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Producing steel causes 6% of global anthropogenic carbon dioxide emissions. Experts recommend that these emissions are reduced by half by the year 2050 in order to avert the worst consequences of climate change. Demand for steel is predicted to double in the next 36 years, meaning that a 75% reduction in emissions per unit of steel produced is necessary to reach the recommended limit. Process efficiency improvements cannot deliver this magnitude of reduction; however if steel is used more efficiently so that less new material is required to deliver the same service - a concept termed 'material efficiency' - then this could allow demand to be satisfied whilst emissions targets are achieved. Construction is the single largest use of steel globally, therefore using steel more efficiently in construction will reduce emissions. Three material efficiency strategies are identified as having most potential for this industry: using less material, using products for longer, and reusing components. In order to prioritise areas for research, steel flows into construction are mapped, finding that industrial buildings and utility infrastructure are the largest users of steel, while superstructure is confirmed as the main use of steel in a typical building. To estimate the potential to use less steel in buildings, 23 steel-frame designs are studied, sourced from three leading design consultancies. The utilisation of each element is found and the building datasets are analysed to infer the amount of steel over-provided. The results suggest that such buildings contain almost twice as much steel as necessary for structural performance, and indicate that this amount of over-provision occurs to minimise labour costs, which are a larger proportion of total costs than materials. To investigate how buildings and infrastructure could be used for longer, reasons for their failure are reviewed. Based on interviews with industry professionals a set of strategies is proposed, tailored to each failure cause and distinguishing between cases where failure can and cannot be reasonably foreseen. Steel sections could be reclaimed from old buildings and reused in new buildings but this does not occur because they are damaged during demolition. Designing for deconstruction would facilitate reuse but is not practised due to its cost. Data from interviews and a commercial working group are analysed to identify three aspects of designing for deconstruction that provide financial and operational benefits to clients, thus encouraging their use. One remaining technical barrier to deconstruction is composite steel-concrete systems, where welded connectors make it impractical to separate the steel beam from the concrete slab without damage. A novel bolted composite connector is proposed and tested in three beam experiments. The bolted connector allows successful separation of the components, facilitating reuse. Its structural performance is similar to that of welded connectors and can be predicted using current design standards. Each of the investigations reveals significant opportunities to reduce steel use in construction by using material more efficiently. Achieving these savings would reduce demand for new steel production and thereby decrease carbon dioxide emissions.

Appendix 6 of the ANSI/AISC 360-10 Specification provides methods for assessing the required stiffness and strength for basic bracing of columns and of beams. Substantial evidence exists showing that the Appendix 6 equations provide an accurate characterization of the stability bracing requirements, particularly when various refinements from the AISC Commentary are employed. Nevertheless, the development of these equations is based largely on elastic stability theory and various practical approximations are invoked to make the equations useful for design. Some of the important approximations relate to the handling of member inelasticity as well as the influence of member continuity across brace point locations. To the knowledge of the author, no comprehensive studies have been conducted to date to evaluate the specific nature of these approximations. Furthermore, the current Appendix 6 provisions do not recognize the benefits of combined lateral and torsional bracing. Limited prior research studies have shown substantial reduction in the demands on the individual bracing components by using them in combination. This thesis presents a methodical and comprehensive study of basic beam bracing behavior via refined FEA test simulation. Various point (nodal) lateral, shear panel (relative) lateral, point torsional, combined point lateral and point torsional, and combined shear panel lateral and point torsional bracing cases are studied for representative beams subjected to uniform bending. Detailed comparisons to the current Appendix 6 rules are provided, where applicable, and recommendations for improvements are forwarded. Specific questions addressed in this research are: • What is the effect of inelasticity on the bracing response and requirements? • What is the influence of member continuity across the brace points on the bracing response and requirements? • What are the benefits of combined torsional and lateral bracing when the lateral bracing is placed on the compression flange versus when it is placed on the tension flange.

