P e r u

Technical Building Standard E.030 Earthquake Resistant Standards （E-030 Diseño Sismorresistente (in Spanish)）

2003

Ministry of Housing, Construction and Sanitation

Editorial Note: According to the information provided by the national delegate, PeruvianStandard had major change in 1997 and was revised in 2003. It is current standard.

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Comments On Building Codes 1. General

a. Name of Country: Peru b. Name of Codes:

Earthquake-Resistant Design -- in English E-030 Diseño Sismorresistente (in Spanish) in Original Language

c. Issued by: Ministry of Housing, Construction and Sanitation d. Enforcement Year: 2003

2. Structural Design Method

a. Format: (please check) [ ] Working Stress Design : Allowable Stress ≧ Actual Stress [√] Ultimate Strength Design: Ultimate Member Strength ≧ Required Member Strength [ ] Limit State Design : Ultimate Lateral Strength ≧ Required Lateral Strength [ ] Other Design Method : (comment)

Standard applies only to buildings. Design is one phase only. Forces correspond to severe earthquake but reduced by R factor. This results in moderate strength, enough to resist light earthquakes, on the limit for moderate and accepted structural damage for severe earthquakes, but to avoiding collapse (although no procedure to enforce this is included). Load factor for seismic forces is unity Computed displacements with Code Factors require stiff structures to comply with allowable displacements. b. Material Strength (Concrete and Steel): Factored ultimate strength of members is used in the ultimate strength analysis procedure to evaluate the ultimate lateral load resistance of buildings Forces are factored by one. c. Strength Reduction Factors: Factors adapted from ACI and AISC standards are used in LRF Design d. Load Factors for Gravity Loadings and Load Combination: Factors adapted from ACI and AISC standards are used in LRF Design e. Typical Live Load Values:

Office Buildings : 2.5 kN/m2

Residential Buildings: 2.0 kN/m2

f. Special Aspects of Structural Design Method

Standard Ultimate Strength Design (LRFD)

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MINISTRY OF HOUSING, CONSTRUCTION AND SANITATION

TECHNICAL BUILDING STANDARD

E.030

“EARTHQUAKE-RESISTANT DESIGN”

Lima, April 02, 2003

Approved By Ministerial Decree N° 079-2003 VIVIENDA

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TECHNICAL BUILDING STANDARD E.030

PERMANENT TECHNICAL COMMITTEE NTE E-030 EARTHQUAKE-

RESISTANT DESIGN

Chairman: Dr. Javier Pique del Pozo Advisor Eng. Julio Kuroiwa Horiuchi Technical Secretary: SENCICO

MEMBERS

INSTITUTIONS REPRESENTATIVES Japan-Peru Centre for Earthquake Engineering Research and Disaster Mitigation (CISMID-UNI)

Dr. Javier Piqué del Pozo

South American Regional Center for Earthquake Engineering (CERESIS)

Dr. Jorge Alva Hurtado

Peruvian Board of Engineers. Lima Council

Dr. Hugo Scaletti Farina Eng. Luis Zegarra Ciquero

Geophysical Institute of Peru (IGP) Dr. Leonidas Ocola Aquise Pontifical Catholic University of Peru Eng. Alejandro Muñoz Peláez National University of Engineering (UNI). Faculty of Civil Engineering

Eng. Roberto Morales Morales

National Service for Research, Standards and Training for the Construction Industry (SENCICO)

Eng. Julio Kuroiwa Horiuchi Eng. Julio Rivera Feijóo

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CONTENTS Chapter 1. GENERAL

Article 1 Notation Article 2 Scope Article 3 Philosophy and principles of earthquake resistant design Article 4 Presentation of the project

Chapter 2. SITE PARAMETERS Article 5 Zonation Article 6 Local Conditions Article 7 Seismic Amplification Factor

Chapter 3. GENERAL REQUIREMENTS Article 8 General aspects Article 9 Concept of seismic resistant structures Article 10 Occupancy categories of buildings Article 11 Structural configuration Article 12 Structural systems Article 13 Category, structural system and regularity of buildings Article 14 Analysis procedures Article 15 Lateral displacements

