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Y.P. Wang 1, W.H. Liao 2 and C.L. Lee 2 1 Professor of Civil Engineering 2 Research Assistant Professor of NHMRC National Chiao-Tung University Y.P. Wang 1, W.H. Liao 2 and C.L. Lee 2 1 Professor of Civil Engineering 2 Research Assistant Professor of NHMRC National Chiao-Tung University Seismic Risks of Typical Double Fabs in Taiwans Hi-Tech Industry in Taiwans Hi-Tech Industry Slide 2 Motivation Experiencing Unexpectedly High Seismic Loss in Moderate Earthquakes Anticipating Big Shocks to Occur Nearby Hsinchu and Tainan Science- based Industrial Parks Increasingly Growing Expense in Industrial Insurance or No Insurance Slide 3 Sources of Seismic Loss Interruption due to Power Breakdown Damage/Dislocation of Process Tools Damage of Raised Floor Pounding of Fab with Support Building Subsequent Operation Interruption Slide 4 Objectives Seismic Performance Assessment of An Existing Double Fab Structure A Case Study A Case Study Seismic Retrofit Analysis of the Target Double Fab Structure Slide 5 Configuration of Standard Fab clean room Slide 6 Configuration of Double Fab cleanroom 2 cleanroom 1 Slide 7 Structural Plans Structural plans at 1~2 F (Sub-fabs) Structural plans at 3F and 5F (Clean Rooms) Lateral Stiffness Reinforcement Only in the Peripheral Frame! Slide 8 Potential Problems of Double Fabs Soft-story and Weak-story in Cleanroom Levels due to Excessive Storydrift and P- Effects Excessive Amplification of Floor Acceleration at the Upper Cleanroom (Suffering Greater Loss Than Lower Cleanroom) Slide 9 Major Design Controversies Completely following the Ductility Design Structurally Non-uniform due to Soft-storiesStructurally Non-uniform due to Soft-stories No Plastic Hinges will be Formed in the Waffle Slab for its High RigidityNo Plastic Hinges will be Formed in the Waffle Slab for its High Rigidity Desired Strong-column-weak-beam Condition Assumed in Design is not TrueDesired Strong-column-weak-beam Condition Assumed in Design is not True Structurally Non-ductile, Reduction of Base Shear by Code Formula is not Accountable Structurally Non-ductile, Reduction of Base Shear by Code Formula is not Accountable Slide 10 Major Design Controversies (cond) Perform Static Analysis Only Fail to Verify the Ultimate Strength of the Story Shears Even for the Cleanroom Levels No Peer Review of the Structural Design Has Been Conducted! Slide 11 FEM Model of the Target Double Fab Slide 12 Input Ground Motion Ground acceleration measured in Chi-Chi Earthquake (TCU017 station, inside HSBIP) Slide 13 Seismic Performance Indecies Storydrifts between All Floor Levels Accelerations at the Cleanroom Floor Levels Stress State under Critical Loading Condition by ASD Stability interaction equation Slide 14 Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 1 Floor displacement and story drift ratio (PGA=0.33g) Slide 15 Phase I- Performance assessment under PGA=0.33g (Grade 6 ) UBC97IBC2000 Table 2 Acceleration at cleanroom floors (PGA=0.33g) Slide 16 Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 3 Maximum internal forces and stress check of column C6 (PGA=0.33g) Slide 17 Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 4 Floor displacement and story drift ratio (PGA=0.50g) Slide 18 Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 5 Floor acceleration (PGA=0.50g) UBC97IBC2000 Slide 19 Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 6 Maximum internal forces and stress check of column C6 (PGA=0.50g) Slide 20 Seismic Retrofit Analysis Metallic Yielding Damper Temperature-independentTemperature-independent Maintenance-freeMaintenance-free Cost-effectiveCost-effective DurableDurable Slide 21 Seismic Retrofit Analysis 90 Units of Metallic Yielding Damper to be Implemented Slide 22 Seismic Retrofit Analysis Figure 9(a) Comparison of displacement responses (3F & 5F)-PGA=0.33g Slide 23 Seismic Retrofit Analysis Figure 9(b) Comparison of acceleration responses (3F & 5F)-PGA=0.33g Slide 24 Seismic Retrofit Analysis Figure 10(b) Comparison of displacement responses (3F & 5F)-PGA=0.50g Slide 25 Seismic Retrofit Analysis Figure 10(b) Comparison of acceleration responses (3F & 5F)-PGA=0.50g Slide 26 Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 1 Floor displacement and story drift ratio (PGA=0.33g) Slide 27 Phase I- Performance assessment under PGA=0.33g (Grade 6 ) UBC97IBC2000 Table 2 Acceleration at cleanroom floors (PGA=0.33g) Slide 28 Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 3 Maximum internal forces and stress check of column C6 (PGA=0.33g) Slide 29 Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 4 Floor displacement and story drift ratio (PGA=0.50g) Slide 30 Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 5 Floor acceleration (PGA=0.50g) UBC97IBC2000 Slide 31 Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 6 Maximum internal forces and stress check of column C6 (PGA=0.50g) Slide 32 Concluding Remarks Excessive storydrifts of the double fab are found between the clean room levels under the design earthquake intensity. The concern of the double fab structure to contain soft and weak stories has been confirmed. Slide 33 Concluding Remarks (Cond) The proposed seismic retrofit design using metallic yielding dampers proves to be effective and sufficient under the design earthquake intensity. More dampers are demanded for further improvement of the seismic performance at the earthquake intensity level of PGA=0.5g. Slide 34 Concluding Remarks (Cond) The code specified design values for seismic anchorage of facility are somewhat conservative as compared with the time history responses under the specific earthquake episode with PGA=0.33g. Yet, this does not warrant damage-free and function integrity of the tools from a performance-based design point of view.