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 Taiwan’s Hi-Tech Industry in Taiwan’s Hi-Tech Industry

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

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

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

Configuration of Standard Fab clean room

Configuration of Double Fab cleanroom 2 cleanroom 1

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!

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)

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

Major Design Controversies (con’d) 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!

FEM Model of the Target Double Fab

Input Ground Motion Ground acceleration measured in Chi-Chi Earthquake (TCU017 station, inside HSBIP)

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

Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 1 Floor displacement and story drift ratio (PGA=0.33g)

Phase I- Performance assessment under PGA=0.33g (Grade 6 ) UBC97IBC2000 Table 2 Acceleration at cleanroom floors (PGA=0.33g)

Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 3 Maximum internal forces and stress check of column C6 (PGA=0.33g)

Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 4 Floor displacement and story drift ratio (PGA=0.50g)

Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 5 Floor acceleration (PGA=0.50g) UBC97IBC2000

Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 6 Maximum internal forces and stress check of column C6 (PGA=0.50g)

Seismic Retrofit Analysis Metallic Yielding Damper Temperature-independentTemperature-independent Maintenance-freeMaintenance-free Cost-effectiveCost-effective DurableDurable

Seismic Retrofit Analysis 90 Units of Metallic Yielding Damper to be Implemented

Seismic Retrofit Analysis Figure 9(a) Comparison of displacement responses (3F & 5F)-PGA=0.33g

Seismic Retrofit Analysis Figure 9(b) Comparison of acceleration responses (3F & 5F)-PGA=0.33g

Seismic Retrofit Analysis Figure 10(b) Comparison of displacement responses (3F & 5F)-PGA=0.50g

Seismic Retrofit Analysis Figure 10(b) Comparison of acceleration responses (3F & 5F)-PGA=0.50g

Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 1 Floor displacement and story drift ratio (PGA=0.33g)

Phase I- Performance assessment under PGA=0.33g (Grade 6 ) UBC97IBC2000 Table 2 Acceleration at cleanroom floors (PGA=0.33g)

Phase I- Performance assessment under PGA=0.33g (Grade 6 ) Table 3 Maximum internal forces and stress check of column C6 (PGA=0.33g)

Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 4 Floor displacement and story drift ratio (PGA=0.50g)

Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 5 Floor acceleration (PGA=0.50g) UBC97IBC2000

Phase II- Performance assessment under PGA=0.50g (Grade 7 ) Table 6 Maximum internal forces and stress check of column C6 (PGA=0.50g)

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.

Concluding Remarks (Con’d) 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.

Concluding Remarks (Con’d) 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.