The deep space network

Network engineering, hardware and software development, and tracking station operations for support of deep space unmanned flight projects are summarized

In-plane shear behaviour of composite walling with profiled steel sheeting

This thesis introduces a novel form of double skin composite walling with profiled steel sheeting and an infill of concrete. This is a logical extension of research on composite slabs with profiled steel sheeting currently known as popular "Fastrack" construction. The composite walling is thought to be specially applicable as shear or core walls in steel frame buildings. The profiled steel sheeting will act as a temporary shear bracing to stabilise the frame against wind and destablising forces during construction and also act as a form work for infill of concrete. In the service stage, they will act as a reinforcement to carry axial, lateral and in-plane forces. This thesis investigates the behaviour of composite walls under in-plane shear so that they can be used as shear elements in buildings. The investigation includes analytical, numerical and small scale model tests. Design recommendations for the composite walls are the final aim of the research. The investigation is based on the concept that the in-plane shear strength and stiffness of the composite wall will be derived from the individual sheeting, concrete core and from the interaction between the two. Based on above, individual behaviour of the sheeting and concrete core was studied before considering the composite wall as a whole. A shear rig has been designed and fabricated to carry out the model tests of approximately 1/6 th scale using very thin sheeting (profiled in house) and microconcrete. Analytical equations for the shear strength and stiffness of the sheeting, profiled concrete and composite wall are derived. These equations are validated by model tests and finite element analysis. Finite element analysis included modelling of composite walling with full composite action and some parametric studies using interface elements. The stiffness of the composite wall is found to be greater than the individual summation of stiffness of the sheeting and concrete core. The profiled steel sheeting will provide sufficient shear bracing to the frame during construction. The composite wall is capable of taking high in-plane shear loads which is greater than the summation of individual capacity of the sheeting and concrete and confirms its potential to be used as shear elements in buildings. Simple equations for the calculation of shear strength and stiffness of the composite wall are derived which can safely be used for design purposes. Further research directions are also outlined.This thesis introduces a novel form of double skin composite walling with profiled steel sheeting and an infill of concrete. This is a logical extension of research on composite slabs with profiled steel sheeting currently known as popular "Fastrack" construction. The composite walling is thought to be specially applicable as shear or core walls in steel frame buildings. The profiled steel sheeting will act as a temporary shear bracing to stabilise the frame against wind and destablising forces during construction and also act as a form work for infill of concrete. In the service stage, they will act as a reinforcement to carry axial, lateral and in-plane forces. This thesis investigates the behaviour of composite walls under in-plane shear so that they can be used as shear elements in buildings. The investigation includes analytical, numerical and small scale model tests. Design recommendations for the composite walls are the final aim of the research. The investigation is based on the concept that the in-plane shear strength and stiffness of the composite wall will be derived from the individual sheeting, concrete core and from the interaction between the two. Based on above, individual behaviour of the sheeting and concrete core was studied before considering the composite wall as a whole. A shear rig has been designed and fabricated to carry out the model tests of approximately 1/6 th scale using very thin sheeting (profiled in house) and microconcrete. Analytical equations for the shear strength and stiffness of the sheeting, profiled concrete and composite wall are derived. These equations are validated by model tests and finite element analysis. Finite element analysis included modelling of composite walling with full composite action and some parametric studies using interface elements. The stiffness of the composite wall is found to be greater than the individual summation of stiffness of the sheeting and concrete core. The profiled steel sheeting will provide sufficient shear bracing to the frame during construction. The composite wall is capable of taking high in-plane shear loads which is greater than the summation of individual capacity of the sheeting and concrete and confirms its potential to be used as shear elements in buildings. Simple equations for the calculation of shear strength and stiffness of the composite wall are derived which can safely be used for design purposes. Further research directions are also outlined

STEEL BEAMS STRENGTHENED WITH ULTRA HIGH MODULUS CFRP LAMINATES

Advanced composites have become one of the most popular methods of repairing and/or strengthening civil infrastructure in the past couple of decades. While the use of Fiber Reinforced Polymer laminates and sheets for the repair and strengthening of reinforced concrete structures is well established, research on the application of FRP composites to steel structures has been limited. The use of FRP material for the repair and rehabilitation of steel members has numerous benefits over the traditional methods of bolting or welding of steel plates. Carbon FRPs (CFRPs) have been preferred over other FRP material for strengthening of steel structures since CFRPs tend to posses higher stiffness. The emergence of high modulus CFRP plates, with an elastic modulus higher than that of steel, enables researchers to achieve substantial load transfer in steel beams before the steel yields. This research investigates both analytically and experimentally, the bond characteristics between ultra high modulus CFRP strengthened steel members and the flexural behavior of these members. A series of double strap joint tests with two different CFRP strip widths are carried out to evaluate the development length of the bond. Both ultra high modulus and normal modulus CFRP laminates are used to compare strengthened member performance. Steel plates reinforced with CFRP laminates on both sides are loaded in tension to evaluate the load transfer characteristics. Debonding under flexural loads is also studied for ultra high modulus CFRP strengthened steel girders. Flexural tests are carried out under 4-point bending on several small scale wide flange beams. This study also introduces the novel ultra high modulus CFRP plate strip panels for strengthening of steel bridge girders. The first field application of ultra high modulus CFRP laminates in strengthening steel bridge girders in the United States is also carried out as part of the research. Full scale load tests carried out before and after the strengthening are utilized to measure the degree of strengthening achieved and checked against the expected results. A finite element model is developed and calibrated using data obtained from the field testing of the bridge. The model is then used to evaluate the behavior of the bridge under different conditions before and after the strengthening process

