Creep and shrinkage prediction models for concrete water retaining structures in South Africa

[摘要] ENGLISH ABSTRACT: Concrete water retaining structures (WRS) in South Africa are under scrutiny due tothe numerous durability problems that they have experienced lately; despite theefforts by local and national authorities in conserving these structures. At the heart ofthese problems are the creep and shrinkage phenomena. While shrinkage is thereduction of concrete volume with time, creep is defined as the time-dependentincrease of concrete strain under constant or controlled stress. Both phenomena areaffected by conditions to which WRS are exposed hence their accurate prediction isrequired.Numerical models have been developed to calculate the extent to which concretecreeps or shrinks over time. The objective of this thesis is to identify which of thesemodels is better equipped to be used in South African WRS design. This is achievedthrough a systematic method that involves an investigation into the contents of thesemodels and a statistical comparison of model calculations to WRS representativedata.In partnership with reputable universities, a pioneer experimental creep andshrinkage data base is created in this project from which the WRS related data isselected. While investigating the contents of the numerical models, their applicabilityto South African WRS is identified and the integrity of model contents is assessed.Indeed, a few irregularities are found in the process and are presented in this thesis.The model calculations are statistically compared to data in the form of individualexperiments as well as in the form of groups of experiments with similar concretes tofind the ideal prediction model for different types of concretes as well.Also pioneered in this project is a weighted criteria and point system in which thefindings of the model content assessment and statistical evaluations areincorporated. It is based on this system that conclusions are drawn and the mostsuitable prediction model for WRS design in South Africa is selected.

[发布机构] Stellenbosch University