Coupled Instabilities in Metal Structures: Theoretical and Design Aspects

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The aim of the book is to fill up the gaps between theoretical, numerical, and practical design approaches in the field of coupled instabilities of metal structures. The book is organized in a way leading progressively from the mathematical basic theories to the design aspects through numerical and semi-empirical approaches of the interactive buckling of metal structures. Optimum design account taken of coupled instabilities and code aspects are also briefly covered.

Convert currency. Add to Basket. Book Description Springer, Condition: New. More information about this seller Contact this seller. Book Description Springer Vienna , Berlin, Seller Inventory Book Description Springer Vienna Mai , Condition: Neu. Neuware - The aim of the book is to fill up the gaps between theoretical, numerical, and practical design approaches in the field of coupled instabilities of metal structures. Language: English. Brand new Book.

Seller Inventory AAV Model-based systems engineering predicts potentially problematic interactions, while computational analysis and optimization allows designers to explore more options early in the process. Increasing automation in engineering and manufacturing allows faster and cheaper development. Technology advances from materials to manufacturing enable more complex design variations like multifunction parts.

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Once impossible to design or construct, these can now be 3D printed , but they have yet to prove their utility in applications like the Northrop Grumman B or the re-engined Aneo and MAX. Airbus and Boeing also recognize the economic limits, that the next airliner generation cannot cost more than the previous ones did. An increase in the number of aircraft also means greater carbon emissions.

Environmental scientists have voiced concern over the main kinds of pollution associated with aircraft, mainly noise and emissions. Aircraft engines have been historically notorious for creating noise pollution and the expansion of airways over already congested and polluted cities have drawn heavy criticism, making it necessary to have environmental policies for aircraft noise. Environmental limitations also affect airfield compatibility.

Airports around the world have been built to suit the topography of the particular region. Space limitations, pavement design, runway end safety areas and the unique location of airport are some of the airport factors that influence aircraft design. However changes in aircraft design also influence airfield design as well, for instance, the recent introduction of new large aircraft NLAs such as the superjumbo Airbus A , have led to airports worldwide redesigning their facilities to accommodate its large size and service requirements. The high speeds, fuel tanks, atmospheric conditions at cruise altitudes, natural hazards thunderstorms, hail and bird strikes and human error are some of the many hazards that pose a threat to air travel.

Airworthiness is the standard by which aircraft are determined fit to fly.

Difference between Analysis and Design of Structures

The International Civil Aviation Organization sets international standards and recommended practices for national authorities to base their regulations on [21] [22] The national regulatory authorities set standards for airworthiness, issue certificates to manufacturers and operators and the standards of personnel training. The aircraft manufacturer makes sure that the aircraft meets existing design standards, defines the operating limitations and maintenance schedules and provides support and maintenance throughout the operational life of the aircraft.

Coupled Instabilities In Metal Structures: Cims'96

The aviation operators include the passenger and cargo airliners , air forces and owners of private aircraft. They agree to comply with the regulations set by the regulatory bodies, understand the limitations of the aircraft as specified by the manufacturer, report defects and assist the manufacturers in keeping up the airworthiness standards. Most of the design criticisms these days are built on crashworthiness. Even with the greatest attention to airworthiness, accidents still occur.

Crashworthiness is the qualitative evaluation of how aircraft survive an accident. The main objective is to protect the passengers or valuable cargo from the damage caused by an accident. In the case of airliners the stressed skin of the pressurized fuselage provides this feature, but in the event of a nose or tail impact, large bending moments build all the way through the fuselage, causing fractures in the shell, causing the fuselage to break up into smaller sections.

Aircraft are sometimes designed with emergency water landing in mind, for instance the Airbus A has a 'ditching' switch that closes valves and openings beneath the aircraft slowing the ingress of water. Aircraft designers normally rough-out the initial design with consideration of all the constraints on their design. Historically design teams used to be small, usually headed by a Chief Designer who knows all the design requirements and objectives and coordinated the team accordingly.

As time progressed, the complexity of military and airline aircraft also grew. Modern military and airline design projects are of such a large scale that every design aspect is tackled by different teams and then brought together. In general aviation a large number of light aircraft are designed and built by amateur hobbyists and enthusiasts.