Chapter 4. ANALYSIS OF BUILDINGS

Article 16 General Article 17 Static analysis Article 18 Dynamic analysis

Chapter 5. FOUNDATIONS

Article 19 General Article 20 Bearing capacity Article 21 Overturning moment Article 22 Isolated footings and caissons

Chapter 6. NONSTRUCTURAL ELEMENTS, APPENDAGES AND EQUIPMENT Article 23 General

Chapter 7. EVALUATION AND REPAIR OF STRUCTURES DAMAGED

BY EARTHQUAKES Article 24 General

Chapter 8. INSTRUMENTATION

Article 25 Recording accelerographs Article 26 Location Article 27 Maintenance Article 28 Data availability Article 29 Requirements for acceptance of Works

ANNEX Seismic macrozonation of Peru

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CHAPTER 1

GENERAL Article 1 Notation C Seismic amplification coefficient CT Coefficient to estimate the predominant period of a building Di Lateral elastic displacement of level "i" relative to ground e Accidental eccentricity Fa Horizontal force on the top roof Fi Horizontal force on level "i" g Acceleration due to gravity hi Height above the base to Level "i" hei Height of story "i" hn Total height in meters of building Mti Accidental torsional moment on level "i" m Number of modes used in modal superposition n Number of stories in the building Ni Sum of weights above level "i" P Total weight of the building Pi Weight of level "i" R Seismic forces reduction coefficient r Maximum expected elastic structural response ri Elastic responses corresponding to mode "i" S Soil factor Sa Acceleration spectrum T Fundamental period of the structure for static analysis or modal period

for dynamic analysis Tp Period that defines the spectrum platform for each type of soil U Use and importance factor V Base shear Vi Story shear in story "i" Z Zone factor Q Stability coefficient for overall P-delta effect ∆i Relative drift of story "i" Article 2 Scope This standard establishes the minimal conditions to ensure that buildings designed according to its requirements will have a seismic behaviour, in accordance to principles stated in Article 3. It applies to the design of all new buildings, to the evaluation and reinforcing of existing buildings, and to the repairing of buildings that have sustained earthquake damage. In case of special structures, such as reservoirs, tanks, silos, bridges, transmission towers, docks, hydraulic structures, nuclear plants, and all those

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structures whose dynamic behaviour differs from that of conventional buildings, additional considerations are required as a supplement to the basic guidelines contained herein. In addition to the standards contain herein prevention measures must be taken against disasters that may occur as a consequence of seismic movements: fire, leak of hazardous materials, massive landslides and others. Article 3 Philosophy and Principles of Earthquake Resistant Design The philosophy of earthquake resistant design consists of: a) to avoid human life casualties b) to ensure continuity of vital services c) to minimize damage to property It is recognized that to give complete protection against all earthquakes is not technically neither economically feasible for most structures. In accordance with this philosophy the following design principles are established: a) The structure should not collapse nor harm human beings by severe

earthquake ground motions that could occur at the site. b) The structure should withstand moderate earthquake ground motions

which may be expected to occur at the site during service life of the structure with damage within acceptable limits.

Article 4 Presentation of the Structural Project The drawings, description, and technical specifications of the structural project shall be signed by a chartered civil engineer (a civil engineer registered at the Peruvian Board of Engineers), who shall be the only person authorized to approve any modification to the above-mentioned documents. The specifications and the drawings for the structural project shall contain at least the following information: a) Earthquake-resistant structural system b) Parameters to define the seismic force or the design spectrum c) Maximum displacement of the uppermost level and maximum relative

interstory displacement. Projects for buildings over 70m in height shall be backed up with a report containing data and justifying calculations to be reviewed and approved by the concerned authorities. The use of materials, structural systems and construction methods other than those indicated in this Standard shall be approved by the concerned authorities appointed by the Ministry of Housing, Construction and Sanitation,

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and such materials, systems and methods must comply with the provisions of this section and it must be demonstrated that the proposed solution will produce adequate results in terms of stiffness, seismic resistance, and durability.

CHAPTER 2

SITE PARAMETERS Article 5 Zonation The country is considered to be divided into three zones, as shown in Figure N° 1. The proposed zonation is based on the spatial distribution of the seismicity observed, the general characteristics of the seismic movements, and their attenuation with the epicentral distance; and also on neotectonics data.

