Structural Selection and Economic Analysis of Isolated and...

Structural Selection and Economic Analysis of

Isolated and Non-isolated Shopping Mall Located

at Seismic Intensity 9

Speaker: Chi Miao

Supervisor: Ying Zhou

College of Civil Engineering

Tongji University

2013.08

Outline

1. Introduction

2.1 Comparison of Mechanic Behavior

3. Conclusions

Outline

2. What I did

2.2 Economic Analysis

Introduction

Because of the isolation layer,

the natural periods of isolated structures will

become longer and the influence of

earthquake on structures will thus be

effectively reduced.

1.1 Introduction: Theory of Isolation

Isolation

1.1 Introduction: Theory of Isolation

Seismic Response Spectrum in Chinese Specification

There are more than 2000 isolated buildings all over

the world, about half of which located in Japan.

1. 2 Introduction: Practical Projects

Isolation layer

The first isolated hospital in the world was constructed in America：the University of Southern California Teaching Hospital.

1.2 Introduction: Practical Projects

Strong earthquake with Magnitude 6.7 broke out in California in 1994

USC Teaching Hospital Olive View Hospital

Story\ Acceleration USC Teaching Hospital Olive View Hospital

Base 490 gal 820 gal

Top 210 gal 2310 gal42.8% 281.7%

1. Chinese specifications not only have the role of guiding, but also are laws to

which the structural design must conform. And Chinese specifications were written

based on Chinese conditions.

Whether the isolation technology is also that effective in China?

2. Most isolated buildings were constructed in the developed countries.

Since China is a developing country, whether the isolation technology is economical?

Questions

What I did

2.1 What I did: Comparison of Mechanic Behavior

2.1.1 Concept of Seismic Intensity 9 in Chinese Specification

Based on the exceeding probability of intensity in 50 years, there

are mainly 5 categories of regions in China, as blow:

(1)Regions where earthquake influence may not be considered.

(2)Seismic Intensity 6 Basic Design Acceleration: 50gal




Peak ground acceleration of elastic analysis: 140gal

Peak ground acceleration of elastic-plastic analysis: 620gal

2.1 What I did: Comparison of Mechanic Behavior Chinese Zoning Map of Peak Ground Acceleration

PGA

(unit: g)


2.1.2 Three Analytical Models (Etabs) and Lead Rubber Bearings

(1) 3-D Analytical Model of the Frame-Shear Wall Structure

Plan layout of the 1st floor of the

frame-shear wall structure

3-D analytical model of the frame-

shear wall structure


(2) 3-D Analytical Model of the Small-bay Frame Structure


small-bay frame structure

3-D analytical model of the small-

bay frame structure


(3) 3-D Analytical Model of the Isolated Frame Structure


isolated frame structure

3-D analytical model of the

isolated frame structure

LRB700


(4) Lead Rubber Bearings in the Isolated Frame Structure

Factors of rubber isolation bearing

Lead

Rubber Layers

Installation of LRB

Type

DiameterDiameter

of lead

Vertical

stiffnessMechanic behavior of shear deformation of 100%

(mm) (mm) (kN/mm)

Yield

strength

Initial

stiffness

Stiffness

after yielded

Equivalent

Stiffness

Damping

ratio

(kN) (kN/mm) (kN/mm) (kN/mm) %

LRB700 700 110 3509 76 14.37 1.105 1.661 20.4


2.1.2 Time History Analysis of Three Models

(1) Natural periods of isolated and non-isolated structures (s)

Frame-shear wall

structure

Small-bay frame

structure

Isolated

frame structure

The 1st period

The 2nd Period

The 3rd Period

0.230

0.168

0.116

0.421

0.363

0.320

2.216

2.120

1.782

It can be seen that the seismic action of non-isolated structures

in high seismic intensity zones may possibly reach their

maximum code limits which could be greatly reduced by

applying isolation technique.

Around 0.4


Seismic Response Spectrum in Chinese Specification

0.4 2.0

0.230 0.421 2.216

Decrease


(2) Natural and Artificial Records for Analysis

Natural earthquake records for time history analysis under minor earthquakes

Name of the natural records Base station Year

NGA_800LOMAP.SJW_FP SALINAS JOHN & WORK 1989

NGA_838LANDERS.BRS_FN BARSTOW 1992

NGA_1489CHICHI.TCU049_FN TCU049 1999

NGA_2752CHICHI04.CHY101_FP CHY101 1999

NGA_3276CHICHI06.CHY037_FP CHY037 1999

Natural earthquake records for time history analysis under major earthquakes

Name of the natural records Base station Year

NGA_800LOMAP.SJW_FP SALINAS JOHN & WORK 1989

NGA_1489CHICHI.TCU049_FN TCU049 1999

NGA_176IMPVALL.H-E13_FP

NGA_1489CHICHI.TCU049_FP

NGA_1493CHICHI.TCU053_FN

EL CENTRO ARRAY #13

TCU049

TCU053

1979

1999

1999


Natural earthquake records for time history analysis under

minor earthquakes


Natural earthquake records for time history analysis under

major earthquakes


(3) Elastic inter-story drift of time history analysis

X StoryFrame-shear

wall structure

Small-bay

frame

structure

Isolated

frame

structure

Y StoryFrame-shear

wall structure

Small-bay

frame

structure

Isolated

frame

structure

4 1/941 1/831 1/1975 4 1/1107 1/832 1/1759

3 1/1911 1/1025 1/1408 3 1/1319 1/755 1/1282

2 1/5956 1/963 1/1100 2 1/2147 1/625 1/1037

1 1/13107 1/1022 1/1060 1 1/4895 1/857 1/950

As is shown, the maximum inter-story drift of isolated

structure (1/950) is less than that of frame-shear wall structure

and small-bay frame structure, which is 1/941 and 1/625

separately.


