Average reinforcement strain in reinforced concrete structures loaded until failure - An experimental study on the effect of reduced interaction and reinforcement ratio on plastic deformation capacity
Typ
Examensarbete för masterexamen
Program
Structural engineering and building technology (MPSEB), MSc
Publicerad
2021
Författare
Nozad, Arghavan
Moa, Steiner
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Reinforced concrete and its behavior have a significant role in structural engineering.
Reinforced concrete structures are usually designed based on Eurocode for
static loading which is not sufficient in case of dynamic loading situations such as
explosion. For a structure subjected to impulse loading, plastic deformation capacity
is of higher importance rather than the load capacity. The regulations provided
by the Swedish Fortification Agency, FKR 2011, provides certain design regulation
to fulfill requirements for structures subjected to impulse load. According to these
regulations for which a revision is needed, average tensile strain of reinforcement at
failure is an effective factor representing plastic deformation capacity.
The aim of this project was to study the effect of reinforcement amount and decreased
interaction between steel and concrete on reinforcement average strain and
plastic deformation capacity of reinforced concrete beams subjected to static loading.
Therefore, nine beams in three different categories were constructed and subjected
to a four-point bending test as: three beams with 10 reinforcement, three beams
with 12 reinforcement, and three beams with 12 reinforcement with PVC tubes
placed in the middle of the reinforcement to decrease the bond. The number of bars
and the dimensions were the same for all beams. Before casting, the reinforcement
were marked every 50 mm and then remove after testing to measure the elongation
of the bars. Also some bars were 3D scanned as another method to measure the
elongation and to analyse the cross-sectional changes. During the tests, the structural
response of beams was recorded using Digital Image Correlation (DIC).
Although there were some scatter in test results, in general it can be concluded
that beams with 12 reinforcement provided a larger plastic deformation capacity
compared to beams with 10 reinforcement. Also, application of PVC tubes to
reduce the bond between the concrete and the steel resulted in a larger plastic
deformation capacity and average reinforcement strain. The utilization rate for
strain values was estimated and the reinforcement bars with PVC tubes showed a
increase utilization rate.
Beskrivning
Ämne/nyckelord
Reinforced concrete, plastic deformation capacity, average tensile strain , bond interaction, DIC, four-point bending test, FKR