Seismic Isolation for Small - Buffalomceer.buffalo.edu/education/reu/04Presentations/009Carrillo.pdf · Seismic Isolation for Small ... For design loads and base isolation design.!Algerian

Seismic Isolation for Small Seismic Isolation for Small Reinforced Concrete StructuresReinforced Concrete Structures

A Preliminary Investigation on Material CostA Preliminary Investigation on Material CostA Preliminary Investigation on Material Cost

Investigated and Presented by:Investigated and Presented by:

Abiel Carrillo

Advisor:

Dr. George C. LeeSamuel P. Capen Professor

Advisor:

Dr. George C. LeeSamuel P. Capen Professor

Abiel Carrillo

Multidisciplinary Center for Earthquake Engineering Research

ObjectiveObjective

The objective of this The objective of this investigation is to show investigation is to show the effectiveness of a the effectiveness of a specific rubber bearing specific rubber bearing isolation design of a isolation design of a symmetrical, lowsymmetrical, low--rise rise reinforced concrete reinforced concrete structurestructure in the region of in the region of Algeria, AfricaAlgeria, Africa


Motivation for this investigationMotivation for this investigation

One evening in May, 2003, Algeria was struck by its worst earthquake in 23 years. More than 2,000 people were killed and over 9,000 injured. Many homes were destroyed in the initial quake and thousands more were damaged and made uninhabitable.

One evening in May, 2003, Algeria was struck by its worst earthqOne evening in May, 2003, Algeria was struck by its worst earthquake uake in 23 years. More than 2,000 people were killed and over 9,000 in 23 years. More than 2,000 people were killed and over 9,000 injured. Many homes were destroyed in the initial quake and injured. Many homes were destroyed in the initial quake and thousands more were damaged and made uninhabitable.thousands more were damaged and made uninhabitable.


A1

Motivation for this investigationMotivation for this investigation

To explore a system To explore a system that could protect that could protect similar structures, similar structures, preventing disasters preventing disasters like this.like this.


Slide 5

A1 Some structures experienced non structural damage, others buckled, other completely destroyedAbiel Carrillo, 7/25/2004

ObjectiveObjective

As will be explained later, base isolation in general can be one of the safest or most cost effective ways of designing a structure in a highly seismic zone. The results of this investigation, focus on a specific example.

As will be explained later, As will be explained later, base isolation in general base isolation in general can be one of the safest can be one of the safest or most cost effective or most cost effective ways of designing a ways of designing a structure in a highly structure in a highly seismic zone. The results seismic zone. The results of this investigation, focus of this investigation, focus on a on a specific examplespecific example..


OverviewOverview

oo Method and Codes Method and Codes oo Design Loads Design Loads oo Parameters and AssumptionsParameters and Assumptionsoo Base IsolationBase Isolationoo Summary of ResultsSummary of Resultsoo ConclusionsConclusionsoo ReferencesReferences


Method and Codes Used

Two possible frames were designed, A and B, and the total required material was then compared:

A. Moment resisting frame B. Base isolated frame

Isolator


Method and CodesMethod and Codes

The design steps for base isolation ultimately shift the frame’s period.

Acceleration is significantly reduced, which means that smaller lateral forces are developed


Method and Codes

! American Concrete Institute (1999)For floor system, girder, column and foundation design.

! Uniform Building Code (1997)For design loads and base isolation design.

! Algerian Seismic CodeFor Equivalent static earthquake loading applied to moment frame A


Design LoadsDesign Loads

!Earthquake loads were determined from a static lateral equivalent calculation based on Algerian Seismic Codes.

!!Earthquake loads were determined from a Earthquake loads were determined from a static lateral equivalent calculation based static lateral equivalent calculation based on Algerian Seismic Codes. on Algerian Seismic Codes.