In the early years of aircraft design, designers generally used analytical theory to do the various engineering calculations that go into the design process along with a lot of experimentation. These calculations were labour-intensive and time-consuming. In the s, several engineers started looking for ways to automate and simplify the calculation process and many relations and semi-empirical formulas were developed.

Even after simplification, the calculations continued to be extensive. With the invention of the computer, engineers realized that a majority of the calculations could be automated, but the lack of design visualization and the huge amount of experimentation involved kept the field of aircraft design stagnant. With the rise of programming languages, engineers could now write programs that were tailored to design an aircraft. Originally this was done with mainframe computers and used low-level programming languages that required the user to be fluent in the language and know the architecture of the computer.

With the introduction of personal computers, design programs began employing a more user-friendly approach. All aircraft designs involve compromises of these factors to achieve the design mission. The wing of a fixed-wing aircraft provides the lift necessary for flight. Wing geometry affects every aspect of an aircraft's flight.

The wing area will usually be dictated by the desired stalling speed but the overall shape of the planform and other detail aspects may be influenced by wing layout factors. The wing design depends on many parameters such as selection of aspect ratio , taper ratio, sweepback angle, thickness ratio, section profile, washout and dihedral. Ribs can be made of wood, metal, plastic or even composites. The wing must be designed and tested to ensure it can withstand the maximum loads imposed by maneuvering, and by atmospheric gusts.

The fuselage is the part of the aircraft that contains the cockpit, passenger cabin or cargo hold. Aircraft propulsion may be achieved by specially designed aircraft engines, adapted auto, motorcycle or snowmobile engines, electric engines or even human muscle power. The main parameters of engine design are: [ citation needed ]. The thrust provided by the engine must balance the drag at cruise speed and be greater than the drag to allow acceleration. The engine requirement varies with the type of aircraft. For instance, commercial airliners spend more time in cruise speed and need more engine efficiency.

High-performance fighter jets need very high acceleration and therefore have very high thrust requirements. The weight of the aircraft is the common factor that links all aspects of aircraft design such as aerodynamics, structure, and propulsion, all together. An aircraft's weight is derived from various factors such as empty weight, payload, useful load, etc. The various weights are used to then calculate the center of mass of the entire aircraft. The aircraft structure focuses not only on strength, stiffness, durability fatigue , fracture toughness, stability, but also on fail-safety, corrosion resistance, maintainability and ease of manufacturing.

Generally, elastic analysis is used. Plastic analysis and elastic-plastic analysis is generally only used for the design of portal frames. Although manual methods of analysis may be used, most designers find it convenient to use readily available software. Modelling members. Most software contains libraries of all the standard steel sections , with the associated member properties used in the analysis. Non-standard members may be modelled with equivalent section properties. Tapered or haunched members may be modelled with a number of short elements, each with different section properties.

Curved members may be modelled with a series of straight members. Modelling Joints. Common UK practice is to assume joints are either nominally pinned and modelled as perfectly pinned or nominally rigid and modelled as perfectly rigid. It is then important to ensure that the physical details correspond to the design assumptions. All frames experience second-order effects , typically because under lateral loads or simply due to frame imperfections , the vertical loads are no longer concentric with the bases.

The effect of this displacement is not accounted for in a first-order analysis. Some frames are sufficiently stiff such that second-order effects are small enough to be ignored. When second-order effects must be accounted for, this can be achieved by using second-order analysis, or by a simple amplifier of the lateral loads.

Design -

All frames must be assessed for sensitivity to second-order effects , and these effects allowed for if necessary. Main articles: Design codes and standards. The over-arching requirement for design in the UK is to satisfy the Building Regulations. Practically, design of steel structures will generally be in accordance with BS [4] or the Eurocodes. Building Regulations require that a safe structure be constructed. Although a series of design Standards are cited in the Regulations, there is no absolute requirement that the listed Standards are used for design.

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Although BS [4] was withdrawn in March , it is likely to be used for steel building design for a number of years. The advantages of design to BS include:. The Eurocodes are a set of unified structural design standards for use across Europe, developed by CEN European Committee for Standardisation , to cover the design of all types of structures in steel, concrete, timber, masonry and aluminium.