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This thesis deals with the strength analysis of girders handling 186 t. The main objective of this thesis is to perform strength control using the Finite Element Method. NX I-DEAS software was used to perform all the necessary calculations. Possible design changes for undersized components are also presented.

Master of Science / Department of Architectural Engineering and Construction Science / Bill Zhang / Vibration has been a consideration in many types of structures, and as the advancement of technology has allowed steel and concrete sections to become lighter, vibration has become more of a consideration in the design of structures. This report focuses on occupant induced vibration of steel framed floors due to running as the vibration source. The history of vibration analysis and criteria in structures is discussed. However, lack of research and experimentation on running as the source of vibration exists; therefore, the history section focuses on walking as the source of vibration. The current design criteria for vibration of steel framed floors in the United States of America is the American Institute of Steel Construction (AISC) Design Guide 11: Vibrations of Steel Framed Structural Systems Due to Human Activity. This design guide discusses vibration due to walking, running, and rhythmic activities as well as gives design criteria for sensitive occupancies and sensitive equipment. In order to apply the Design Guide 11 analysis procedure for running as the source of vibration, the Kansas State University Chester E. Peters Recreation Complex is used as a case study. The recreation complex includes a 1/5-mile running track that is supported by a composite steel framed floor. Based on the Design Guide 11 criterion, the running track is deemed acceptable. Lastly, this report discusses remedial procedures in the case of annoying floor vibration specific to floors that have running as a source of vibration. In addition, areas of further research are suggested where running is a source of vibration on steel framed floors.

This paper focuses on illustrating the effectiveness of the new material model, 𝜏𝐵𝑇𝑅 in comparison with the Specifications for Structural Steel Buildings (2016) material model, 𝜏𝐴𝐼𝑆𝐶 , against a detailed finite element model to determine the accuracy of modeling the inelastic behavior of steel W-Shapes. A total of seven steel columns were analyzed, using a W8x31 section, and eleven benchmark frames to compare the performance of the two material models. An ultimate strength study was conducted using the following slenderness ratios, L/r, of 40, 60, 80, 100, 120, 160, and 200 and oriented such that minor-axis bending occurs. The benchmark frames were modeled under a limit load analysis to illustrate the magnitude of stiffness reduction considering both major and minor-axis bending. Lateral displacements were recorded and compared for the eleven frames up to the collapse condition. Additional information is provided discussing the capabilities of the two material models and their performance when compared to a detailed finite element model. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Delay is one of the most common problems in the steel construction industry. At the time of bidding steel contractors plan tasks and assign resources according to the site visits, the information given in the contract and specifications related with the project. However, as the project progresses some conditions of the work may change. These changes may affect originally planned means and methods. Finally, the affected activities cause the project total cost and duration to increase. In steel construction projects, if not managed properly in accordance with the contract, changes are likely to result in claims between the project participants. In this study, a delay analysis methodology which is based on time impact analysis is proposed. The aim of this methodology is to quantify impacts of work changes on the schedule and cost of steel construction projects and identify the responsible parties for these changes. A risk breakdown structure is presented to help decision-makers to identify probable sources of risk factors that usually result in time and cost overruns. The potential sources of change are categorized into 3 groups: contractor-related, owner-related and external factors. By using this structure, contractors may classify changes and assign the impacts of changes to the appropriate parties. The proposed methodology comprises of 3 steps: identification and quantification of delays, allocation of these delays to responsible parties and using TIA to calculate overall impact of changes on time and cost. The major benefits of this methodology are / a) its ability to handle and quantify changes in a step by step procedure, b) it provides a graphical representation of actual progress, and c) it helps decision-makers to give reliable decisions by monitoring the impact of changes during the project&amp / #8217 / s life cycle. Construction professionals may use it to apportion impact of changes in a systematic and reliable way. Moreover, reports generated by using this methodology can provide evidence during the claim management process. An application of this methodology on a steel project demonstrates the superiority of the process in explaining the dynamic nature of changes and in apportioning the impacts between different parties in a systematic way.