EFFECT OF REINFORCEMENT DETAILS ON CONFINEMENT ON REINFORCED

CONCRETE COLUMNS Department of civil engineering and applied mechanics, McGill University, Montreal, Canada

INTRODUCTION Four full-scale reinforced concrete columns were constructed with different

confinement reinforcement details and were tested in pure axial loading. The

purpose was to determine the influence of the degree of confinement. One

specimen was constructed without any concrete cover to determine the

influence of the spalling of the concrete cover during loading.

SPECIMENS DETAILS :

4 COLUMNS; 3 DIFFERENT DESIGNS

REINFORCEMENT DETAILS

LONGITUDINAL REINFORCEMENT:

8-15M reinforcing bars

• db = 16mm

• As = 200mm2

TRANSVERSE REINFROCEMENT:

10M hoops

• db = 11.3mm

• As = 100mm2

RESULTS The normalized stress-strain plots were used to compare the response of columns.

The plots showed how an increased degree of confinement can significantly

improve the performance of concrete.

Fig. 1: Reinforcement details for

A, B and C specimens and

transverse reinforcement details

with 30mm cover

12

00

mm

12

00

mm

12

00

mm

A B C

8-15M

400mm

22

5m

m

CONCLUSIONS Closely spaced hoops provide better confinement than widely spaced hoops.

Bar buckling is more visible in columns with larger hoop spacing which leads to

premature cover spalling.

Table 1: details of specimens

Heidy Jasmid Botero Villegas ; Supervisor: Professor Denis Mitchell

Better performance and post peak

response for specimen C compare to

specimens A and B.

Fig.2: Specimens Anc ,A,B and C at failure and (a) bar buckling of specimen Anc

(b) close up of confinement reinforcement of specimen C

Anc C B A (a) (b)

Influence of cover apparent in

specimen A