Each zone has a Z factor allocated to it, as shown in Table 1. This factor is interpreted as the maximum ground acceleration that has a 10% probability of exceedence in 50 years.

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Table 1 Zone Factors

ZONE Z 3 0.40 2 0.30 1 0.15

Article 6 Local Conditions 6.1 Seismic microzonation and site studies a. Seismic microzonation This involves multidisciplinary studies which investigate the effects of seismic movements and associated phenomena such as soil liquefaction, landslides, tsunamis, etc., on the area of interest. The studies supply information on the possible modification of the seismic actions by local conditions and other natural phenomena, as well as the limitations and demands that, as a result of the studies, are taken into account for the design and construction of buildings and other works. It shall be a mandatory requisite that microzonation studies be carried out in the following cases: • Urban expansion areas • Industrial complexes, or similar • Reconstruction of urban areas destroyed by earthquakes and associated

phenomena. The results of microzonation studies shall be approved by the concerned authorities, who may request additional information or justification if they deem it necessary. b. Site studies They are similar to microzonation studies, although not necessarily so extensive. These studies are limited to the project site, and they supply information on the possible modification of seismic actions and other natural phenomena by local conditions. Their main objective is to determine the design parameters. Design parameters below those indicated in this Code shall not be taken into consideration. 6.2 Geotechnical Conditions For the effects of this Standard, soil profiles shall be classified taking into account the mechanical properties of the soil, the depth of the stratum, the

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fundamental vibration period and the velocity of propagation of the shear waves. There are four soil profile types: a) Type S1 profile: Rock, or very rigid soils.

This group includes rocks and very rigid soils with a shear wave propagation velocity similar to that of rock, in which the fundamental period for low amplitude vibrations does not exceed 0.25 s, including the cases in which foundations are on: • Sound or partially altered rock, with a resistance to non-confined

compression of 500 kPa (5 kg/cm2) or more. • Dense sandy gravel. • Stratum of no more than 20 m of very rigid cohesive material, with a

shear resistance under undrained conditions of more than 100 kPa (1 kg/cm2), on rock or another material with a shear wave propagation velocity similar to that of a rock.

• Stratum of no more than 20 m of very dense sand with N > 30, on rock or another material with a shear wave propagation velocity similar to that of a rock.

b. Type S2 profile: Intermediate soils.

Soils classified in this group are those belonging to the sites whose characteristics fall between those indicated for S1 profile and for S3 profile.

c. Type S3 profile: Flexible soils or those with very deep strata.

This group contains flexible soils or strata of great depth in which the fundamental period, for low amplitude vibrations, is over 0.6 s, including those cases in which the depth of the soil stratum exceeds the following values:

Cohesive soils Shear resistance typical in undrained condition (kPa)

Depth of stratum (m) (*)

Soft Moderately compact Compact Very compact

< 25 25-50

50-100 100-200

20 25 40 60

Granular soils N typical values in standard penetration tests (SPT)

Depth of stratum (m) (*)

Loose Moderately dense Dense

4-10 10-30

over 30

40 45

100 (*) Soil with shear wave velocity lower than that of a rock

d. Type S4 profile: Exceptional conditions This group includes exceptionally flexible soils and sites where the geological and/or topographical conditions are particularly unfavourable.

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The type of profile that best describes the local conditions should be considered, using the corresponding values of Tp and of the soil amplification factor, S, shown in Table 2. On the sites where the soil properties are unknown, the values corresponding to S3 profile type may be used. An S4 profile type need only be considered when the geotechnical studies so indicate.

Table 2 Soil Parameters

Type Description Tp (s) S S1

Rock or very rigid soils 0.4 1.0

S2

Intermediate soils 0.6 1.2

S3 Flexible soils, or those with very thick strata

0.9 1.4

S4 Exceptional conditions * * (*) The values of Tp and S for this case shall be established by the expert, but under no circumstances shall they be lower than those specified for S3 profile type.

