Active confinement of weakened concrete columns

Effect Of Pre-Tensioned Level on Axial Stress-Strain Behaviour of Confined Concrete: A Review

“…This implies that the initial stiffness of confined concrete is not affected by pre-tensioned level. This was also reported in other research [10,12,14]. In passively confined concrete, the pre-peak stress-strain curve shows that stiffness degradation occurs relatively earlier than actively-confined concrete.…”

“…This has been proven experimentally from previous research [7,14]. It was found that the amount of pre-tensioned level affects the stress-strain behaviour of confined concrete [7,8,10,[12][13][14]. A comparison between confined concrete with and without pre-tensioned force is illustrated in Fig.…”

“…In [14], it was found that increasing the pre-tensioned level improved the peak stress and peak strain of confined concrete. However, increasing the pre-tensioned level too much resulted in reduction of both peak stress and peak strain as shown in Fig.…”

“…This resulted in certain degree of inaccuracy of the expressions to predict the peak point of the confined concrete. Although [14] considered the pre-tensioned confining pressure into the expression by adding the pre-tensioned confining pressure into f l , the expression overestimated the peak strain up to 70 %. This indicates that the sum of pre-tensioned confining pressure to f l is not suitable to predict the peak strain of confined concrete.…”

“…This type of confinement is known as active confinement while confinement without such confining pressure is known as passive confinement. In recent years, research on active confinement has been increasing [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Hence, the understanding of pre-tensioned mechanisms becomes important.…”