Journal of Telecommunications and Information Technology, 2004, nr 4

kwartalni

Shear connection of a prefabricated lightweight steel-concrete composite flooring system

This research PhD thesis investigates the shear connection behaviours and failure modes of two new connection systems used in a newly proposed fully prefabricated lightweight ultra shallow flooring system. The shear connection systems are different to anything presented up to date in the literature and they serve the purpose of the novel prefabricated slab. Experimental, computational and analytical studies were carried out with the aim of improving and optimising the design details, as well as advancing the method of shear connection systems in the prefabricated ultra shallow slabs. A comprehensive Life Cycle Assessment (LCA) was initially performed, followed by an extensive literature review in order to understand the characteristics of shallow and lightweight steel-concrete composite flooring systems. The LCA study resulted in selecting the materials of the prefabricated ultra shallow flooring system (lightweight concrete and steel), before designing the flooring system. Moreover, analytical LCA and LCC studies were also carried out to examine the ecological impact of the new flooring systems, which were then compared with existing prefabricated shallow flooring systems, such as the hollow core precast slab and Cofradal slab. The prefabricated ultra shallow flooring system proposed in this research was developed by this PhD research programme. It is made of a T-ribbed lightweight concrete floor and C-channel steel edge beams, connected with the use of web-welded shear studs (herein called WWSS), and in some cases, horizontally lying dowels too. Their unique configuration minimises its structural depth and results in ultra-shallow floors (structural depths). Thus, two types of shear connection systems were studied: (a) web-welded shear studs only (WWSS), and (b) web-welded shear studs with dowels (WWSS with dowels). In total, eight (8) full scale push-out tests were conducted in the Heavy Structures Laboratory at the University of Leeds, to examine the load-slip behaviour and longitudinal shear resistance of the two shear connection systems under direct shear force. The failure mechanisms of the two forms of shear connection systems were extensively studied, which led to the development of a design method for calculating the shear capacity. Finite Element Analyses (FEA) of the shear connection systems were then performed, supported by eighty four (84) parametric models to further verify the design method that was previously established. Finally, an accurate and reliable moment resistance design method of the prefabricated ultra shallow flooring system was proposed as a practical outcome of this PhD thesis in accordance with the Eurocode 4 and BS5950 standards

Stress-Crack Separation Relationship for Macrosynthetic, Steel and Hybrid Fiber Reinforced Concrete

An experimental evaluation of the crack propaga tion and post-cracking response of macro fiber reinforced concrete in flexure is c onducted. Two types of structur al fibers, hooked end steel fibers and continuousl y embossed macro-synthetic fibers are used in this study. A fiber blend of the two fibers is evaluated for spec ific improvements in the post peak residual load carrying response. At 0.5% volume fraction, both steel and macrosynthetic fiber reinforced concrete exhibits load recovery at large crack opening. The blend of 0.2% macrosynthetic fibers and 0.3% steel fibers shows a significa nt improvement in the immediate post peak load response with a significantly smaller load drop and a constant residual load carrying capacity equal to 80% of the peak load. An analytical formulation to predict fle xure load-displacement behaviour considering a multi-linear stress- crack separation (σ -w) relationship is developed. An inverse analysis is developed for obtaining the multi- linear σ -w relation, from the experimental response. The � -w curves of the steel and macrosynthetic fiber reinforced concrete exhibit a stress recovery after a significant drop with increa sing crack opening. Significant residual load carrying capacity is attained only at large crack separation. The fiber blend exhibits a constant residual stress with increasing crack sepa ration following an initial decrease. The constant residual stress is attained at a small crack separation

The Black Book of Quantum Chromodynamics

The LHC (Large Hadron Collider) will serve as the energy frontier for high-energy physics for the next 20 years. The highlight of the LHC running so far has been the discovery of the Higgs boson, but the LHC programme has also consisted of the measurement of a myriad of other Standard Model processes, as well as searches for Beyond-the-Standard-Model physics, and the discrimination between possible new physics signatures and their Standard Model backgrounds. Essentially all of the physics processes at the LHC depend on quantum chromodynamics, or QCD, in the production, or in the decay stages, or in both. This book has been written as an advanced primer for physics at the LHC, providing a pedagogical guide for the calculation of QCD and Standard Model predictions, using state-of-the-art theoretical frameworks. The predictions are compared to both the legacy data from the Tevatron, as well as the data obtained thus far from the LHC, with intuitive connections between data and theory supplied where possible. The book is written at a level suitable for advanced graduate students, and thus could be used in a graduate course, but is also intended for every physicist interested in physics at the LHC

The Black Book of Quantum Chromodynamics

The LHC (Large Hadron Collider) will serve as the energy frontier for high-energy physics for the next 20 years. The highlight of the LHC running so far has been the discovery of the Higgs boson, but the LHC programme has also consisted of the measurement of a myriad of other Standard Model processes, as well as searches for Beyond-the-Standard-Model physics, and the discrimination between possible new physics signatures and their Standard Model backgrounds. Essentially all of the physics processes at the LHC depend on quantum chromodynamics, or QCD, in the production, or in the decay stages, or in both. This book has been written as an advanced primer for physics at the LHC, providing a pedagogical guide for the calculation of QCD and Standard Model predictions, using state-of-the-art theoretical frameworks. The predictions are compared to both the legacy data from the Tevatron, as well as the data obtained thus far from the LHC, with intuitive connections between data and theory supplied where possible. The book is written at a level suitable for advanced graduate students, and thus could be used in a graduate course, but is also intended for every physicist interested in physics at the LHC