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Study of Seismic Code Japan BCG, Europe EC8, Chile, America

IBC, IS India, and New Iranian Earthquake Code

Mohammad Reza Baradaran

, Abolfazl Heydarpoor

1- Department of Civil Engineering, Firoozabad Branch, Meymand Center, Islamic Azad University, Meymand, Iran.

2- Department of Civil Engineering, Zarghan Branch, Islamic Azad University, Zarghan, Iran.

Received: 28/07/2015 Accepted: 6/09/2015 Published: 30/09/2015

Abstract

The earthquake is one of the natural phenomena that are likely to happen in all countries of the world. Therefore, in order to

maintain safety, different countries have attempted to write their own seismic Regulations and under these circumstances, the

countries that have more seismicity as per the experience of the earthquake and assess the damage caused by the earthquake have

written Regulations that conform to their own region. This paper reviews the Regulations in Europe and the countries such as

Japan, Chile, America, India and also old and the new Regulations of Iran. In summation, it has been investigated the strong

points and failings of each of them. It is worth mentioning that the old version of the Iranian Earthquake Code (Standard No.

2800 – 3

rd.

Edition) & the new edition of Iranian Earthquake Code (Standard No. 2800 – 4

. Edition) have been evaluated herein,

and has been stated the applied modifications as well.

Keywords: Seismic Code, Earthquake, Iran, Japan, Chile, America, India.

1 Introduction

Japan is located in the center of several seismic areas.

There are two areas with high and moderate seismicity in

the Pacific Ocean and a moderate seismic zone in the Sea

of Japan. Japan has the regulation seismic design adopted

in 1981 and known by the name BCJ. This regulation has

two levels of seismic forces: one for the operation and the

other for safety of life. Most of the available methods in the

regulation have been recognized as valid. The validity of

the most existing methods in the regulation of BCG has

been examined during twenty years of practical experience,

as most of the structures that are designed using the

Regulations have endured several major earthquakes such

as the 1995 Kobe earthquake [1].

In recent years, the situation of the Europe seismic

design regulation EUROCODE 8 (EC8) has been modified

from the Pre- standard to the European standard mode. The

new regulation should change some of the national seismic

standards for some countries. Several approaches such as

design criteria according to the capacity or the coefficients

of the seismic force reduction, which are clearly correlated

with the expected structural plasticity introduce European

seismic design in a new and innovative form for steel

structure [2].

Corresponding author: Mohammad Reza Baradaran,

Department of Civil Engineering, Firoozabad Branch,

Meymand Center, Islamic Azad University, Meymand,

Iran. E-mail: mohamadrezabaradaran@gmail.com

Chile is considered as one of the most seismically

active regions of the world where the largest earthquake

event in the world recorded in 1960. February 27, 2010

Chilean earthquake of magnitude 8 / 8 M_W poses one of

the largest earthquakes in the universe that in spite of

considerable magnitude, have left little property damages

and casualties. As the number of casualties of the

earthquake have been reported less than 600 people. The

foregoing earthquake is considered as a testing field for the

Chilean seismic regulation after the occurrence large

earthquake of 1960. Chilean earthquake code is the last

edition was published as NCh433.0f96 in 1996 [3].

America is considered as one of the other world's

seismic zones and a substantial number of major

earthquakes occurred in this region of the world. The

America seismic regulation is called “IBC” which the last

edition was published in 2009. The regulation is compatible

with other international Regulations published by the

International regulation Council. Chapter 16 of the

regulation is under the title of the structural design which is

based seismic design and key standard ASCE 7 is also its

complementary which is used as "Minimum Design Loads

for Buildings and Other Structures" [4].

India and Iran are located in one of the three zones of

world's seismicity (Alpide belt) that the issue caused many

casualties occurred resulting from the phenomenon of

earthquakes in these countries in recent years. India seismic

design code is known as the ISI [5].

Iranian code of practice for seismic resistant design of

buildings (Standard No. 2800) was prepared for the first

time in 1367. The third edition of the Regulations was

published by the Building and Housing Research Center in

Journal web link: http://www.jett.dormaj.com

J. Environ. Treat. Tech.

ISSN: 2309-1185

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1384and also the latest version of the Regulations (Fourth

Edition) was published in 1393 [6].

2 Comparisons of the Regulations of Japan

BCG, Europe EC8, Chile, America IBC, IS

India and Iran

Comparing between the Regulations and survey the

differences among them have been always deemed

complicated discussions in earthquake engineering.

Standard No. 2800 of Iran is not as generally expressed as

the Chilean Regulations, nor that has been able to present

the parameters discussed in details such as the Regulations

of America. Of course, concerning Chilean Regulations,

lack of attention to detail cannot be taken into account as

neglect or failure of efficiency. The results obtained of the

Chilean earthquake of February 27, 2010 represent

applying the provisions of the Regulations. In that

earthquake, it was damaged less than 2.5 percent of

engineering structures and it can be said that this regulation

has been able to considerably meet the expectations of the

Chilean engineers society. Considering the America

Regulations also expressed a fairly substantial detail

specifically reflecting the results of research and

undergraduate studies show, in criteria of this leading

Regulation. A parameter study in these Regulations shows

a lot of common cases, but there are important differences

that can be named briefly the most important ones, such as

analysis method, soil classification, important factors,

behavior coefficients, period, expressing irregulars and

random twist, drift allowed, earthquake force distribution

and load combinations. In general, it has been debated that

the America Regulations specifically has been more details

and also is expected to be gradually considered similar

details in the other Regulations. Chilean Regulations have

been a bit more conservative and with respect to the sever

seismic background of Chile, can be said that taking such a

position is not unexpected.

