PSI - Issue 52

Rakesh Katam et al. / Procedia Structural Integrity 52 (2024) 72–88 Rakesh Katam/ Structural Integrity Procedia 00 (2019) 000 – 000

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on concrete grade caused by rising reinforcement, and the required reinforcement under the current load conditions. In this instance, the failed columns are B1, B2, B4, C1, C2, and C3 shown in Fig. 9(b).

Table 9. Ast (mm 2 ) is required for different conditions. Column No. Strength reduction

No reduction

Existing (Ast)

A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4

689 605 552 552

552 552 552 552

679 679 679 679 679 679 679 679 679 679 679 679

2038 1998

1791 1708

695

552 622

1059 1724 1581 4139

1211 1134

552 552

753

In the third case, using the same M15 grade of concrete, we have reduced the proportion of rebar since, according to the NDT, there is a high chance of reinforcement being corroded. Therefore, we reduced the rebar percentage from 20% to 30%, and the column collapse is depicted in Fig. 9(c). A1, A2, A3, B1, B2, B3, B4, C1, C2, C3, and C4 are the columns that failed due to additional dead loads and degrading material strength.

Fig. 9. Columns failure (a) existing condition; (b) strength reduction in concrete; (c) strength reduction in both concrete and steel.