Design method development and software implementation for fibre-reinforced concrete slabs-on-ground

Mudge, Frederik Jacobus (2017-12)

Thesis (MEng)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: Ground-supported concrete slabs are common structural elements, used for a multitude of purposes. In industrial flooring applications, slabs-on-ground (SOG) are often subjected to severe loads, concentrated at points or acting over extended areas. Adequate reinforcement of such slabs is essential to obtain sufficient load capacity and to guarantee serviceability of a slab throughout its lifetime. Synthetic fibre reinforcement has been shown to be effective in increasing the tensile strength and toughness of concrete slabs-on-ground. It increases the load capacity of slabs without requiring procurement of costly steel-mesh, the labour associated with installing it, or major alterations to concrete mix design. Although extensive research has been carried out to analyse and predict the performance of synthetic-fibre reinforced concrete (SynFRC) slabs-on-ground, no universally accepted design guideline exists. Similarly, no computer-based design packages that facilitate the analysis and design of such slabs are available. In this study a comprehensive set of algorithms is developed for the analysis and design of SynFRC ground-supported slabs. It includes an algorithm that can optimise any given slab design in terms of cost. The proposed algorithms are based on an extensive review of relevant academic and industrial literature pertaining to SynFRC, slabs-on-ground and their associated design approaches. Long term settlement and the bearing capacity of soil are not accounted for. The reaction of soil to slab loading is included by means of a modulus of subgrade reaction, k. The yield-line approach to assessing point load capacities is adopted, while elastic methods are employed to analyse the effect of line- and uniformly distributed loads on the structure. A software prototype that implements the algorithms and provides a user friendly interface is developed using the Java programming language. It includes various features which aid the process of modelling a slab, such as the generation of the most adverse wheel loads within a traffic zone. To ensure the validity of all algorithms and their implementation, a series of unit tests and validations are carried out. It is concluded that the proposed algorithms and software prototype operate successfully and yield useful results.

AFRIKAANSE OPSOMMING: Grondgesteunde betonblaaie is algemene struktuurelemente wat vir 'n verskeidenheid doeleindes gebruik word. In industriële vloertoepassings word grondgesteunde betonblaaie dikwels aan relatief hoë belastings blootgestel. Die belastings kan in die vorm van gekonsentreerde puntlaste of verspreide laste oor ʼn area wees. Geskikte versterking van sulke blaaie is noodsaaklik om voldoende laaikapasiteit te verkry en die diensbaarheid van 'n blad te verseker oor die leeftyd daarvan. Dit is al bewys dat sintetiese veselversterking effektief is om die treksterkte en taaiheid van betonblaaie op die grond te verhoog. Dit verhoog die laaikapasiteit van blaaie en skakel die voorsiening van staal maas versterking, teen ʼn relatief hoë koste met die arbeid geassosieer met die installering daarvan, of groot veranderinge aan betonmengselontwerp uit. Alhoewel uitgebreide navorsing al gedoen is om die gedrag van sintetiese veselversterkte betonblaaie op die grond te analiseer en te voorspel, bestaan daar geen universeel aanvaarde ontwerp riglyn nie. Daar is ook geen rekenaargebaseerde ontwerppakkette wat die ontleding en ontwerp van sulke blaaie ondersteun nie. In hierdie studie word 'n omvattende stel algoritmes ontwikkel vir die analise en ontwerp van sintetiese veselversterkte grondgesteunde betonblaaie. Dit sluit 'n algoritme in wat 'n gegewe bladontwerp in terme van koste kan optimeer. Die voorgestelde algoritmes is gebaseer op 'n uitgebreide oorsig van relevante akademiese en industriële literatuur met betrekking tot veselversterkte beton, betonblaaie op die grond en hul gepaardgaande ontwerpbenaderings. Langtermyn versakking en die evalueer van die dravermoë van die grond ondersteuning word nie in hierdie studie in ag geneem nie. Die reaksie van grond tot bladbelasting word ingesluit deur middel van 'n stutlaag reaksiemodulus, k. Die sogenaamde “yield-line” benadering vir die assessering van puntladingkapasiteite word aangeneem, terwyl elastiese metodes gebruik word om lyn- en uniform verspreide laste te analiseer. ʼn Prototipe rekenaar toepassingsprogram, wat die algoritmes implementeer en 'n gebruikersvriendelike koppelvlak voorsien, word ontwikkel met behulp van die Java programmeringstaal. Dit bevat verskeie eienskappe wat die modellering van 'n blad vergemaklik, soos die opwekking van die mees ongunstige wielbelastings in 'n verkeersone. Om die geldigheid van al die algoritmes en hul implementering te verseker, word 'n reeks eenheidstoetse en validasies uitgevoer. Daar word tot die gevolgtrekking gekom dat die voorgestelde algoritmes en prototipe rekenaar toepassingsprogram suksesvol werk en nuttige resultate lewer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/102721
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