Table 7 Hardening strategies corresponding to different failure probabilities and disaster intensities

Level 2

\(L_{1 - 2}^{e}\), \(L_{6 - 26}^{e}\), \(L_{1 - 2}^{g}\), \(P_{8 - 9}^{g}\), \(L_{2 - 4}^{h}\), \(L_{14 - 15}^{h}\)

\(L_{1 - 2}^{e}\), \(L_{6 - 7}^{e}\), \(P_{1 - 2}^{g}\), \(P_{8 - 9}^{g}\), \(L_{2 - 4}^{h}\), \(L_{14 - 15}^{h}\)

\(L_{1 - 2}^{e}\), \(P_{6 - 7}^{e}\), \(L_{27 - 28}^{e}\), \(L_{28 - 29}^{e}\), \(L_{8 - 9}^{g}\), \(L_{28 - 31}^{h}\)

Level 3

\(L_{1 - 2}^{e}\), \(P_{6 - 7}^{e}\), \(L_{27 - 28}^{e}\), \(P_{8 - 9}^{g}\), \(L_{11 - 13}^{h}\), \(L_{14 - 15}^{h}\)

Level 4

\(L_{1 - 2}^{e}\), \(L_{6 - 7}^{e}\), \(P_{8 - 9}^{g}\), \(P_{9 - 10}^{g}\), \(L_{2 - 4}^{h}\), \(L_{14 - 15}^{h}\)

\(L_{1 - 2}^{e}\), \(L_{6 - 7}^{e}\), \(P_{8 - 9}^{g}\), \(P_{9 - 10}^{g}\), \(L_{11 - 13}^{h}\),\(L_{14 - 15}^{h}\)