Sharif Digital Repository

One of the most significant factors for the on-time and successful implementation of construction projects is contract management. Proper management of construction contracts and assessment of potential risks in the bidding process and before its signing have a significant impact on preventing or reducing the occurrence of claims and disputes between the contract parties at various stages of the project. In this research, using the latest deep learning (DL) and natural language processing (NLP) state-of-the-art methods, and various deep neural networks (DNN) architectures a model has been developed for extracting Persian contract risk-prone clauses. In addition, this study provides a... 

Due to major problems induced by delamination in laminated composites, functionally-graded materials (FGM) have been put to growing use in recent years. In the present research, dynamic stability of FGM cylindrical shells under axial follower loads is addressed. Loading was considered in three forms: concentrated (Beck’s problem), uniformly-distributed (Leipholz’s problem), and linearly-distributed (Hauger’s problem). In order to derive the governing equations, Love’s hypotheses and First-order Shear Theory (FST) were used. To solve the equations, polynomial mode shapes were used to approximate the displacements, and the extended Galerkin method was applied. The problem was solved for mild... 

The use of steel as one of the most widely used materials in the construction of structures is accompanied by problems and among them the problem of establishing stability in structure is important. To provide stability in the structure as a whole and for each of its elements, the new edition of the American Specification for Structural Steel Buildings, has introduced three general methods based on the elastic analysis. It includes, direct analysis method, effective length method and first-order analysis method. Each method has advantages and disadvantages. The present study is divided into two parts. The first part gives an overview of the behavior of structures and methods of determining... 

High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use... 

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related... 

today's financial markets such as stock market are more attractive and important position and wealth are considered income and therefore attracts many people have. But the other hand, activity in these markets requires a high risk of admission. The point that is important is that the risk of investing in these markets can be predicted to some extent with the trend of stocks and securities can be controlled. Time series trend of stock prices and non-static characters is excited. But analysis of such behavior is impossible, i.e., reliance on sophisticated tools and of course accept the possibility of an error can be predicted price to pay. Synthetic models of artificial intelligence today, due... 

In this work a model of anisotropic plastic-damage , using thermodynamic framework is going to be proposed. This model was applied in simulating metals behavior. Using this model, besides plastic behavior will help us observe the impact of growth and coalescence of microdefects of material. Generally anisotropic damage application can demonstrate a more realistic behavior in material modeling. To get consistency equation and microdefects growth condition, irreversible thermodynamic will be used. Firstly, the plastic relationships have been written in undamaged configuration; then, using relationships between damaged and undamaged configuration, plastic equations are generalized to damage... 

In concrete which is a quasi-brittle material failure initially occurs between aggregate and mortars. Fibers of all orientations, randomly embedded in FRC, serve to restrict and delay the coalescence of micro-cracks, micro-voids and micro-slips into wide continuous cracks. While the fibers increase the uniaxial tensile and compressive strength only moderately, they are very effective for enhancing the ductility and energy absorption capability. This elevates structure resistance to impact, ground-shock and blast. One of the most successful efforts toward reaching a macroscopic model which can take micromechanical properties into account is the Microplane model. In this microscopic... 

Northridge earthquake in 1994 which damaged over 200 connections in moment resisting frames showed improper performance of regular connections. After this earthquake, diverse investigations have been started to clarify reasons of these failures and surveying new methods for their rehabilitation. Behavior of beam to column connections can be improved by shifting the location of inelasticity away from column’s face. Such connections can be achieved by reducing flange area of beams at a specific distance from column’s face, and they have been approved by various design codes. Another kind of these connections can be achieved by perforating beam’s web. Research on latter case shows that, if... 

The structural behavior of deep beams is different with usual beams as a result of the low span-to-height ratio. Shear failure load is less for deep beams. Implementation of externally bonded reinforcement such as fiber reinforced polymers (FRP) is a unique method for shear strengthening of deep beams. In this study, the effects of FRP layers on the web of the reinforced concrete deep beam have been investigated by a nonlinear finite element program. Five beams four of which were strengthened with FRP laminates were numerically modeled and the results were compared with experimental results. The effect of some governing parameters such as compressive strength of concrete, orientation of... 