Article 7 Seismic Amplification Factor According to the site characteristics, the seismic amplification factor (c) is defined by the following formula:

5.2*5.2 ≤⎟⎠⎞

⎜⎝⎛= C

TTpC

T is the period after it is defined in Article 17 (17.2) or in Article 18 (18.2) This coefficient is interpreted as the amplification factor of the structural response respect to ground motion.

CHAPTER 3

GENERAL REQUIREMENTS Article 8 General considerations All buildings and each one of their parts shall be designed and built to withstand seismic forces as determined in this Code. Consideration shall be given to the possible effect of the nonstructural elements in the seismic behaviour of the structure, and the analysis and specification of the reinforcement and anchoring shall be performed in keeping with this consideration.

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For regular structures, analysis may be made considering the total of the seismic force acting independently in two orthogonal directions. For irregular structures the most unfavourable direction for design of each element or component under study must be used for seismic action. Vertical seismic force shall be considered to act on the elements simultaneously with the horizontal seismic force, and in the most unfavourable direction for the analysis. It is not necessary to consider simultaneously the effects of earthquake and wind. When one single element of the structure, wall or frame resists a force of 30% or more of the total horizontal force at any level, this element shall be designed for 125% of said force. Article 9 Seismic resistant structural concepts The seismic behaviour of a building shall be considered to improve when the following conditions are observed: • Symmetry, both in the distribution of masses and stiffnesses. • Minimal weight, especially on the upper stories. • Selection and adequate use of the building materials. • Adequate resistance. • Continuity in the structure, both in plan and in elevation. • Ductility, as an indispensable requisite for satisfactory seismic behaviour. • Limited deformation, since otherwise the damage to nonstructural

elements could be out of proportion. • Inclusion of successive lines of resistance. • Consideration of the local soil conditions in the project. • Good construction practice and rigorous inspection of structure. Article 10 Building Categories Each structure shall be classified according to the categories indicated in Table 3. Depending on the classification made, the use and importance coefficient (U) defined in the following table shall be used.

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Table 3

OCCUPANCY CATEGORIES OF BUILDINGS CATEGORY DESCRIPTION U FACTOR

A

Essential buildings

Essential buildings whose function should not be interrupted upon occurrence of an earthquake -- such as hospitals, communication facilities, fire stations, police stations, electricity substations, water reservoirs; schools and other buildings that can be used as places of refuge after a disaster. Other buildings included in this group are those whose collapse could pose an additional risk, such as large furnaces, and warehouses where inflammable or toxic materials are stored.

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B

Important buildings

Buildings where a large number of people gather -- such as theatres, stadiums, malls, prisons; or buildings with valuable contents, such as museums, libraries, and special archives. Granaries and other storehouses important for supplies are also considered in this group.

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C

Common buildings

Common buildings, whose failure would cause medium losses -- houses, offices, hotels, restaurants, warehouses and industrial installations, whose failure would not result in additional dangers of fire, leakage of pollutants, etc.

1.0

D Minor

buildings

Buildings, whose failure would cause smaller losses, and where normally the likelihood of causing victims is low, such as fences lower than 1.50 m, temporary storehouses, small temporary living units, and similar constructions.

(*)

(*) In these buildings, the project designer may make the decision to omit the analysis for seismic forces, but adequate resistance and stiffness must be provided for lateral actions. Article 11 Structural configuration Structures shall be classified as regular or irregular in order to determine the proper analysis procedure and appropriate values of the seismic force reduction factor (Table 6). a. Regular structures. Structures that have no significant horizontal or vertical discontinuities in their lateral-force-resisting configuration. b. Irregular Structures are defined as those that present one or more of the characteristics mentioned in Tables 4 or 5.

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Table 4

STRUCTURAL IRREGULARITIES IN VERTICAL CONFIGURATION

Stiffness-related irregularities - Soft story. In each direction the sum of the areas of the transverse sections of the vertical elements resistant to shear in the story, columns and walls, is less than 85% of the corresponding sum for the story above, or less than 90% of the average for the 3 upper stories. Not applicable in basements. For stories of different height the former values must be multiply by (hi/hd), where hd is the different height and hi is the typical story height. Irregularity of mass - Mass irregularity is considered to exist when the mass of one floor is more than 150% of the mass of an adjacent floor. Not applicable on roofs. Vertical geometric irregularity - The dimension in plan of the lateral-load-resistant structure is more than 130% of the corresponding dimension on an adjacent floor. Not applicable on roofs or in basements. Discontinuity in the Resisting Systems - Disalignment of vertical elements, due both to a change of direction, and to a displacement of greater magnitude than the dimension of the element.

