Sharif Digital Repository

The layout problem is directly related to the material handling system; therefore, these two concepts are always being considered together. The main criterion for evaluating the layout in the objective function, is the cost of controlling and moving the materials. In order to calculate the material handling cost, it is necessary to provide an accurate information on the distance between departments, number of goods transported, and the cost of moving a unit of goods per unit of distance; therefore, accurate calculation of the distance between departments is an issue of paramount importance. In the literature, the distance between the departments is measured in three ways: Euclidean distance,... 

The behavior of soil-structure interface plays an important role in the static and dynamic analysis of soil-structure systems. Development of new materials such as polymer concrete requires an understanding of the behavior and their interaction with other materials. In this investigation, the interface behavior between polymer concrete and ordinary concrete with sand was studied using interface direct shear tests. In order to find optimum content of epoxy resin for polymer concrete, a series of tensile and compressive tests were conducted. To study the mechanical properties of concretes-sand interfaces behavior two series of interface direct shear tests were conducted at three different... 

The understanding of the mechanical behavior of engineering materials and their interfaces plays an important role in the prediction, analysis, and desing of engineering systems. Considering the important role of understanding and describing the behavior of materials and systems, this thesis is devided into three sections: 1) Modeling the behavior of polymer concrete under uniaxial compression, 2) Modeling the behavior of various light- and normal- weight concretes under uniaxial and triaxial compression, and 3) Modeling the behaivor of interfaces between polymer concrete and normal concrete with sand. In this context, various constitutive models were investigated and compared together,... 

In order to enhance the behavior of structures during an earthquake, various system have been proposed and used in recent years. The main purpose of these systems is to provide enough deuctility to dissipate the input energy of the earthquake. Buckling restrained braces are used extensively in seismic-restraint structures due to their sutiable cyclic behavior. They consist of a core energy dissipation and external restraining component. The purpose of this study is to improve the behavior of BRBs using FRP strips as a restraining component. In this study ABAQUS is used to model analyze the structure. Concrete Damage Plasticity (CPD) is used to model concrete, Hashin model used for FRP strips... 

Understanding and defining mechanical behavior of engineering materials play an important role in the prediction of material response as well as analysis and design of engineering structures. In this investigation, polymer concrete (PC) with three different epoxy resin contents, ordinary cement concrete (OCC), lightweight concrete (LWC) and lime-mortar soil (LMS) have been studied under uniaxial and triaxial compression tests to determine their mechanical behavior by measuring axial stress-strain and volumetric strain versus axial strain curves. According to the results, PC showed higher strength, ductility and energy absorption than that of OCC and LWC. Nowadays, waste tire rubber is used... 

This study has investigated the effects of different environmental conditions on the bond at the interface between two fiber reinforced polymer (FRP) layers. A total of 945 single lap splice coupons with three bond length were made using wet lay-up technic. There were used three unidirectional fabrics and one type of epoxy resin. A Uniaxial tensile test was performed on samples after 2, 4, 12, 20, 28, 36 and 48 weeks of exposure. Also series of test were conducted in order to determine the minimum lap splice length of single splice FRP samples. The experimental results indicated reduction of bond strength in glass specimens that was 17 % after 48 weeks of exposure while for same amount of... 

Ground granulated blast furnace slag (GGBFS) based alkali-activated concrete (GAAC) is one of the eco-friendly alternatives of traditional concrete, which uses industrial byproducts instead of ordinary Portland cement (OPC). Besides environmental benefits, substituting OPC concrete with GAAC has some economic advantages, while it successfully meets the concrete structural requirements in both mechanical and durability characteristics. Despite this fact, employing GAAC in the construction industry has been limited due to a lack of standard mix design code.This study aims to develop an accurate prediction model for the compressive strength of GAAC by employing the most appropriate machine... 

In recent decades, particle composite materials have a wide range of applications in engineering. Particle composites are a group of heterogeneous materials with different length scales and are characterized by particles that are randomly distributed in a matrix phase. Geopolymer concrete is a special type of concrete that its binder is made by reacting alumina and silicate carriers with an activating agent and in recent years with the expansion of its use has reduced the amount of cement consumption. In addition to the many advantages of geopolymer concrete, it has disadvantages in terms of setting time. That is why the use of cement has been proposed as a solution to the problem. This... 

Alkali-activated fly ash-slag (AAFS) is a new type of sustainable construction material widely studied in recent years for its desirable mechanical properties and low environmental impacts. In this study, the effects of the slag incorporation from 10 to 30% of fly ash are investigated on the strength, pore structure, and transport properties of the AAFS with various levels of fly ash replacements with slag. The unconfined compression and ultrasonic pulse velocity tests were performed to evaluate the mechanical properties of the AAFS concrete. Microstructural and mineralogical changes were studied by porosity, N2-adsorption/desorption, and SEM/EDX tests. Additionally, transport properties... 

Nowadays, construction with earthen materials has become more widespread due to their advantages: low construction cost, low embodied energy, application of green materials, and recyclability. Rammed earth (RE) as a sustainable construction has been used worldwide for decades. They are built in many countries such as Australia, China, India, and many parts of Africa and Europe. The rammed earth materials are cheap, accessible, and green and provide good thermal buffering. Stabilizers such as cement and lime with high embodied energy are frequently used in rammed earth construction to enhance materials' mechanical properties and durability. Stabilizers in RE materials could affect the energy... 

The behavior of construction materials at high temperatures has been an important aspect of researches in recent years. The first part of the current research aims to non-destructively monitor the formation and growth of damage at geopolymer concrete (GPC) after being exposed to high temperatures using linear and nonlinear ultrasonic techniques. Ultrasonic waveform and pulse velocity (UPV) tests were conducted on the specimens before and after exposure to the temperatures. Nonlinear wave signals were processed in phase-space domain for qualitative health monitoring of GPC. Furthermore, feature extraction was applied to phase-plane attractors using fractal dimension for quantitative... 

Selecting a suitable material is crucial for repairing the old concrete structures and joining precast panels of bridges, especially the bond strength between the substrate concrete and the overlay material. In this regard, this research focused on high-performance alkali-activated slag concrete (HPASC) as a new concrete used as an overlay on ordinary Portland cement concrete (OPCC) as a block of old concrete. Approximately four hundred bi-surface shear (BSS) tests were performed to evaluate the interface properties of OPCC and HPASC. HPASC specimens were designed with different NaOH molarity, silica fume (SF) content, steel fiber content, age of repair material, and proportion of grooved... 

In this thesis, supervised and unsupervised deep learning-based frameworks were proposed for distributed damage detection and quantification in concrete using sinusoidal ultrasonic response signals. Before the main study on ultrasonic-based concrete damage assessment, a preliminary study was performed on deep learning-based concrete compressive strength prediction. In this study, convolutional neural networks were utilized to predict the compressive strength of concrete through its mix proportions. The Genetic algorithm was employed to find the optimum number of filters in each convolutional layer of the convolutional neural networks. The proposed framework demonstrated high accuracy in... 

This study aims to evaluate the seismic behavior of geotextile-reinforced soil retaining walls by using incremental dynamic analysis and endurance time analysis methods. Five different wall models with variables of length and the modulus of elasticity of reinforcements have been constructed in the ABAQUS finite element software. In this study, the soil behavior and the interaction between the soil and reinforcement are modeled using a fully plastic linear elastic behavior model based on the Mohr-Coulomb yield criterion. Despite reinforced retaining walls' numerous benefits and extensive use, there is an obvious need for more precise design and a better knowledge of these structures' static...