Study of construction methodology and structural behaviour of fabric-formed form-efficient reinforced concrete beam
Lee, Sang Hoon
The nature of this research is in advancing conventional structures and their methods of construction by exploring new technology. The formwork construction of the modern concrete structure involves the use of rigid materials such as steel and timber. This type of formwork often produces structures of forms with limited flexibility which would also hinder the even distribution of the induced stresses. To construct concrete structures with more organic forms; ones that responds to a more natural flow of the induced stresses, it is thought to be more logical to use flexible mould such as the fabric formwork. In such form-active shape the materials’ utilization can be maximized and the degree of material waste can be reduced. For example, when the form responds to the externally applied loads in the way that the internally incurred stresses at any point of the body closely match the capacity of the material, then the form is material-efficient and said to be in its optimal form. The use of fabric formwork, due to its permeability can also improve the quality of concrete by eliminating any air holes on the surface, and also there are reports showing the increase in concrete’s compression strength due to the reduction in water-cement ratio when cast in a fabric mould. This research concentrates on finding such material-efficient form (thus more sustainable) for reinforced concrete beam of improved material quality, through the development of the more efficient construction system of flexible fabric formwork. For this research 11 different types of beams have been built and tested in total, and their construction methods are illustrated and discussed also (Chapter 7 and Chapter 4 respectively). The designs of the beams are developed through consecutive experiment, analysis, evaluation, and modification process (Chapter 6). For the structural analysis of the beams, the most widely accepted analysis methods are reviewed and adapted (Chapter 8). Based on the evaluations of the analytical results the following variables of the beams are modified through the development of the beam designs: The effect of Compression Steel Mesh in Flange Stress Distribution Around Anchorage; Vertical and Horizontal Web Geometry Varying Depth of Flange Steel Content Also it is a part of the current research’s aim to look at the possible application of the current design methods for the design of the fabric formed beams that are discussed in this research. Thus the experimental results are compared with the results which are calculated from the standard design methods suggested by the British Standard Code of Practice (BS8110) (Chapter 9). Computational finite element (FE) analysis is carried out where more intensive analysis is required (Chapter 10). The results of the FE analysis are also compared with the theoretical and experimental results for the verification purpose. The material efficiency of the beam in its final form is assessed through the embodied energy analysis, which compares the total embodied energy consumed through the construction of the beam with a virtual beam that is designed in accordance with the BS8110 (Chapter 11). The analysis indicates that the total embodied energy of the fabric formed beam is about 20~40% less in comparison with the beam designed in accordance with the BS8110. This thesis has the purpose to illustrate and provide the practical information on the design and the construction process of the fabric formed beams, which can be used as a reference to the future research and construction.