Table 5 STRUCTURAL IRREGULARITIES IN PLAN

Torsional irregularity This shall be considered only in buildings with rigid diaphragms in which the average displacement of any interstory exceeds 50% of the maximum allowable indicated in Table N° 8 of Article 15 (15.1). In each of the directions of analysis, the maximum relative displacement between two consecutive floors is greater than 1.3 times the average if this maximum relative displacement with the relative displacement that simultaneously occurs in the opposed end. Re-entrant corners The configuration in plan and the structure's resisting system have re-entrant corners, whose dimensions in both directions are more than 20% of the corresponding total dimension in plan. Discontinuity of the diaphragm Diaphragm with sudden discontinuities or variations in stiffness, including open areas larger than 50% of the gross area of diaphragm.

Article 12 Structural systems The structural systems are classified according to the materials used and the predominant seismic-resistant structural predominant in each direction, as indicated in Table 6.

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After the classification is made a seismic force reduction coefficient (R) will be used. For ultimate strength design internal seismic forces must be combined with factors of one. On the contrary, values of Table 6 can be used if previously multiply by the corresponding seismic load factor.

Table 6 STRUCTURAL SYSTEMS

Structural system Reduction coefficient (R)for regular structures (*) (**)

Steel Ductile frames: with moment resisting joints Other Steel Structures Excentric bracing Cross bracing

9.5

6.5 6.0

Reinforced Concrete Frames (1) Dual (2) Structural walls (3) Limited ductility walls (4)

8 7 6 4

Reinforced and confined masonry(5)

3

Wooden constructions (working stress design)

7

(1) System in which at least 80% of base shear is resisted by columns of frames designed accordingly to NTE E.060 “Reinforced Concrete”. In case there are structural walls they should be designed to resist the fraction of total seismic action accordingly to its stiffness. (2) System in which the seismic actions are resisted by a combination of reinforced concrete frames and structural walls. Frames shall be designed to take at least 25% of the base shear. (3) System in which the seismic resistance is provided basically by reinforced concrete structural walls which resist at least 80% of base shear (4) Low rise building with high density of limited ductility walls (5) For working stresses design R would be 6 (*) These coefficients shall be applied only to structures in which the vertical and horizontal elements allow the dissipation of energy while maintaining the stability of the structure. (**) For irregular structures, the values of R shall be taken as 3/4 of those noted in the Table. For earthen constructions, refer to Technical Building Standard E.080. This type of construction is not recommended on S3 soils, and it is not allowed on S4 soils. Article 13 Category, structural system and regularity of buildings According to the category of a building and the zone it is located in, the building should be planned observing the characteristics of regularity and using the structural system indicated in Table 7.

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Table 7

CATEGORY AND STRUCTURE OF BUILDINGS Category

of BuildingStructural Regularity

Zone Structural System

3

Steel, Reinforced concrete walls, Reinforced or confined masonry, Dual system

A

(*) (**)

Regular

2 and 1

Steel, Reinforced concrete walls, Reinforced or confined masonry, Dual system, Wood

3 and 2

Steel, Reinforced concrete walls, Reinforced or confined masonry, Dual system, Wood

B

Regular or Irregular

1 Any system C Regular or

Irregular

3, 2 and 1 Any system

(*) To meet the objectives indicated in Table 3, the building shall be especially structured to resist strong earthquakes. (**) For small rural constructions, such as schools and health centers, traditional building materials may be used providing that the recommendations of the standards on such materials are followed. Article 14 Analysis procedures 14.1 Any structure may be designed using the results of the dynamic

analyses referred to in Article 18. 14.2 Only structures qualifying as regular pursuant to Article 10 and no

higher than 45m and bearing wall structures no higher than 15m may be analysed by the equivalent static force procedure described in Article 17.

