Parametric Study of Reinforced Concrete Deep Beams with Rectangular Web Openings Subjected To a Static Monotonic Loading
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Date
2020-07
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Addis Ababa University
Abstract
Transverse openings in beams are usually present in building, they are provided for the purpose
of allowing the passage of service lines such as sanitary pipes, electric cable ducts, air
conditioning ducts and telephone lines. The presence of web openings in beams tends to reduce
the flexural and shear strength of the beams. Effect of such openings may even be more
dangerous in reinforced concrete deep beams, because deeps beams like transfer girders where
the column is directly supported on them, are in general subjected to a very large concentrated
load. Since different building codes do not give any provisions regarding RC deep beams with
transverse web openings and the effect of parameters like degree of interruption of natural load
path, openings size, Aspect ratio of opening sides and compressive strength of concrete on the
behavior of such types of beams have not been investigated thoroughly. This research attempts to
study the effects of the above-listed parameters using a finite element software VECTOR. In the
first portion, the finite element model of a Test beam is validated and verified using the results of
an experimental test. Results shows that the software accurately predicts the maximum deflection
and failure load of the test beams. The error obtained for both cases where under 5%, which is
does not exceed the minimum specified tolerance. After the finite element model was validated,
a total 73 of numerical simulation were conducted in an attempt to investigate each of the
parameters mentioned earlier. The output parameters that was interest to this research was failure
load of the test beams, maximum mid span deflection of the beams, cracking load and the
maximum crack width. Results showed that, when openings are placed within the shear span of
the beam, as the degree of interruption of the natural load path and opening size increases, the
failure load (shear strength) of the beams drastically decreased and strength reduction as high as
95% were observed. However, when openings were placed within the flexural region, failure
load of the beams were almost similar to the failure loads of the solid beams without web
openings but a considerable increase in deflection as high as 39% was obtained. In addition, the
magnitude of cracking load decreased when the size of openings located within the shear span
increased. Furthermore, results indicate that, increasing the concrete compressive strength will
only be effective in counteracting the strength loss due to web openings when the openings are
small (i.e. opening area < 8.59% of the shear span area). For large openings, increasing the
concrete grade will have insignificant effect on failure load (shear strength of the beam).
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Keywords
einforced Concrete Deep Beams, Parametric Study, Static Monotonic Loading