Sharif Digital Repository

In this research, we study the differences between the centralized and decentralized approaches in a two-stage serial supply chain including a manufacturer and a retailer under the lost sale policy. The centralized approach results in optimal solution of the system and the decentralized one is based on Stackelberg game in which the manufacturer is the leader. The retailer uses the continuous review (r, Q) policy and the demand arrives according to the stationary Poisson process. In order to obtain the solution for two approaches, a set of computational steps are developed. Furthermore, we provide a numerical example and the corresponding sensitivity analysis to compare the two approaches.... 

While there are many advantages associated with concrete, including high compressive strength, durability and so forth, on the contrary, it has several disadvantages which may make engineers somewhat reluctant to use it. These include low tensile strength, high brittleness, low resistance to impact, large dimensions of structural cross sections, etc. In recent years, there have been many attempts to surmount these disadvantages by various means such as adding pozzolans, using FRPs, fibres, etc. In this project, the effects of using a special type of high strength steel fibre is studied. In order to investigate the effect of this fibre on the compressive behavior of concrete, 30 cylindrical... 

Bridges are among the crucial elements of transportation networks and play an important role in facilitating emergency relief efforts following earthquakes. For this reasons, they should have an appropriate performance in earthquakes; Thus, presentation of true design of bridges was necessary. Elastic design of bridges due to the earthquake is uneconomic; hence, during an earthquake, the codes permitted to structures go to their inelastic behavior domain but inelastic analysis of structures are noncommercial and the capability of detail modeling of the inelastic behavior of the material is still impossible. Therefore, designers use response modification factor to consider the inelastic... 

Numerous research is available in the literature regarding shear walls. These have considered parameters like wall cross-section, Reinforcement configuration, boundary elements, etc. In addition, seismic and wind loading behavior has been discussed. Currently, the software ETABS is used extensively in automatic design of shear walls, The programs design bases are investigated in this thesis in ragards to flexural, shear and boundary elements of shear walls under seismic loading. The attachment of wall elements to frame (column) elements is of particular interest in this study  

The application of composite systems has rapidly advanced in bridge and building construction. Shear connectors are the most basic parts of the composite systems.The connectors transfer the shear forces between the slab and the beam. They also prevent separation of the slab from the beam.
Therefore researchers have done widespread studies on the behavior of shear connectors and their load carrying capacity. Steel angles are one of the shear connectors that can be used incompositesystems. Only limited number ofstudies has investigated thebehavior of thistype of connector.
The purpose of this thesis is to investigate the behavior of angle shear connectors embedded in solid concrete... 

Lateral forces on structures are transferred to braces as tensile and compressive loads. These loads enter the beams and columns through the gusset plates. The gusset connections to the beams and columns must be such that they be able to pass the loads through themselves. So far, five analytical models have been proposed for this connection and only one of them is recommended by AISC. These models estimate the existing forces and moments on the connection. The analytical models are: model 1 (KISS), model 2 (2A-AISC), model 3 (Thornton), model 4 (Ricker) and model 5 (Richard). Among these models, only model 3 is recommended by AISC because the others are more conservative. It should be noted... 

Cable-stayed bridges are the most economical solution for spans ranging from about 200 to 1000 meters. They have become more popular in recent decades due to their efficiency and appearance. The need to understand their seismic beahvior is apparent and any improvement can be useful. The main purpose of this study is to determine the effect of using three lateral cable arrangement groups namely, cross system, pulley system and spatial lateral cable system with two transversally inclined cable planes on seismic performance of cable-stayed bridges. In this research, the seismic consequences of these arrangements with interactions of key parameters like, the main span length and deck to pylon... 

The shear lag phenomenon is one of the effective factors in determining the tensile capacity of tension members. In this phenomenon, there are various factors including the size and type of the cross-section, the type of connection, the length of connection, thickness of gusset plate, etc. are effective. The previous studies which are the basis of the specification equations, have been conducted on the cross-sections with bolted and riveted connections, while no study has been conducted to determine the effects of some of these factors yet. Using numerical methods, the present study investigates and compares each of the effective parameters on shear lag phenomenon on the single and double... 

The steel-concrete composite beams are increasingly used in bridge and building construction in recent years. A shear connection between the steel and concrete should be provided to effectively transfer the shear force and to make the two materials act as a single unit. The mechanical shear connectors provide this means. They are the essential component of any composite beam system. Many studies have been performed on shear connectors and many different steel shapes have been suggested for connectors. The steel studs and channels are the most popular code accepted connectors. However, economic considerations continue to motivate the development of new products.
Present knowledge of the... 

According to recent researches, angle-shape shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. This study investigates the effect of tilted angle on capacity and behavior of angle-shape shear connectors. In this study, we consider two different tilted angles. Push-out tests consisting of eight specimens made of reinforced concrete and different angle-shapes were conducted. Specimens have tilted anglesof 112.5 and 135 degrees between the angle leg and steel beam. Two different failure modes were observed consisting of concrete crushing-splitting and angle fracture. In addition, a nonlinear finite element model of these push-out... 

In this thesis the shear strength of pipe shear connector is investigated experimentally and numerically. The numerical analysis uses a nonlinear finite element model of the push-out specimen. The specimens consist of the pipe shear connector, steel beam, concrete slab and embedded steel rebar for concrete confinement. Eight push-out specimens are constructed with different pipe sizes and concrete strength. The results are used in a finite element parametric study to evaluate the strength of such connectors for all practical ranges of pipe size and concrete strength. It is shown that pipe connectors are more effective in transferring shear forces than angle and channel and stud connectors....