Article 15 Lateral Displacements 15.1 Allowable lateral displacements The maximum relative story drift, calculated according to Article 16 (16.4), must not exceed the fraction of the story height indicated in Table 8.

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Table 8 ALLOWABLE STORY DRIFT

These limits are not applicable to industrial naves Predominant Material (∆i/hei)

Reinforced concrete 0.007 Steel 0.010 Masonry 0.005 Wood 0.010

15.2 Seismic separation joint All structures shall be separated from adjoining structures by a minimum distance ("s") to prevent contact during a seismic event. This minimum distance shall not be less than 2/3 of the sum of the maximum displacements of the adjacent blocks, nor shall it be less than: s = 3 + 0.004(h-500) (h and s in cm) s > 3 cm. where: h = the height measured from ground level to the level

considered for evaluating s. The building shall be set back from adjacent property lines of empty plots that can be built on or from existing buildings, by distances no less than 2/3 of the maximum displacement calculated according to Article 16 (16.4), nor less than s/2. 15.3 Stability of the building The effect of eccentricity of the vertical load produced by the building's lateral displacements (P-delta effect) should be taken into consideration as described in Article 16 (16.5). The stability against overturning of the whole shall be verified as indicated in conformity with Article 21.

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CHAPTER 4

ANALYSIS OF BUILDINGS Article 16 General 16.1 Seismic forces and analyses In keeping with the earthquake-resistant design philosophy, it is accepted that the buildings will have inelastic incursions in response to severe seismic actions. Therefore the design seismic forces are considered as a fraction of the maximum elastic seismic forces. Analysis may be performed using the reduced seismic forces with an elastic behaviour model for the structure. 16.2 Models for analysis of buildings Model for analysis shall consider a spatial distribution of masses and rigidities suitable for calculating the most significant aspects of the structure's dynamic behaviour. For buildings in which it can reasonably be assumed that the floor systems function as rigid diaphragms, a model may be used with concentrated masses and three degrees of freedom per diaphragm, associated to two orthogonal components of horizontal movement and one rotation. In this case, the deformations of the elements must be made compatible using the rigid diaphragm condition, and the distribution in plan of the horizontal forces must be made based on the stiffnesses of the resisting elements. It must be verified that the diaphragms have sufficient stiffness and strength to ensure the mentioned distribution, otherwise their flexibility must be taken into account when calculating the distribution of the seismic forces. In case the floors do not constitute rigid diaphragms, the resisting elements shall be designed for the horizontal forces directly corresponding to them. 16.3 Weight of the building The weight (P) shall be calculated by adding to the permanent total load of the building a percentage of the live load or surcharge that shall be determined in the following way:

a) In category A and B buildings, 50% of the live load shall be considered.

b) In category C buildings, 25% of the live load shall be considered. c) In storage buildings, 80% of the total weight that can be stored shall

be considered. d) On all roofs, 25% of the live load shall be considered.

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e) In tanks, silos, and similar structures, 100% of the load they can contain shall be considered.

16.4 Lateral displacements Lateral displacements shall be calculated multiplying by 0.75R the results obtained from the linear and elastic analysis with the reduced seismic forces. For calculation of the lateral displacements the minimum values of C/R indicated in Article 17 (17.3) nor the minimum base shear indicated in Article 18 (18.2d) shall not be taken into account. 16.5 Secondary (P-Delta) effects The secondary effects shall be considered whenever they produce an increase of more than 10% in the internal forces. In order to estimate the importance of the secondary effects, the following quotient may be used for each level as a stability index:

RhVNQ

eii

ii∆=

Secondary effects shall be taken into account when Q > 0.1. 16.6 Vertical seismic loads These loads shall be considered in the design of vertical elements; in post- or pre-stressed elements and in the cantilevers or projections of a building. Article 17 Static Analysis 17.1 General This method represents the seismic forces by means of a set of horizontal forces acting at each level of the building. It should be used only for buildings with no irregularities and of low height, as described in Article 14 (14.2). 17.2 Fundamental period (a) Fundamental period for each direction shall be estimated using the

following formula:

T

n

Ch

T =

where:

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CT = 35 for buildings whose force-resisting elements in the direction under consideration are frames only.