In addition to the Eurocodes and the National Annex, non-contradictory complementary information NCCI is provided, to provide further guidance on the application of the Eurocodes.

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The National Annex NA is an essential document when using any Eurocode Part; the relevant NA covers the country where the construction will take place. Where the opportunity is given in the text of the Eurocode, the National Annex will:. The National Annex may give references to publications and other guidance containing non contradictory complementary information NCCI that will assist the designer when designing a structure to the Eurocodes.

The Eurocodes omit some design guidance where it is considered to be readily available in text books or other established sources. These NCCI documents are informative, without the status of a Standard, but are generally helpful reference documents for designers. It also describes the basis for structural design and verification.

The commonly used Parts include:. Additional rules are provided in separate Parts for other structures, e. A comprehensive range of design guidance is available for use in the UK, all incorporating the influence of the UK National Annexes. BS EN [12] covers the design of composite structures and elements. Main articles: Braced frames , Continuous frames , Composite construction , Floor systems , Steel construction products , Long-span beams.

Building frames may be broadly classified by their stability system, as braced or continuous frames. A portal frame is a particular type of a continuous frame. For multi-storey frames , a braced frame is likely to be most economical, because the fabrication effort for the joints in braced frames is generally much less than for joints in continuous frames.

Continuous frames must be used when bracing cannot be provided within the structure. Within both types of frame, a wide range of floor systems is available. Several floor systems utilise the benefits of composite construction , which will be the de facto solution for many structures. The floor systems in common use are briefly described in the following sections. Composite construction is the dominant form of construction for the multi-storey building sector. Its success is due to the strength and stiffness that can be achieved, with minimum use of materials, utilising the compressive strength of concrete and the tensile strength of steel.

Composite floors offer significant advantages related to speed of construction and reduced overall construction depth. Composite floor slabs generally use either relatively shallow profiled steel decking , typically spanning up to 3. Composite floor slabs may also be constructed using pre-cast planks as the permanent formwork. Floor slabs may be formed from pre-cast planks, but still allow the supporting beam to be designed as a composite member.

Composite beams involve the transfer of force between the steel section and the concrete which it supports, preventing slip and thus ensuring the two elements perform as a composite whole. For beams located wholly under the slab known as "downstand" beams the transfer of force is commonly achieved using headed shear studs, which are attached to the upper flange of the steel beam.

Studs are usually welded on site, through the decking, to the unpainted top flange of the beam. Alternatively, smaller shear connectors may be shot-fired to the steel beam. In some forms of construction, the shear bond between the steel member and the encasing concrete is sufficient to provide composite action without additional shear connectors.

Precast concrete units may be used in conjunction with steel beams. The units may be solid or hollow-core, and with tapered or bluff ends. They are normally prestressed.

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  6. The steel beams and precast units may be designed as a composite member, provided specific detailing rules are satisfied to ensure the necessary composite behaviour. Integrated or 'shallow' floors offer a range of benefits, including a reduced construction depth compared to an orthodox "downstand" solution and, in some solutions, a virtually flat soffit, allowing easy location of services. A number of integrated floor solutions are available, including a range of rolled and fabricated options providing shallow depth members with wide bottom flanges, so that precast planks or steel decking can be placed on the bottom flange.

    Long spans result in flexible, column-free internal spaces, reduced substructure costs, and reduced erection times. This broad range of benefits means that they are commonly used in a wide range of building types. For some types of beam this codified guidance is complemented by specific design guidance, such as that on the design of beams with large web openings , or manufacturers' software.

    A truss is essentially a triangulated system of straight interconnected structural elements. The most common use of trusses is in buildings, where support to roofs, the floors and internal loading such as services and suspended ceilings, is readily provided. Trusses are commonly used in a range of buildings including airport terminals, aircraft hangers, sports stadia roofs, auditoriums and other leisure buildings. Trusses are also used to provide large column-free spaces in commercial buildings. The main reasons for using trusses are:. Trusses may be exposed within the structure and be fabricated from hollow sections for aesthetic appeal.

    Large loads may require the use of open sections UKC, typically or sections built up from plate.