Four-dimensional design, analysis and construction of a precast concrete pilot house

Abstract

This research entails the construction and overall structural analysis of a precast concrete pilot house. The house is constructed under the principles of Four- Dimensional (4D) design proposed by Hendrickx and Vanwalleghem (Hendrickx, 2002), in which basic elements are developed and an assembly criterion is adopted for construction. This work seeks to introduce the principles of 4D design into concrete construction to realize sustainable use of resources and qualitative use of the concrete constructions. The principles include; design for dismantling where materials are made to be technically separable, design for deconstruction where the components of the construction are made to be such that they can be disassembled and, design for adaptability in which the construction is made such that it is capable of adapting to emerging changes in user requirements (Debacker et al, 2007). The basic concrete elements developed in this research include columns and beams both of dimensions 80mm*80mm*1024mm, slab panels of dimensions 512mm*1024mm*24mm and connector cubes as cubic elements of sides 80mm. The assembly criteria adopted involve dry connection via bolts and nuts and embedded steel plates. Columns and beams are connected via the connector cubes to form a framework onto which double slab panels are anchored from the interior and the exterior wall elements respectively and connected by bolting via anchor plates embedded in the slab panels. Structural analysis of the construction was done at two levels akin to the construction stages; first upon assembly of elements to the window level and second, upon complete assembly of elements to the lintel level and the roof. The analyses were done under respective loads acting on the structure primarily dead loads and wind loads at each construction stage. The structure was modelled and analysed using SCIA Engineer software to simulate the behaviour of the structure under loading, to perform checks and to design the elements. The results of the analyses done and the completion of the pilot house construction demonstrated that the designed elements could satisfactorily be used to develop single storey precast concrete houses of up to 3m in span without partition walls while providing numerous configuration possibilities where partition walls are introduced. The cost analysis was done and showed that the pilot house costs about 30% higher than a typical masonry brick and mortar house of equal dimensions but the fact about cost saving by mass production, the advantages of disassembly, reconfiguration possibilities and demolition without wastes makes the construction technology more beneficial. Further to this, a more detailed design and analysis of the connections is being done by a colleague student Kipkemoi Ng’eno to assess the internal forces developed, determine optimal sizes and remove redundancies in the connection provisions. It is recommended that the possible use of single panel system for internal walls be investigated to further ease assembly process and ultimately lower the cost of construction under the 4D design technology. Finally, more research needs to be done on the development of alternative and cheaper connection systems.