(4) Inter-story shear of time history analysis (N)

As is shown, the inter-story shear forces of isolated structure are far

less than those of non-isolated structure. In the first story where the

maximum inter-story force occurs, the inter-story shear forces of

isolated structure in X and Y direction are merely 28.2%, 20.3% and

21.1%, 19.9% of frame-shear wall structure and small-bay frame

structure separately.

X Story

Frame-shear

wall

structure

Small-bay

frame

structure

Isolated

frame

structure

Y Story

Frame-shear

wall

structure

Small-bay

frame

structure

Isolated

frame

structure

4 7.16E+05 7.77E+05 1.39E+05 4 6.27E+05 6.00E+05 1.36E+05

3 2.04E+06 2.17E+06 4.58E+05 3 2.75E+06 2.40E+06 4.31E+05

2 3.24E+06 3.94E+06 9.14E+05 2 4.15E+06 4.22E+06 8.51E+05

1 4.08E+06 5.44E+06 1.15E+06 1 5.58E+06 5.68E+06 1.13E+06

20.3%

28.2%

19.9%

21.1%


(5) Floor acceleration (m/s2)

X Story

Frame-shear

wall

structure

Small-bay

frame

structure

Isolated

frame

structure

Y Story

Frame-shear

wall

structure

Small-bay

frame

structure

Isolated

frame

structure

4 10.58 7.30 1.49 4 7.05 6.02 1.51

3 3.79 3.67 1.08 3 4.18 4.03 1.09

2 2.07 2.67 0.80 2 2.89 2.87 0.82

1 1.72 1.91 0.72 1 1.95 1.70 0.72

As is shown, the floor accelerations of isolated structure under

minor earthquake are far less than those of non-isolated structures.

In the top story where the maximum acceleration occurs, the floor

accelerations of isolated structure in X and Y direction are merely

14.1%, 20.9% and 20.4%, 24.5% of frame-shear wall structure and

small-bay frame structure, separately.

20.9%14.1%

24.5%20.4%


(6) Dynamic magnification factors of floors

As is illustrated, the dynamic magnification factor of

isolated structure is far lower than that of non-isolated

structure which indicates that the isolation bearing reduces

earthquake energy input efficiently.

X direction Y direction


(7) Elastic-plastic inter-story drift of the isolated structure

As is shown, the maximum elastic-plastic inter-story drift of isolated

frame structure is 1/343 under rare earthquake which is merely 14.58%

of the 1/50 code limit specified by term 5.5.5 of seismic code. This

indicates that the isolation bearings reduce the upper structure

deformation significantly thus ensures the structure safety.

Direction\Story 1st 2nd 3rd 4th

X 1/382 1/461 1/615 1/947

Y 1/343 1/404 1/535 1/806

2.2 What I did: Economical Analysis


2.2.1 Reinforced concrete consumption of the upper structures (t)

The material consumption of isolated upper structure is equivalent to 79.7% of

the frame-shear wall structure and 74.9% of the small-bay frame structure.

2.2.2 Average longitudinal rebar ratio of columns (%)

StoryFrame-shear

wall structure

Small-bay

frame

structure

Isolated

frame

structure

4 1.86 1.35 1.15

3 1.06 1.12 1.1

2 1.13 1.43 1.22

1 1.3 3.79 2.34

Frame-shear

wall structure

Small-bay

frame

structure

Isolated frame

structure

1.20E+03 1.28E+03 9.59E+02

In addition to cross section dimension reduction, the reduction in seismic

effect can enormously reduce the reinforcement ratio. The reinforcement ratio

of isolated structure is merely 61.74% of the small-bay frame structure.


2.2.3 Information from other practical projects

The direct building costs was reduced by 6%.

Museum in Shantou


The paper Economy analysis of seismic isolated structure [4]

provides 4 examples of actual construction cost of projects in

Gansu Province.

In combination with the analysis and information above, a

conclusion could be drawn:

For multi-story reinforced concrete buildings in high seismic

intensity zones, the direct construction cost of isolated

structures could be 1% to 5% lower than the non-isolated

scheme under the condition that the isolated structure is well-

designed.

The mechanic

behaviors of

isolated

structure are

much better

than that of the

non-isolated

structure.

When isolated

structures are

designed

reasonably,

construction cost

could be reduced.

At least, there is

no more economic

obstacles.

The isolation

technology has a

bright future in

the places with

high seismic

intensity in China.

3. Conclusion

[1] Zhou Fulin. Structure seismic control[M].Beijing: Seismological

Press,1996.

[2] Architecture Institute of Japan. Designing methods of base-isolated

buildings[M]. Beijing: Seismological Press,20066.

[3] Chen Huaming, Liu Qingwei, Ge Wei. Base isolation design of a brick

masonry residence building supported with frame-shear wall[J]. Structural

Engineers.2004,20(4):55-59.(in Chinese)

[4] Dang Yu, Du Yongfeng, Bi Changsong. Economy analysis of seismic

isolated structure[J].Earthquake Resistant Engineering and

Retrofitting,2006,28(4):37-40.(in Chinese)

[5] Wei Dan, Shi Weixing, Zhu Yan. Comparative testing research on seismic

performance of several types of isolators[J]. Structural

Engineers.2011,27(4):121-127.(in Chinese)

[6] Ministry of Construction of the People’s Republic of China. GB 50011-

2010 Code for seismic design of buildings [S]. Beijing: China Architecture

and Building Press, 2010

[7] OSAKI Yorihiko(Author), Tian Qi(Translator). SHIN JISHINDO NO

SPECTRE KAISEKI NYUMON[M].Beijing: Seismological Press,2008

Inference:

Thanks for attention !!Thanks for your attention!!

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