72 kip72 kip

40 kip40 kip


Parameters and Assumptions

Steel Steel ffyy 60 60 ksiksi

Conc. Conc. ff’’cc 3 3 ksiksi

Allowable

Details were as follows:Details were as follows:

90 ft

Allowable Soil stressSoil stress 4 4 ksiksi

90 ft

27 ft

OccupancyOccupancy OfficesOffices

Seismic Seismic ZoneZone 33

Dead LoadDead Load 12 12 psfpsf

Roof LiveRoof Live 20 20 psfpsf

Floor LiveFloor Live 50 50 psfpsf


Base Isolation DesignBase Isolation Design

There are various isolation methods and devices available and are being developed, and the Code does not “prefer” a type, nevertheless it requires that the system have the following three properties:

1. Be stable for the required displacement

2. Provide increasing resistance with increasing displacement

3. Does not degrade under cyclic loading


A2


Selected Isolation: High Damping Rubber Bearing

Thin steel shims (circular plates) increase bearing strength

Thin steel shims (circular plates) increase bearing strength

Rubber cylinder

Steel plate


Slide 14

A2 There are many others which i encourage you to look at but in the interest of time..Abiel Carrillo, 7/25/2004

A3


Steps for a Code based design:Steps for a Code based design:

1. Determine and establish parameter-dependent factors.

2. Select a type of bearing and estimate target values, such as stiffness, damping ratio and bearing displacement.

3. Relate required dimensions of the isolation bearing unit with target values from step 2.

4. Detail actual dimensions for isolation unit.

1. Determine and establish parameter-dependent factors.

2. Select a type of bearing and estimate target values, such as stiffness, damping ratio and bearing displacement.

3. Relate required dimensions of the isolation bearing unit with target values from step 2.

4. Detail actual dimensions for isolation unit.


Slide 15

A3 There are many steps but basically...Abiel Carrillo, 7/25/2004

Summary of ResultsSummary of Results

The resultant design called for 16 units with the following dimensions:

17 ” rubber diameter

11 “ height

12 gage shims


Summary of ResultsSummary of Results

AAA

A / B weight ratios of main structural elementsA / B weight ratios of main structural elements

Concrete ratio Steel ratio

Girders 1.71.7

1.51.5

2.32.3

4.94.9 Steel in Base Isolated frame is Steel in Base Isolated frame is not continuousnot continuous

Columns 3.23.2 A minimum amount of concrete A minimum amount of concrete required in both columnsrequired in both columns

Foundations 1.81.8 Same rebar diameter, just larger Same rebar diameter, just larger dimensionsdimensions

B


ConclusionsConclusions

! Base Isolators can be expensive, but the rubber bearings chosen are very common. The final design calls for 16 units, which doesn’t compare to having a total of 3.3 times more steel as required in the larger reinforced frame.



! Results for other structures can vary significantly

Factors that influence structural design:

- Importance of building- Soil profile- Availability and shipping- Height of structure- Labor - Site plan- Architectural requirements- Other factors

! Results for other structures can vary significantly

Factors that influence structural design:

- Importance of building- Soil profile- Availability and shipping- Height of structure- Labor - Site plan- Architectural requirements- Other factors



! Base Isolation also protects non-structural elements and equipment by reducing the entire structure’s acceleration during an earthquake, as opposed to reinforcement alone.

! Base Isolation also protects non-structural elements and equipment by reducing the entire structure’s acceleration during an earthquake, as opposed to reinforcement alone.

Frame is still standing but non-bearing walls could not withstand the strong shaking.

Frame is still standing but non-bearing walls could not withstand the strong shaking.


A5

Slide 20

A5 include equipment isolation, like in a museumAbiel Carrillo, 7/26/2004

ReferencesReferences

! Paz, Mario. International Handbook of Earthquake Engineering : Codes, Programs and Examples.October, 1994; Chapman and Hall. London, England.

! McCormack, Jack. Design of Reinforced Concrete.2001; John Wiley & sons, Inc. New York, New York.

! Kelly, James M.; Naeim, Farzad. Design of Seismic Isolated Structures: From Theory to Practice.1999; John Wiley & sons, Inc. New York, New York.


AcknowledgementsAcknowledgements

! - Multidisciplinary Center for Earthquake Engineering Research

! Dr. George C. Lee

Samuel P. Capen Professor

! Civil Engineering Dept. , Univ. at Buffalo


“One's mind, once stretched by a new idea, never regains its original dimension.”

- Oliver Wendell Holmes

Documents

Seismic Isolation for Small - Buffalomceer.buffalo.edu/education/reu/04Presentations/009Carrillo.pdf · Seismic Isolation for Small ... For design loads and base isolation design.!Algerian