Figure 1:
(a) Isometric view and (b) Cross section of the building model
Figure 2:
Plan view of the building and the indication of the primary beams for (a) 1st-10th floor and (b) 11th-13th floor
Figure 3:
Cross sections of the building and indication of column dimensions
Figure 4:
Reinforcement detail of the RC columns
Figure 5:
Reinforcement detail of the primary RC beams
Table 1:
Site soil profile
| Depth | di (m) | Ni (N-SPT) | di / Ni |
|---|---|---|---|
| 1 | 1 | 4 | 0.25 |
| 2 | 1 | 1.67 | 0.6 |
| 3 | 1 | 0.83 | 1.2 |
| 4 | 1 | 0.56 | 1.8 |
| 5 | 1 | 0.56 | 1.8 |
| 6 | 1 | 3.5 | 0.29 |
| 7 | 1 | 7 | 0.14 |
| 8 | 1 | 8 | 0.13 |
| 9 | 1 | 9 | 0.11 |
| 10 | 1 | 10 | 0.1 |
| 11 | 1 | 10 | 0.1 |
| 12 | 1 | 11 | 0.09 |
| 13 | 1 | 11 | 0.09 |
| 14 | 1 | 12 | 0.08 |
| 15 | 1 | 13 | 0.08 |
| 16 | 1 | 13 | 0.08 |
| 17 | 1 | 14 | 0.07 |
| 18 | 1 | 18 | 0.06 |
| 19 | 1 | 22 | 0.05 |
| 20 | 1 | 22 | 0.05 |
| 21 | 1 | 22 | 0.05 |
| 22 | 1 | 19 | 0.05 |
| 23 | 1 | 18 | 0.06 |
| 24 | 1 | 18 | 0.06 |
| 25 | 1 | 19 | 0.05 |
| Total | 25 | 7.42 |
Figure 6:
Spectral response of the site under study for earthquakes with 250, 1000, and 2500 years of return period
Figure 7:
Configuration of the LRB isolators at the base of the building
Table 2:
LRB isolator properties
| No | Isolator parameters | LRB Interior | LRB Exterior |
|---|---|---|---|
| 1 | Isolator type | LH100G4-K | LH095G4-K |
| 2 | Maximum vertical load, Pmax (kN) | 9454.81 | 8110.73 |
| 3 | Bearing diameter, DB (mm) | 1000 | 950 |
| 4 | Lead plug diameter, DL (mm) | 250 | 240 |
| 5 | Total thickness of rubber, Tr (mm) | 201 | 198 |
| 6 | Rubber shear modulus, Gr (MPa) | 0.385 | 0.385 |
| 9 | σload (MPa) | 12.84 | 12.22 |
Figure 8:
(a) 3D isometric view, and (b) lateral-section of LRB isolator (Source: ISOSISM®)
Figure 9:
Schematic bilinear model of the LRB isolators
Table 3:
Bilinear model parameters of the isolators
| No | Model parameter | LRB interior | LRB exterior |
|---|---|---|---|
| 1 | Vertical stiffness, Kv [kN/m] | 4.61×106 | 4.21×106 |
| 2 | Initial stiffness, Ki [kN/m] | 18083 | 16579 |
| 3 | Yield force, Fy [kN] | 423.67 | 390.45 |
| 4 | Post yield stiffness ratio, KP/ Ki | 0.0769 | 0.0769 |
Figure 10:
Schematic curvature-moment relationship model as per ASCE 41-17
Figure 11:
Representative spring models to consider the SSI effect in SAP 2000
Table 4:
Summary of soil spring parameters for SSI modelling
| Depth [m] | N-SPT | Deformation modulus | α | Horizontal spring stiffness | Vertical spring stiffness |
|---|---|---|---|---|---|
| E0 = 28 N [MPa] | Kh [kN/m] | Kv [kN/m] | |||
| 1 | 4 | 112 | 0.00 | 6113.73 | - |
| 2 | 2 | 46.62 | 0.00 | 2544.84 | - |
| 3 | 1 | 23.31 | 0.00 | 1272.42 | - |