Comparing the range of the Iranian Code (Standard

2800) with the spectrum of the world's seismic Regulations

posed such as EC8, BCJ and IS, and also after spectral

analysis and comparison of the base shear forces and

relative displacement in frames 3, 6, 9 and 12 storey, the

following results will be achieved:

- During the short period and in the field of the spectral

acceleration of Regulations almost conform to the code

BCJ and while that shear force differs from one another and

it is due to the different behavior coefficients in the

Regulations.

- Base shear force of spectrum EC8 has the ascending

mode, at the first, by the height increasing and prolongation

of the period and then the descending status so that the

base shear force of 12-storey building is 40% less than the

base shear force of 9-storey building so it seems that the

effect of whip force is not properly considered and seems

the modal analysis is required that in the high frequency

period However, in other Regulations by increasing the

number of classes and to increase the period of structure

can be seen clearly the effect of the whip force which is

tangible in the Japan Regulations.

- In mid-rise buildings that have period about 1 to 3

seconds, given that the 2800 code elastic range during this

time interval is a little more than the elastic range of the IS

& EC7 Regulations; in addition to this, by increasing the

height, the drift rises in the Iranian code and is ahead of

both Regulations EC8 and IS in the form of 12–story

building as well. It appears that due to the high behavior

coefficient (R) of the moment frame in 2800 shows the

shear force and the displacement less than usual.

- Base shear force of the spectrum EC8 is still raised by

increasing the height range BCJ, and this is due to the high

range and low coefficient behavior (R3. 33) of the

regulation so that even quantities of the shear range of 2800

are more than an average of 40% static shear mode and this

is dependent on the seismicity circumstances of Japan.

- Experimental period does not differ too much in each of

Regulations and in merely a short building, the period

considered in Japan Regulations is much lower than the rest

of Regulations. Experimental period is extracted from the

Iranian Code and this is because of the conditions assumed

in the modeling.

3 Summary of Iranian Code of Practice for

Seismic Resistant Design of Buildings

(Standard No. 2800 – 3

edition)

The goal of this Regulation is determination of the

minimum standards and regulations for the design and

construction of the building against the effects of the

earthquake, so that with respect to this is expected the

following issues:

A. Maintaining the stability of the building in the event

of a severe earthquake, be minimized casualties and

also building is able to resist against the mild and

moderate earthquakes without significant structural

damage.

B. Buildings with high importance must be able to keep

their capacity utilization in the event of mild and

moderate earthquake and also in buildings with

moderate importance be minimized the structural and

non-structural damages.

C. Buildings with very high importance keep their ability

to operate during the severe earthquake without major

structural damage without interruption.

D. This regulation is used for the design and construction

of buildings of reinforced concrete, steel, wood and

masonry materials. It should be noted that the specific

structures such as dams, bridges and jetties and marine

structures and nuclear power plants and traditional

buildings are made with clay or mud are not subject to

these regulations.

In the Regulations has been expressed on the main

issues in terms of architectural considerations and concerns

structural configuration and discuss torsion control and

avoid short columns and avoid the use of different

structural systems in various stretches in plan and

elevation. Buildings in terms of importance, shape and

structural systems were grouped and the equivalent static

analysis and dynamic analysis methods are used to

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calculate the earthquake forces. The equivalent static

analysis is used for the following:

A. Regular buildings with a height of less than 50 meters

from the base level

B. Irregular buildings up to 5 floors or with a height of less

than 8 meters from the base level

C. Buildings in which the upper part of lateral stiffness is

considerably less than the lower part of lateral stiffness,

provided that:

1. Each of the two is regular structures alone.

2. The medium hardness of the lower classes is at

least 10 times the average hardness of the upper

classes.

3. The fundamental period of oscillation of the

structure is not more than 1.1 times the upper

fundamental period, assuming that the separation is

intended and it’s been assumed tangly.

Dynamic analysis methods can be used on all of the

buildings, but to use them for buildings that are not subject

to the above conditions is required.

As in static analysis has been defined(the third edition

of the Regulations), by calculating the base shear force V

or the sum of forces in each of the extensions of the

earthquake, once the quake is calculated that factors such as

the earthquake factor C, the entire weight of building W,

the acceleration of the design basis A, the building

reflection coefficient B, the building importance factor I

and the building behavior coefficient R are involved

therein, and considering the base shear force should be

provided to meet V_min = 0.1 AIW or (B / R) _min = 0.1.

