Avoid Damage and Avoid Collapse

 

EPS Triple Pendulum isolators are implemented to comply with the Continued Functionality Standard (CFS), which limits earthquake damage to less than 2% of a building’s replacement cost, which retains post-earthquake functionality.  

The effectiveness of EPS pendulum isolators to avoid damage has been proven for over 3 decades by real earthquakes having magnitudes of up to 8.8.  The Elazig Hospital, Acapulco Emergency Response Center, Texas Instrument’s Philippines Medical Instruments Factory, 4 Ecuador bridges, and 2 Chile Liquid Natural Gas Tanks implemented Triple Pendulum isolators engineered by EPS according to the continued functionality criteria which formed the basis of the Continued Functionality Standard.  These 9 essential structures experienced earthquakes shaking with strengths ranging from 1 to 3 times the building code’s design earthquake, with all having damage of less than 2% of replacement costs, and all retaining 100% post-earthquake functionality.  These same earthquakes caused hundreds of structures to collapse, and over 100,000 buildings to suffer damage exceeding 30% of replacement costs.  http://bit.ly/2KIPx9y  http://bit.ly/2MPZjJO  This earthquake data confirms that EPS Triple Pendulum isolators compliant with the CFS reliably limit damage to 2% of building replacement costs.

Elazığ Fethi Sekin City Hospital

During Turkey’s 2020 M 6.7 Elazig earthquake, the Elazığ Fethi Sekin City Hospital retained 100% functionality, whereas 87 other multi-story buildings collapsed, and thousands others lost functionality, with 1287 later demolished.

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Christchurch Women's Hospital was constructed with lead rubber isolators. the use of isolators resulted in a lower lateral seismic strength capacity, as specified by the structure design code.

Fletcher Construction was paid $30 million to repair the structural and architectural damage from magnitude 6 earthquakes. Repair costs were 20% of building replacement costs.

The researchers at the University of Christchurch recorded the isolator displacements and building accelerations that occurred during two M6 earthquakes. Canterbury University reported the lead-rubber isolators "did not displace", and the hospital responded "essentially as if it was fixed base" [Kuang].

With EPS Triple Pendulum Isolators a building avoids damage from earthquakes that are 10 times stronger than the earthquakes that damage new buildings designed only for code compliance.  Construction costs for Continued Functionality are typically 5% to 10% more than construction costs for quality built buildings constructed only to reduce the risk of collapse to 10%.  To date, 100 million square feet of hospitals and important structures have been constructed with pendulum isolators designed by EPS to retain post-earthquake functionality.
CFS compliant isolators limit damage to 2% by reducing the in-structure accelerations and deformations to post-earthquake functionality levels, in compliance with the Continued Functionality Standard.  Since the 1989 California earthquake, all facilities with EPS pendulum isolators have retained 100% post-earthquake functionality. 
The seismic performance objective of the building codes, with or without isolators, is to reduce the risk of collapse, such that most occupants can walk out of the buildings alive.  The standard practice of Structural Engineers has been to design new buildings for minimum compliance with the building codes, which intend that less than 10% of new buildings will collapse.  Each year, when the code’s maximum considered earthquake shaking occurs, the damage observed in new buildings is typically equal to a building’s replacement cost.  Each year earthquakes cause hundreds of code designed buildings to collapse, with thousands more that remain standing but are later demolished, and millions more that suffer earthquake damage exceeding 30% of the building’s replacement costs.  Earthquakes have caused millions of people to lose 100% of their investments in their buildings.  EPS Triple Pendulum isolators economically protect those investments, making it irrational to construct buildings to be intentionally damage by earthquakes, as specified by the building codes.  

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Three days after the magnitude 6.3 earthquake, from the air, the Christchurch City Center appears unaffected,

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Three years after the magnitude 6.3 earthquake, 70% of buildings in the Christchurch City Center had been demolished because the earthquake damage was not economically repairable. 

Seven years after the earthquake, only 60% of the buildings had be replaced.

Median loss of property use - 6 years.

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New Code Compliant Building constructed in 2008, damaged during the 2010 Chile Earthquake, Demolished 2012

Warning: not all seismic isolators minimize damage.

European EN15129 isolators are dangerous collapse hazards.

Trans-European Motorway, Bolu, Turkey 1999
Trans-European Motorway, Bolu, Turkey 1999

With European seismic isolators nearly collapsed and suffered 100% economic loss from Turkey’s 1999 M7.4 Earthquake.

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Trans-European Motorway, Turkey 1999
Trans-European Motorway, Turkey 1999

Bridge girders are not supported on the piers.

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Trans-European Motorway Retrofit
Trans-European Motorway Retrofit

Friction Pendulum Isolators from EPS were used to retrofit the damaged viaduct. The EPS pendulum isolators had 4 times the displacement capacity of the European isolation system, but the purchase price was less. EPS pendulum isolators were also installed in three additional Trans-European Motorway viaduct sections.

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Trans-European Motorway, Bolu, Turkey 1999
Trans-European Motorway, Bolu, Turkey 1999

With European seismic isolators nearly collapsed and suffered 100% economic loss from Turkey’s 1999 M7.4 Earthquake.

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Continued Functionality Isolators

 

Continued Functionality Standard

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 Cover of ASCE 7-16

American Society of

Civil Engineers

 

ASCE 7-16

Chapter 1

Functionality Requirements

1.3.3 Functionality. Structural systems and members and connections thereof assigned to Risk Category IV shall be designed with reasonable probability to have adequate structural strength and stiffness to limit deflections, lateral drift, or other deformations such that their behavior would not prevent function of the facility immediately following any of the design level environmental hazard events specified in this Standard.

REDi: Resilience-based Earthquake Design Initiative
REDi Resiliency Objectives

Qualified Manufacturers and Code Compliant Seismic Isolation

 

Building codes allow structural members to be damaged during earthquakes, and some collapses of newly built structures are expected to occur. Expert seismic isolation engineering, quality manufactured bearings, and bearing performance criteria more stringent than code compliance, can effectively avoid damage to all structure members, which is the ultimate goal of seismic isolation technology.

Seismically isolated structures that are well designed and built minimize economic losses caused by earthquake shaking, and also reduce construction costs. Unqualified bearing manufacturers, or seismic isolation bearings that satisfy only the minimum building code requirements, can cause major structural damage and collapse. Since 1987, important applications of seismic isolation have selected manufacturers that have qualified their bearings through rigorous testing and successful in-service performance. Achieving reliable damage protection requires expert seismic isolation engineering, quality manufactured bearings, and specifying seismic performance more stringent than minimum code compliance.

Bearings made by unqualified fabricators without proven industry standards are extremely dangerous. In 1999, the newly constructed Trans-European Motorway in Turkey that had been seismically isolated came close to complete collapse due to poor seismic isolation engineering and products. Over 1000 seismic isolation bearings and dampers failed, and structure repair costs were over US $100 Million. Public safety requires that construction plans specify 
qualified bearing manufacturers that have proven the adequacy of their products, materials and manufacturing standards.