Presentation on theme: "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."— Presentation transcript:
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 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!
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.