept of equivalent linearization is extended for the soil-structure systems, in which the strength ratio (defined as the ratio of the yielding strength to the elastic strength demand) is known rather than the ductility ratio. The nonlinear soil-structure system is replaced by a linear single-degree-of-freedom (SDOF) system, which can capture the response of the actual system with sufficient accuracy. The dynamic characteristics of the equivalent linear SDOF system are determined through a statistical approach. The super-structure is modeled by an inelastic SDOF system with bilinear behavior, and the homogeneous half space beneath the structure by a discrete model, following the Cone...
Strengthening design limitations of an RC frames using FRP column wrapping considering column-to-beam strength ratio
, Article Scientia Iranica ; Volume 14, Issue 5 , 2007 , Pages 405-413 ; 10263098 (ISSN) ; Esmaili, A ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
The aim of this paper is to study the influence of the column-to-beam strength ratio on the seismic strengthening of a column with a Fiber-Reinforced Plastic (FRP) wrapping system. FRP wrapped Reinforced Concrete (RC) columns are analyzed to obtain moment-curvature curves using FRP confined concrete characteristics. A pushover analysis of a 2D model was performed on one and three-story moment-resisting frames, with different column-to-beam strength ratios. The results indicate that FRP strengthening is more efficient in frames with a low ratio of column-to-beam strength, due to the type of lateral failure mechanism of the frame. Also, high values of the column-to-beam strength ratio can be...
Effect of martensite volume fraction on work hardening behavior of triple phase (TP) steels
, Article Materials Science and Engineering A ; Volume 528, Issue 13-14 , 2011 , Pages 4422-4426 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
The strain hardening behavior of AISI 4340 steel with dual phase (DP) and triple phase (TP) microstructures with constant ferrite volume fractions of 34% was investigated. The microstructures of specimens were analyzed using an optical microscope. The tensile flow behavior of all the samples was explained using Holloman equation. Results showed that in both DP and TP steels, work hardening takes place in two stages. The onset strain of second stage of work hardening and Holloman equation parameters (work hardening exponent and strength coefficient) in both stages were increased with the increase of martensite volume fraction in TP steels. At first stage of work hardening, ferrite phase...
An experimental study on mechanical behavior of a calcite cemented gravelly sand
, Article Geotechnical Testing Journal ; Volume 41, Issue 3 , May , 2018 , Pages 494-507 ; 01496115 (ISSN) ; Haeri, S. M ; Shahrabi, M. M ; Khosravi, A ; Sajadi, A. A ; Sharif University of Technology
ASTM International
2018
Abstract
In the study presented herein, a simple method for laboratory calcite cementation of a reconstituted gravelly sand was presented. This method was used to prepare cemented gravelly sand specimens, which have similar natural characteristics to alluvial deposit of the city of Tehran. The formation and distribution of calcite bonds, as well as the effectiveness of the presented calcite cementation method in increasing interparticle cohesion, as observed in weakly to moderately cemented soil in Tehran, were evaluated by means of chemical analysis, X-ray diffraction technique, and unconfined compressive strength tests. The cementation technique was used to prepare triaxial specimens with calcite...
Sensitivity analysis of jacket-type offshore platforms under extreme waves
, Article Journal of Constructional Steel Research ; Volume 83 , 2013 , Pages 147-155 ; 0143974X (ISSN) ; Bahaari, M. R ; Bagheri, V ; Ebrahimian, H ; Sharif University of Technology
2013
Abstract
Jacket-type offshore platforms play an important role in oil and gas industries in shallow and intermediate water depths such as Persian Gulf region. Such important structures need accurate considerations in analysis, design and assessment procedures. In this paper, nonlinear response of jacket-type platforms against extreme waves is examined utilizing sensitivity analyses. Results of this paper can reduce the number of random variables and consequently the computational effort in reliability analysis of jacket platforms, noticeably. Effects of foundation modeling have been neglected in majority of researches on the response of jacket platforms against wave loads. As nonlinear response of...