CT = 45 for reinforced concrete building whose force-resisting elements are frames, elevator shafts and stair wells.

CT = 60 for masonry structures and for all reinforced concrete building whose force-resisting elements are basically shear walls.

(b) A dynamic analysis procedure which considers the characteristics of

stiffness and distribution of masses in the structure may also be used. As a simple form of this procedure, the following expression can be applied:

T = 2π

⎟⎟⎠

⎞⎜⎜⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛

∑

∑

=

=

n

i

n

i

DiFig

DiPi

1

1

2

Whenever dynamic procedure does not consider the effect of the nonstructural elements, the fundamental period must be taken as 0.85 of the value obtained by this method. 17.3 Base shear Total shear in the base of the structure, in a given direction, shall be determined from the following formula:

PR

ZUSCV =

where the following minimum value for C/R should be considered:

125.0/ ≥=RC

17.4 Vertical distribution of earthquake shear force If the fundamental period, T, is longer than 0.7 seconds, a part of the shear V, called Fa, must be applied as a concentrated force on the upper part of the structure. This force Fa shall be determined using the following formula:

VTVFa 15.007.0 ≤= where the period T in the foregoing formula shall be the same as that used to determine the base shear.

The rest of the shear, in other words V-Fa, shall be distributed among the different levels, including the uppermost one, in accordance with the following formula:

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( )an

j

i FVhjPj

hiPiF −∑

=

= 1

17.5 Torsional effects The force at each level (Fi) shall be assumed to be acting on the centre of mass of the respective level. In addition, the effect of accidental eccentricities must be taken into account, as indicated below. For each direction under analysis, the accidental eccentricity at each level (e) shall be calculated as 0.10 times the dimension of the building in the direction perpendicular to the direction of application of the forces. At each level, besides the acting force, the accidental moment called Mti shall be applied, calculated as:

iii eFMt ±= It may be assumed that the most unfavourable conditions are obtained considering the accidental eccentricities with the same sign in all the levels. Only increments in horizontal forces shall be considered not reductions. 17.6 Vertical seismic forces The vertical seismic force shall be considered as a fraction of the weight. For Zones 3 and 2 this fraction shall be 0.3. For Zone 1, this effect need not be taken into consideration. Article 18 Dynamic analysis 18.1 Scope Dynamic analysis of buildings may be performed using modal spectral combination procedures or time-history analyses. For conventional buildings, the spectral combination procedure may be used; and for special buildings a time-history analysis must be used. 18.2 Spectral combination analysis a. Vibration modes The natural periods and vibration modes may be determined using an analysis procedure which takes proper account of the characteristics of stiffness and the distribution of the masses of the structure. b. Spectral acceleration

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For each of the horizontal directions analysed, an inelastic spectrum of pseudo-accelerations shall be used, defined by:

gR

ZUSCSa =

For the analysis in the vertical direction, a spectrum with values equal to 2/3 of the spectrum employed for the horizontal directions may be used. c. Combination criteria When use of the combination criteria indicated below it will be possible to obtain the maximum expected response (r) both for the internal forces in the structure's component elements, and for the overall parameters of the building, such as base shear, story shear, overturning moments, and total and relative story displacements. The maximum expected elastic response (r) corresponding to the combined effect of the different modes of vibration employed (ri) may be determined using the following formula:

( )∑ ∑+== =

m

i

n

iii rrr

1 1

275.025.0

Alternatively, the maximum response may be estimated by means of a complete quadratic combination of the values calculated for each mode. In each direction those modes of vibration whose sum of effective masses is at least 90% of the mass of the structure shall be considered, but at least the first three predominant modes in the direction under analysis must be taken into account. d. Minimum base shear For each of the directions included in the analysis, the building's base shear must not be less than 80% of the value calculated as described in Article 17 (17.3) for regular structures, and it must not be less than 90% for irregular structures. If it is necessary to increase the shear to comply with the indicated minimums, all the other results obtained must be scaled proportionally, except displacements. e. Torsional effects Uncertainty in the location of the centers of mass at each level shall be incorporated by means of an accidental eccentricity perpendicular to the direction of the earthquake equal to 0.10 times the dimension of the building in the direction perpendicular to the direction under analysis. In each case the most unfavourable sign must be considered.