| 4 | 1 | 15.54 | 0.00 | 848.28 | 6424.86 |
| 5 | 1 | 15.54 | 0.07 | 848.28 | 110507.60 |
| 6 | 4 | 98 | 0.14 | 5349.52 | 179896.09 |
| 7 | 7 | 196 | 0.21 | 10699.03 | 229459.30 |
| 8 | 8 | 224 | 0.28 | 12227.47 | 266631.70 |
| 9 | 9 | 252 | 0.35 | 13755.90 | 295543.58 |
| 10 | 10 | 280 | 0.41 | 15284.33 | 318673.07 |
| 11 | 10 | 280 | 0.48 | 15284.33 | 337597.21 |
| 12 | 11 | 308 | 0.55 | 16812.77 | 353367.32 |
| 13 | 11 | 308 | 0.62 | 16812.77 | 366711.26 |
| 14 | 12 | 336 | 0.69 | 18341.20 | 378148.92 |
| 15 | 13 | 364 | 0.76 | 19869.63 | 388061.56 |
| 16 | 13 | 364 | 0.82 | 19869.63 | 396735.13 |
| 17 | 14 | 392 | 0.89 | 21398.07 | 404388.27 |
| 18 | 18 | 504 | 0.96 | 27511.80 | 411191.06 |
| 19 | 22 | 616 | 1.03 | 33625.53 | 417277.77 |
| 20 | 22 | 616 | 1.10 | 33625.53 | 422755.81 |
| 21 | 22 | 616 | 1.17 | 33625.53 | 427712.13 |
| 22 | 19 | 532 | 1.23 | 29040.23 | 432217.88 |
| 23 | 18 | 504 | 1.30 | 27511.80 | 436331.82 |
| 24 | 18 | 504 | 1.37 | 27511.80 | 440102.93 |
| 25 | 19 | 532 | 1.44 | 29040.23 | 443572.36 |
Table 5:
Fundamental periods and cumulative modal mass ratio (CMMR) of the building models in different conditions
| Dynamic characteristics | Fixed base | Fixed base + SSI | Base isolated | Base isolated + SSI | |
|---|---|---|---|---|---|
| Period | Mode 1 | 1.801 | 1.932 | 3.857 | 3.958 |
| Mode 2 | 1.778 | 1.892 | 3.851 | 3.951 | |
| Mode 3 | 1.660 | 1.764 | 3.603 | 3.732 | |
| Participated mass ratio (X-dir) | Mode 1 | 0.06% | 0.10% | 7.81% | 7.41% |
| Mode 2 | 79.86% | 66.90% | 98.98% | 77.16% | |
| Mode 3 | 79.91% | 66.99% | 99.16% | 77.35% | |
| Participated mass ratio (Y-dir) | Mode 1 | 76.67% | 65.63% | 89.27% | 67.56% |
| Mode 2 | 76.75% | 65.70% | 97.25% | 75.16% | |
| Mode 3 | 79.13% | 66.78% | 99.09% | 77.30% | |
Table 6:
Selected ground motions for earthquake BSE-1E
| Earthquake mechanism | Model direction | Earthquake event | Magnitude | Distance Rrup | Vs30 | PGA | Duration |
|---|---|---|---|---|---|---|---|
| [M] | [km] | [m/s] | [g] | [s] | |||
| Shallow Crustal | X | Loma Prieta, California 1989 | 6.93 | 43.23 | 133.11 | 0.22 | 35.96 |
| Y | 0.27 | ||||||
| X | Loma Prieta, California 1989 | 6.93 | 45.58 | 126.40 | 0.11 | 30.09 | |
| Y | 0.12 | ||||||
| X | Chuetsu-Oki, Japan 2007 | 6.8 | 48.66 | 149.97 | 0.06 | 74.50 | |
| Y | 0.05 | ||||||
| X | Iwate, Japan 2008 | 6.9 | 48.36 | 158.16 | 0.11 | 40.50 | |
| Y | 0.11 | ||||||
| X | Iwate, Japan 2008 | 6.9 | 45.55 | 166.750 | 0.133 | 47.22 | |
| Y | 0.130 | ||||||
| Benioff | X | Miyagi, Japan 2011 | 7.15 | 188.46 | 135.50 | 0.04 | 82.19 |
| Y | 0.04 | ||||||
| Megathrust | X | Tohoku, Japan 2011 | 9.12 | 202.99 | 152.90 | 0.06 | 180.00 |
| Y | 0.07 |
Table 7:
Selected ground motions for earthquake BSE-2E
| Earthquake mechanism | Model direction | Earthquake event | Magnitude | Distance Rrup | Vs30 | PGA | Duration |
|---|---|---|---|---|---|---|---|
| (M) | (km) | (m/s) | (g) | (s) | |||
| Shallow Crustal | X | Darfield, New Zealand 1989 | 7 | 19.48 | 141.00 | 0.24 | 30.50 |
| Y | 0.26 | ||||||
| X | El Mayor-Cucapah, Mexico 1989 | 7.2 | 41.29 | 162.94 | 0.15 | 68.90 | |
| Y | 0.18 | ||||||
| X | Loma Prieta, California 1989 | 6.93 | 43.23 | 133.11 | 0.22 | 35.96 | |
| Y | 0.27 | ||||||
| X | Loma Prieta, California 1989 | 6.93 | 45.58 | 126.40 | 0.11 | 30.09 | |
| Y | 0.12 | ||||||
| X | Iwate, Japan 2008 | 6.9 | 45.55 | 166.75 | 0.13 | 47.22 | |
| Y | 0.13 | ||||||
| Benioff | X | Chuetsu, Japan 2004 | 7.41 | 191.07 | 160.40 | 0.03 | 76.68 |
| Y | 0.02 | ||||||
| Megathrust | X | Tohoku, Japan 2011 | 9.12 | 202.99 | 152.90 | 0.06 | 180.00 |
| Y | 0.07 |
Figure 12:
Spectral response of ground motions Loma Prieta 1989 before and after matching the targeted-site spectral response of earthquake with 250 and 1000 years of return period
Figure 13:
Spectral response of ground motions Tohoku 2011 before and after matching to the targeted-site spectral response of earthquake with 250 and 1000 years of return period
Figure 14:
Comparative charts of the peak base shear in X and Y directions under earthquakes BSE-1E
Figure 15:
Comparative charts of the peak base shear in X and Y directions under earthquakes BSE-2E
Table 8:
Peak isolator displacements observed in NLTH analysis
| Parameter | Earthquake event | Base isolated | Base isolated + SSI |
|---|---|---|---|
| Isolator horizontal displacement (mm) 250 yr | Loma Prieta AR | 150.481 | 154.52 |
| Loma Prieta FM | 124.685 | 130.752 | |
| Chuetsu-Oki | 112.451 | 136.797 | |
| Iwate AKT | 70.355 | 77.644 | |
| Iwate MYG | 109.309 | 157.749 | |
| Miyagi | 133.495 | 142.794 | |
| Tohoku | 132.831 | 110.761 | |
| Average | 119.09 | 130.15 (+9.28%) | |
| Isolator horizontal displacement (mm) 1000 yr | Darfield | 279.173 | 297.74 |
| Cucapah | 277.722 | 210.176 | |
| Loma Prieta AR | 265.88 | 270.982 | |
| Loma Prieta FM | 233.222 | 165.959 | |
| Iwate MYG | 167.229 | 217.09 | |
| Chuetsu | 156.097 | 174.313 | |
| Tohoku | 112.558 | 258.589 | |
| Average | 213.13 | 227.84 (+6.90%) |
Figure 16:
Maximum interstory drift in X and Y directions under earthquake BSE-1E
Figure 17:
Maximum interstory drift in X and Y directions under earthquake BSE-2E
Figure 18:
Comparative charts of peak acceleration response at the roof level in X and Y direction under earthquakes BSE-1E
Figure 19:
Comparative charts of peak acceleration response at the roof level in X and Y direction under earthquakes BSE-2E