PSI - Issue 64

Nima Kian et al. / Procedia Structural Integrity 64 (2024) 1049–1056 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1055

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(a)

(b)

Fig. 8. a) Backbone envelopes of lateral load-displacement curves, b) Cumulative energy dissipation (CED).

Thus, corresponding displacements and strains to the performance levels are enhanced for specimen RS with respect to specimen S, fulfilling the requirement of TBEC (2018). Moreover, it is deduced that specified strain limits in TBEC (2018) could estimate the performance of the substandard, retrofitted, and code-compliant specimens sufficiently well. By comparing the specified performance limits in Figure 9 for specimen S, it can be said that TBEC (2018) is still reliable on the estimation of performance level of substandard columns as well.

Fig. 9. Backbone envelopes of lateral load-displacement curves (Pushing). Table 5. Concrete strain, lateral load, and lateral displacement of specimens corresponding to performance levels. ×10 −6 L (kN) (mm) Drift (%) C SH 1250 88.0 4.5 0.45 KH 7180 154.5 14.9 1.50 GO 9580 150.0 20.0 2.00

SH KH GO SH KH GO

2100 6100 8100 4000 6900 9000

93.0 100.1 104.9 133.1 147.0 153.7

5.5 7.0 8.3

0.55 0.70 0.83 1.50 2.30 2.80

S

14.9 23.0 28.1

RS

4. Conclusions This work has presented the development of numerical models to better capture cyclic performance of previously tested RC columns subjected to high axial load in combination with high shear demand. To address this, three previously tested specimens consisting of one substandard, one code-compliant, and one CFRP-retrofitted specimens were considered as specimens to be modeled numerically. Employing some failure mechanisms such as buckling features of rebars govern the experimental results and consideration of strain penetration through a rotational spring adds up more effort in numerical modeling. The observed failure mechanism as well as overall behavior of substandard columns in experiment are reflected in the numerical analyses conducted in ATENA and OpenSees. Accuracy of numerically reproduced models were validated by comparing with test results in terms of hysteretic and backbone load-displacement curves, CED, and specified performance levels proposed in TBEC (2018). Both numerical models showed sufficiently good agreement with the experimental results. The following major conclusions can be drawn from this limited work: