Browsing by Author "Shiso, Etobo Prince"
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- ItemIn-plane structural response of single-storey unreinforced walls constructed using alternative masonry units(Stellenbosch : Stellenbosch University, 2019-04) Shiso, Etobo Prince; De Villiers, Wibke; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Studies on alternative masonry units (AMUs) at Stellenbosch University seek to reduce the environmental impact that conventional masonry units (concrete masonry units [CMUs] and fired clay) cause, by developing masonry units that are environmentally friendly, socially acceptable and structurally sound. The introduction of AMUs in the construction industry as construction components for low-income housing depends on the determination of their minimum mechanical specifications. The three AMU types being investigated include compressed stabilized earth blocks (CSEBs), Adobe blocks, and alkali-activated concrete blocks (AACBs). Various experimental tests are being conducted in the laboratory on AMUs as well as concrete masonry blocks (CMUs), which aim to provide sufficient information on the technical performances of these masonry units. Further, as certain areas in South Africa have been identified to be at risk of low to moderate seismic activities, the South African loading code requires that single storey masonry structures be designed for seismic actions. To use AMUs as construction components for such structures necessitates, as part of the determination of mechanical specifications, that an investigation be carried out on the seismic behaviour of a masonry structure constructed with AMUs. Such investigation is often conducted in a laboratory setting by subjecting masonry walls of pre-defined geometry and with restraint, as in a structural building system, to similar loading conditions a wall would experience during an earthquake. In this study, in-plane shear-compression tests on large scale masonry wall, constructed with CMUs and AMUs respectively, are conducted to determine the in-plane structural response of these walls. This was achieved by designing and constructing an appropriate test set-up capable of undertaking such tests, and by manufacturing a large quantity of masonry units. Characterisation tests were performed on masonry units as well as wallets to determine their respective compressive strength and modulus of elasticity. Density tests were also performed on masonry units, the results of which are within the range of values provided in literature. Performed at various stages on the experimental programme and at different ages of masonry units, an increase over time in the strength and stiffiness was observed in the four different masonry units. While AACBs showed a higher compressive strength than the CMUs, they had a lower modulus of elasticity. On the other hand, the Adobe blocks had the lowest compressive strength and modulus of elasticity, and exhibited little increase of these properties over time. Difficulties were encountered while performing tests on masonry wallets as adequate boundary conditions were required at the top and bottom of the specimens. However, sufficient results were obtained which were used to determine the pre-compression levels applied on top of the wall specimens. Further, two test set-up configurations for the in-plane shear-compression tests were adopted based on the boundary conditions (BC) the wall was subjected to, i.e. fixed-free and fixed-fixed BC. The test results of AMU walls indicated that with the fixed-free BC, the specimen exhibited a rather large lateral capacity as compared to the results from a fixed-fixed BC configuration. Although difficulties were encountered while performing tests on CMU wall specimens, it was found that with few adjustments of the test set-up these tests could be performed successfully. Forming part of the technical performances of the masonry units, the results obtained and presented in this study can further be used in forthcoming studies for validation of numerical modelling and, ultimately, the determination of minimum mechanical specifications of AMUs.