Concrete as a heterogeneous, quasibrittle and practical material has always been a challenging material for modeling. Although numerous models have been proposed since now, many of them have some deficits. Microplane is a multiscale model which introduces some micro-planes as interaction planes between concete and aggregates. To generate concrete behavior, stress-strain relations are established on these micro-planes. In the present study, two prominent microplane models, M2 and M4, has been used in 2D and 3D Finite element framework. M2 model has been applied and developed to produce FRC behavior for uniaxial tension and compression under static and cyclic loading. To better optimize M2... 

Heavy damage developed from near field earthquake in resent years cause serious attention to this problem. Investigation shows that these records include large energy pulse, unlike far field earthquake. Overall effect of near field earthquakes ignored in the most building codes. The purpose of this investigation to find effect of near field earthquake on reinforced concrete moment frames. To achieve this goal Erduran damage index is efficient way to calculate damage. Two 4th and 8th story reinforcement concrete moment frame buildinges with moderate and high ductility designed by strength criterion. Seven pairs of near field earthquakes and seven pairs of far field earthquakes scaled and use... 

Reinforced concrete slabs carry both vertical gravity loads and in plane forces due to seismic loads. In this study interaction of bending and in plane forces will be considered. Lee et al. in 2007 studied the floor diaphragm behavior. They considered combination of both in plane and out of plane loadings. In the most previous studies, the diaphragm behavior of a floor slab was represented by its behavior under in-plane forces only. With this assumption, analysis of the floor diaphragm was simplified to the two dimensional plane stress problem. For low-rise buildings, the lateral stiffness of the structure is usually higher than high-rise buildings.Tena et al. in 2014 assessed ment the... 

A brief overview of the proposed research, its aims, engineering relevance and applications; as well as expected achievements compared to the present state of the art:The plastic hinge length and ultimate drift calculations of frames are required in the performance based design of reinforce concrete structure. FRP-confinement increases the column’s shear resistance and ductility. FRP-confinement prevents concrete cover from spalling and increases the inelastic deformability of concrete in the potential plastic hinge region. GU et al. 2012 [24] studied the existing experimental results of confinement effects on the plastic hinge length. Mortezaei and Ronagh, 2012 [25], studied the plastic... 

High performance concrete has a compressive strength of more than one hundred and twenty MPa. The effect of steel fibers on the flexural fracture of this type of concrete has been studied, but the mechanical behavior of fracture of this material has not been fully studied yet. In this research, the effect of different percentages of propylene fibers on the mechanical properties of reinforced concrete will be investigated experimentaly. For this purpose, beam samples with dimensions of 40*10*10 cm, which had an initial notch with a depth of 3 cm in the lower middle of it, have been tested to investigate the effect of fiber percentage on how the crack propegate and the sample breaks. It is... 

The present study was conducted to provide an overview of engineers and employers to select the best exterior procedure of the facade by examining the influential factors and the advantages and disadvantages of each facade in terms of construction. Therefore, to select the most efficient type of facade for each project, the types of external facade procedures have been examined from different perspectives.In this study, to obtain the results of the questionnaires, a statistical population of 100 people consisting of engineers was used to collect information. These questionnaires are defined around the factors influencing the facade's choice (economic, human, sustainable, and technological... 

Although the moment frame can show deformable behavior against seismic loads, but its flexibility and low stiffness, especially in tall structures, cause the governance criterion to be designed. The use of eccentrically braced frames was able to solve the displacement problem to some extent, because it has the characteristics of both flexural frame systems and conccentric bracing. Different methods have been proposed to eliminate residual displacements in this type of system, one of which is the use of post tensioned cables. The aim of this study was to investigate the seismic behavior of a steel structure with a eccentrically braced frame system with post tension cable.The cables are anchor... 

This study presents a modified Microplane model in two-dimensional space which is capable of modeling anisotropic materials accurately. The main idea of Microplane model is to write constitutive equations in terms of vectors rather than tensors. Material constitutive laws are written for planes of every possible orientation to calculate the response of each plane to a given loading. Then the results of all the planes, called microplanes, are added up using Principle of Virtual Work (PVW) to form together the macroscopic response of the material. Microplane model with kinematic constraint is used in this study. Kinematic constraint states that microscopic (local) strain vector acting on each... 

Secure routing is a major key to service maintenance in wireless ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. Wormhole attack is one of the most severe active attacks to mobile ad hoc networks. Noting the resource limitations in such networks, nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a...