Chin, Mei Yun
(2014)
Shear resistance of oil palm shell concrete beams with and without shear reinforcement.
PhD thesis, University of Nottingham.
Abstract
In recent years, the use of Oil Palm kernel Shell (OPS) aggregate as coarse aggregate in concrete has received increasing attention due to its environmental and economic benefits. To date, considerable amount of research have been carried out to aid the understanding of its concrete mixture designs and its material properties, but, only limited amount of works have been carried out to aid the current understanding with respect to its shear resistance.
The main objective of this research was to investigate the shear resistance of Oil Palm kernel Shell Concrete (OPSC), and to compare with the conventional Normal Weight Concrete (NWC) through experimental and analytical study. The experimental work carried out in this research involved destructive testing of forty-five numbers of beam specimens, of which twenty-nine beams (24 casted with OPSC and 5 casted with NWC) were casted without shear reinforcement while the remaining sixteen beams (11 casted with OPSC and 5 casted with NWC) were casted with shear reinforcement. The main variables for beams casted without shear reinforcement were the concrete strength (fcu), overall section depth (h), longitudinal reinforcement (ρ), and span to depth ratio (a/d). Whilst the main variables for beams casted with shear reinforcement were concrete strength (fcu), shear reinforcement (ρs) and inclination of shear cracks (Θ).
For beams casted without shear reinforcement, three distinct failure mechanisms were observed from the tests: the shear compression mechanism (associated with a/d < 2.5); the diagonal tension mechanism (associated with a/d = 2.5 and ρ = 0.88%); and the shear mechanism (associated with a/d ≥ 2.5 and ρ > 0.88%). Whilst for OPSC beams casted with shear reinforcement, shear compression failure was observed for the tests.
A comparative study was carried out to investigate if there are any differences on the ultimate shear resistance and the shear failure mechanism between the OPSC beams and NWC beams. In general, all specimens (OPSC and NWC) were found to fail in similar failure mechanism; however, some variations have been noted in the ultimate resistance with respect to span to depth ratio, concrete strength, and longitudinal steel ratio (for beams without shear reinforcement) and concrete strength (for beams with shear reinforcement).
An analytical study was carried out using the upper bound approach to evaluate the observed shear failure mechanisms, and hence, to predict the failure loads. A theoretical model was developed for each of the casting condition. In addition, design models based on Eurocode 2 (EC2) and BS8110 have been developed. In all cases, the proposed models achieved good agreement with the test results.
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