D e v e l o p m e n t o f C o n f i g u r a t i o n of T r a n s v e r s e R e i n f o r c e m e n t
655
Details of Specimen and Experimental Method
A total of 4 specimens were cast as shown in Table 3 to assess the flexural capacity of a
reinforced concrete column according to the type of aggregate and
configuration of
transverse reinforcement. It was designed to have a shear span ratio of 3.0 allow anti-
symmetric flexure moment in the experiment section and to test the flexural failure.
As shown in Fig. 3, the cross-section of the experiment section was designed with a
dimension of 250x250mm with the height of the experiment section being 1,500mm. As for
the transverse reinforcement, it was designed as an H-type, the existing hoop steel bar
configuration, and as an S-type, a spiral steel bar configuration proposed in previous
studies, as shown in Fig. 3. In order to ensure a volumetric ratio of transverse
reinforcement of 1.2% for both the H-type and S-type, the transverse reinforcement
spacing was set at 63.3mm for the H-type and 45.3mm for the S-type. As for the amount
of
transverse
reinforcement in the experiment section, it was lower in the S-type specimen
than in the H-type specimen by approximately 50%.
As for the names of the specimens shown in Table 3, H represents the H-type specimen,
whereas S represents the S-type specimen. With respect to the type of aggregate used,
the specimen fabricated using natural aggregate is represented as AN and the specimen
fabricated using electric arc furnace oxidizing slag aggregate is represented as AS. Strain
gauges were attached on the longitudinal reinforcement and transverse reinforcement on
both ends of the experiment section the maximum moment as shown in Fig. 2 to measure
the modulus of strain on the steel bars.
In order to simulate an actual stress condition of reinforced concrete column, a constant
axial load (434kN) was exerted, after which two cycles of lateral load were repeatedly
exerted based on the yielding displacement of the longitudinal reinforcement. A 200-mm
displacement gauge was installed in a lateral direction in the experiment section to
measure
the displacement of the specimen in the lateral direction. The experiment was concluded
when the lateral load decreased to less than 85% of the maximum load.
Results
Flexural Moment versus Displacement Relationships
The hysteresis curve of the flexural moment-displacement of the specimens is shown in
Fig. 3. As shown in the figure, all specimens showed a ductile failure mode after flexural
yielding of the longitudinal reinforcement. Regardless of the configuration of the transverse
reinforcement, specimen AS, fabricated using electric arc furnace oxidizing slag aggregate,
showed the same maximum moment as specimen AN, fabricated using natural aggregate.
Also, regardless of the type of aggregate, the S-type specimen had the same maximum
moment as the H-type specimen even though the amount of transverse reinforcement was
reduced by more than 50%. The analysis of the cross-sections of the specimens in
accordance with ACI318-11 showed that the maximum flexural moment satisfied the ACI
standards and the results are summarized in Table 4.
