Academic literature on the topic 'Span structures'

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.<br>Includes bibliographical references (leaves 69-70).<br>In recent years, the application of cable structures in buildings has gained huge popularities. Although cable technology has been established since the 1950s, there is suddenly a surge in the number of its building application starting in the late 90s. This phenomenon is attributed to the recent advances in computational form finding, analysis and construction simulation, which make the design and construction of cable structures simpler and more economical. Although cable structures have been employed for different building applications, this thesis will concentrate only on the use of cable structures in wide span system. Five cable systems: simply suspended cables, pretensioned cable beams, pretensioned cable nets, tensioned straight cable nets and tensegric shells are studied for their mechanical properties and suitability for wide span uses. A case study is presented at the end of each system's description to illustrate its possible application. The paper will then conclude with a presentation of a general design methodology of a cable structure.<br>by Katherina Santoso.<br>M.Eng.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.<br>Includes bibliographical references (leaves 55-57).<br>Traditional approaches to structural design presuppose strength to be the dominant design requirement. But following new technologies and design methods, this assumption that strength requirements dominate is being challenged. In the design of horizontal structures, such as floor systems and pedestrian bridges, increasing lengths of column-free span and demands for material efficiency have led to an overall reduction in the structural properties of mass, stiffness and damping. These three properties traditionally controlled motion-related serviceability issues, but this is no longer the case. Engineers are increasingly reporting vibration problems in horizontal structures. Hence, the dominant design criterion has shifted from a basis of strength to one of motion. This thesis attempts to investigate the code requirements and state of the art analysis techniques involved in the vibration control of horizontal structures. Design techniques involving passive control, active control and some alternative control methods are discussed and evaluated, both qualitatively and quantitatively, through a series of example problems.<br>(cont.) Conventional engineering knowledge addresses vibration problems by increasing stiffness; however, this study indicates that these problems may be resolved much more efficiently by increasing damping, perhaps through the use of a tuned mass damper. Recommendations are made, suggesting that structural engineers should give serious consideration to the dominance of serviceability issues in design. As vibration problems continue to become more prevalent with ever-increasing span lengths, the time will come when non-traditional solutions, such as the use of tuned mass dampers to control vibrations, can no longer be ignored.<br>by Nicholas A. Shultz.<br>M.Eng.

One of the reasons for the low amount of timber in construction is a general lack of knowledge about timber engineering and how timber can be used to its full advantage. In this thesis the focus is 3D computer visualisation (3D VIZ) of non-residential long-span timber structures, used for storage, industry and sports where 3D VIZ is defined as a process where a 3D-model is enhanced with environmental information e.g. texture maps and realistic light effects. An area of interest is the possibilities to increase timber construction through communicating the aesthetical properties of an exposed timber structure through using 3D VIZ. The aim of this exploratory study is to develop a foundation for future theory building through analysing the construction process and its use of communication media with respect to communication theory and media richness. The study further proposes how the communication process of long-span timber structures can be enhanced by using 3D VIZ and identifies connections between the construction process, participants and project classification. In this thesis two major research strategies have been utilised, a case study and a survey. The first research strategy includes a cross-industry learning research setting, using two case studies, applied and analysed regarding industrial design and architecture. The case studies suggest that a practice of concurrent engineering (CE) in construction and frequent use of 3D-computer visualisation by integrated product teams (IPT) can help to enhance the aesthetical value of the final building. The case studies also confirm that 3D VIZ is useful as a communication tool in the construction industry and demonstrate that using 3D VIZ during the planning process affects the image of the final result created by those involved. The second research strategy includes an Internet-based survey where the usefulness of 3D VIZ during the construction process is evaluated. The results show that structural complexity, intended viewer and current building phase influence the benefit of 3D VIZ. A number of parameters needed to communicate the aesthetics of timber efficiently, i.e. textures, surface structures, true dimensions and realistic light effects, have been pointed out. The analysis regarding communication theory and media richness indicate that the need for rich media, 3D VIZ with high realism and high level of detail (LOD), is generally higher for external communication compared to internal communication between professionals. The need for rich media is also high in the beginning of every new phase, while the need will decrease in the end of the phase.<br>Godkänd; 2005; 20061221 (haneit)

One of the identified reasons for the low amount of timber construction in Sweden is a general lack of knowledge about timber engineering and how timber can be used to its full advantage. One way for increased timber construction is the development of a cost-efficient and easy to comprehend building system. Efficiency in construction has recently been under hot debate following the success of lean production in the manufacturing industry. Therefore, the attention of construction has been directed towards the manufacturing industry in an attempt to learn successful methods. Three main principles, modularity, lean construction, and buildability, emerge as potentially useful in order to streamline construction. The aim of this research project is to create a knowledge- based framework for long-span timber construction. This framework should be able to store knowledge and experience about timber construction as well as aid in the design and production of buildable timber structures. A buildable structure is here defined as a structure constructed in competition with all other materials and sub-system choices, i.e., by this definition a constructed structure is buildable and therefore competitive. The research is based on a case study of the design and production of long- span timber structures performed at a Swedish design company. The case study includes interviews, and a survey of 60 constructed long-span timber structures. A literature review of the industrialisation principles reveals that modularity has been a key concept in the evolution of the manufacturing industry. Therefore, the long-span timber construction industry should emit a bottom-up view where product modularity guides the construction processes. A systematic framework, Experience Feedback System (EFS), is created to store buildable construction knowledge based on modularity. The EFS is based on two distinct systems; Experience Based System (EBS), and Construction Knowledge Database (CKD), connected by a feedback loop for buildable construction feedback. The EBS utilises neural network theory containing competitive knowledge and experience of long-span timber structures, providing aid in early design. The CKS is based on the Design Structure Matrix (DSM), providing management of innovative construction and aid in detailed design. Due to the adaptability of neural networks and the developed 3-D DSM hierarchy representing the structural system, the systematic framework is potentially useful for the design and development of other types of structures and materials choices in the future.<br>Godkänd; 2004; 20070128 (ysko)