Then the calculated base shear force V is distributed in the

elevation of the building in conformity with the following

equation:









  































  , if T≤0.7sec →



 

This base shear force is also distributed in the plan of

the building. Then, the vertical force caused by the

earthquake which is the vertical component effect of the

earthquake acceleration in the building is considered in

computations in the following cases:

A. The beams that their span is more than 15 meters, with

columns and their wall support.

B. The beams that endure significantly concentrated

vertical in comparison with other loads transferred to

the beam comply with their wall support

C. In the case of a concentrated load is at least equal to

half the total load on the beam, it is considered to be a

significant burden.

D. Balconies and projections, which are constructed in the

form of cantilevers.

In addition to the equivalent static method, the

earthquake lateral force is determined by using the dynamic

analysis methods in which a dynamic reflection of the

structure shows the earth movement caused by the quake.

These methods include spectral analysis method and time

history analysis that the details have been described in the

Third Edition 2800 Code. The application of any of these

two methods in the buildings included this regulation is

optional. All the parameters that can be used in dynamic

analysis, such as mass, acceleration of the base and the

values that have defined the equivalent static analysis.

4 Differences and Changes in the New Design

Code for Buildings in Earthquake (Standard

No. 2800)

In the third edition of the Iranian Earthquake (Standard

No. 2800) design is carried out by AST method, While in

the fourth edition, the design is performed by LRFD

method and of the latest version of ASCE and regulations

of America's steel and concrete are applied to improve the

new edition and it is a combination of the Iran seismicity

circumstances and the quake experiences in the past.

It is discussed on the issues such as Geotechnical

considerations, the applicable limit of the Regulations and

discussing parts of the facade and other non-structural

components and other non-building structures.

On the building reflection coefficient formula B,

classification of seismic ground, the percentage turnout live

load and snow load and the period of oscillation T, lateral

force distribution earthquake in building height, the effect

of P-Δ, the relative lateral shift classes and the lateral

effects of the earthquake on the diaphragms, the new

edition of the Code of 2800 has undergone changes

concerning the conditions and formula.

On the calculation of seam discontinuity and grouping

of buildings, terms of use of the equivalent static analysis

method, the combination of the systems in height,

calculation of buildings against the reversal, vertical force

caused by the earthquake have been the changes in the

provisions discussed and also some new items have been

added to the fourth edition.

Regarding the issues such as irregular geometry in

height, the cantilever column system, structural uncertainty

coefficient ρ, added factor of resistance



, soil-structure

interaction effect and the simplified method for analyzing

and designing had not been proposed in the third edition of

the 2800 Code, while in the fourth edition the issues raised.

In this regard, lateral force of the earthquake on building

components and components Additional formula F

which

was presented in the third edition has been deleted in the

fourth edition and it is no longer used. Applying the

vertical force caused by the earthquake is mandatory in the

whole structures for buildings that are located in the zones

with very high risk. Considering the uncertainty regarding

the structure and additional resistance is determined by

applying specified coefficients.

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5 The Difference between Allowable Stress

Design Method (asd) & Final Resistance

(lrfd)

1. Elastic method: until 1950, these structures were

designed as per ASD or allowable stress design method

or in other words, designing the members of this type

steel structure took place in such a way that members

due to of the loads entered not to leave their elastic

limit. Using this method has had continued in most

countries of the world, including Iran and Iran's internal

regulations and the national building regulations was

developed as per this method.

2. Plastic method or plastic: from 1980, to enhance the

quality of materials and improve the quality of

implementation, plastic or ultimate strength LRFD

method was substituted as a more scientific & an

economical method in some countries with the elastic

method or ASD, so it has been conducted in the fourth

edition of the Iranian regulation against earthquake. In

this method (LRFD), the members of the constructions

will be allowed due to the load caused by the load of

the elastic out and reach to limit their plastic or plastic

and make it increase the strength members and reduce

construction cost and is a more economical structure.

In Iran by 2014, most of the buildings were designed by

the ASD design, however with the new edition of the 2015

earthquake regulations and regulations for the steel design

was based on the LRFD method.

6 Conclusions

After comparing the amounts obtained from the

resolution of various issues on the basis of both Editions of

the Regulations 2800, it can be realized that there are many

advantages In the analysis and design of structures against

earthquakes, according to the fourth edition (LRFD

method) compared to the analysis and design of structures

as per the third (ASD method) including that the load factor

in LRFD method is based on the assurance of occurring

them. For example, the live load factor to be considered

more than the dead load coefficient, as well as cost

reduction and optimal design of structures against

earthquakes by reducing the effective weight of the

structures and shear of classes is one of the fundamental

changes.

References

1. Regulation of Earthquake – Standard 2800 - Third

Edition 2005.

2. Regulations of Earthquake - Standard 2800 - Fourth

Edition 2014.

3. M. Azhari. M, Mir Bagheri. S. R, “Design of Steel

Structures”, Volume IV , Seismic design issues.

4. Tavakoli. H, Manaf poor, A R, “Comparison of seismic

regulations in Iran, Chile and America”, 2011.

5. Hemati. S, Kashefi. S, Gerami. M, “Comparison of the

spectrum seismic design codes in Iran, India, Japan and

Europe” 2012.