Rapidly assembled tent structures are temporary enclosures used to house people or goods. Their uses vary to include recreation, refugee housing, and military shelters. The structural concepts applied in these shelters are as variable as their uses. Some make use of a tensioned fabric and pole system to provide structural strength. Others have a load-bearing frame with attached fabric skin. Further variants make use of inflatable arches or consist of modular containers. Analysis of a number of different types of rapidly assembled tent structures reveals an area where innovation can occur. Conflicts in the last ten years suggest that rapidly assembled shelters for both military purposes and humanitarian relief have the greatest need for innovative solutions. Existing shelters used by the military lack the versatility and speed of deployment necessary in modern conflict. The lack of scalability in the designs makes it difficult to use an existing tent in different situations. They are slow to construct, heavy, and difficult to transport in large numbers. These problems suggest that there is a need for new shelters that better meet the needs of the military. The application of deployable structures technology meets military's needs for structures with the advantages of a small compacted volume, rapid assembly, and ease of deployment. This makes them ideal for application to shelter structures. The aim of this dissertation was to develop a new type of deployable, long-span shelter frame based upon tiled Bennett mechanisms. An overlapping combination of equilateral Bennett mechanisms yields a structure that opens into a half-cylinder shape, providing an enclosed space useful and applicable to the problem of deployable shelters. The specific application considered in the design portion of this process will be a long-span deployable shelter capable of housing military helicopters. This report details the development of the Bennett Shelter concept. Its deployed and compacted geometries are explored, and a procedure for determining structural properties and dimensions is presented. The full concept for the structure, from outer covering to foundation support is then detailed. Loads affecting the structure are determined, and the process of modelling and analysing the structure is then considered. Optimisation of the structure with respect to weight and serviceability requirements is conducted using a number of different materials, and full analysis of the optimal geometries is completed. As no method exists for evaluating the effect of imperfections on the deployment of overconstrained mechanisms, a procedure is derived. The effects of manufacturing imperfections on deployment of the Bennett mechanism are then explored using the method. A full examination of the variation of energy within the Bennett Shelter during deployment provides valuable insight into the performance of the structure. With the above analysis complete, it is shown that the Bennett Shelter is viable as a long-span deployable shelter.

Master of Science<br>Department of Civil Engineering<br>Robert J. Peterman<br>Concrete box culvert floor slabs are known to have detrimental effects on river and stream hydraulics. Consequences include an aquatic environment less friendly to the passage of fish and other organisms. This has prompted environmental regulations restricting construction of traditional, four-sided box culvert structures in rivers and streams populated by protected species. The box culvert standard currently used by the Kansas Department of Transportation (KDOT) is likely to receive increased scrutiny from federal and state environmental regulators in the near future. Additionally, multiple-cell box culverts present a maintenance challenge, since passing driftwood and debris are frequently caught in the barrels and around cell walls. As more structures reach the end of their design lives, new solutions must be developed to facilitate a more suitable replacement. Since construction can cause significant delays to the traveling public, systems and techniques which accelerate the construction process should also be considered. This thesis documents development of a single-span replacement system for box culverts in the state of Kansas. Solutions were found using either a flab slab or the center span of the KDOT three-span, haunched-slab bridge standard. In both cases, the concrete superstructure is connected monolithically with a set of abutment walls, which sit on piling. The system provides an undisturbed, natural channel bottom, satisfying environmental regulations. Important structural, construction, maintenance, and economic criteria considered during the planning stages of bridge design are discussed. While both superstructural systems were found to perform acceptably, the haunched section was chosen for preliminary design. Rationale for selection of this system is explained. Structural modeling, analysis, and design data are presented to demonstrate viability of the system for spans ranging from 32 to 72 feet. The new system is expected to meet KDOT’s needs for structural, environmental, and hydraulic performance, as well as long-term durability. Another option involving accelerated bridge construction (ABC) practices is discussed.

ABSTRACT THE PERFORMANCE OF MEDIUM AND LONG SPAN TIMBER ROOF STRUCTURES: A COMPARATIVE STUDY BETWEEN STRUCTURAL TIMBER AND STEEL ERTASTAN, Evren M.S, in Building Science, Department of Architecture Supervisor: Assoc. Prof. Dr. Erc&uuml<br>ment ERMAN December 2005, 174 pages This thesis analyzes the performance of structural timber and steel in medium and long span roof structures. A technical background about roof structures including structural elements and roof structure types, span definitions, and classification of roof structures are discussed. Roof structures are detailed with traditional and the contemporary forms. The thesis comprises the comparison between structural timber and steel by using structural, constructional and material properties. Structural forms and the performance of timber and steel are discussed. The research also includes the roof structures built with structural timber in Turkey, application, marketing and examples in Turkey are indicated. In the conclusion part the performance criteria of timber and steel are summarized, the researcher has prepared a table to compare the performance of timber and steel. Keywords: Timber, Steel, Roof, Structure, Span

Thesis (M.A. in Security Studies (Homeland Security and Defense))--Naval Postgraduate School, December 2008.<br>Thesis Advisor(s): Bergin, Richard. "December 2008." Description based on title screen as viewed on February 2, 2009. Includes bibliographical references (p. 117-131). Also available in print.