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18.3 Time-history analysis Time-history analysis may be carried out assuming linear and elastic behaviour, and no less than five records of horizontal accelerations must be used, corresponding to real or artificial acceleration records. These records shall be standardised in such a way that the maximum ground motion corresponds to the maximum expected value at the site. For particularly important buildings, the dynamic time-history analysis shall be performed considering inelastic behaviour of the elements of the structure.

CHAPTER 5

FOUNDATIONS Article 19 General The assumptions made for the structure supports shall be in concordance with the characteristics of the foundation soil. The design of the foundations shall be compatible with the distribution of forces obtained from analysis of the structure. Article 20 Bearing capacity All soil mechanics studies shall include the effects of seismic movements for the determination of the bearing capacity of the foundation soil. In sites where soil liquefaction could occur, a geotechnical investigation shall be made to evaluate this possibility and determine the most appropriate solution. For the calculation of the admissible pressures on the foundation soil under seismic actions, the minimum safety factors indicated in Technical Building Standard E-050 "Soils and Foundations" shall be used. Article 21 Overturning moment All structures and their foundation shall be designed to resist the overturning moment produced by an earthquake. The safety factor shall be 1.5 or more. Article 22 Isolated footings and caissons For isolated footings with or without piles in soil profiles S3 and S4 and for Zones 3 and 2, connecting elements shall be provided, which must support,

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in tension or compression, a minimum horizontal force equal to 10% of the vertical load borne by the footing. In the case of piles and caissons connecting beams shall be provided; or the overturning and deformations caused by horizontal force shall be taken into account and piles and footings must be built for these stresses. The piles shall be considered to have reinforcement in tension equivalent to at least 15% of the vertical load they support.

CHAPTER 6

NONSTRUCTURAL ELEMENTS, APPENDAGES AND EQUIPMENTS Article 23 General Elements which, regardless of whether or not they are connected to the horizontal-force-resisting elements, provide a negligible contribution to the system's stiffness are considered nonstructural elements. In the event that the nonstructural elements are isolated from the principal structural system, they shall be designed to resist a seismic force (V) associated with their weight (P), as indicated below:

PZUCV 1=

The values of U correspond to those indicated in Chapter 3, and the values of Ci shall be taken from the following table:

Table 9 VALUES OF C1

Elements which when failing can fall outside the building in which the direction of the force is perpendicular to their plane.Elements whose failure implies a threat for individuals or other structures.

1.3

Walls inside a building (direction of force perpendicular to plane).

0.9

Fence walls. 0.6 Tanks, towers, lettering and chimneys connected to a part of the building considering the force in any direction.

0.9

Floors and roofs that act as diaphragms with the direction of the force in their plane.

0.6

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For nonstructural elements attached to the principal structural system and which should accompany the deformation of the principal structural system, it shall be ensured that in the event of failure they will not cause bodily harm. Connection of equipment and installations within a building shall be the responsibility of the concerned specialist. Each specialist shall guarantee that the equipment and installations do not represent a risk during an earthquake and, in the case of essential installations, he or she shall guarantee the continuity of the building's functions.

CHAPTER 6

EVALUATION AND REPAIR OF STRUCTURES DAMAGED BY EARTHQUAKES

Article 24 General Structures damaged by earthquakes shall be evaluated and repaired in such a way as to correct possible structural defects that produced the failure and to recover the capacity to withstand a future seismic event, in accordance with the objectives of earthquake-resistant design noted in Chapter 1. Once the earthquake has occurred, the structure shall be evaluated by a civil engineer, who shall determine whether the state of the building calls for reinforcement, repairs, or demolition. The study shall necessarily include the geotechnical features of the site. Repair work must be able to give the structure the right combination of stiffness, resistance and ductility to guarantee its good behaviour in future seismic events. The repair or reinforcement project shall include the details, procedures and building systems to be followed. For seismic repair and retrofitting of existing buildings criteria different than those indicated in this standard may be used, with due justification and approval from the concerned authorities.

CHAPTER 8

INSTRUMENTATION Article 25 Recording accelerographs

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In all seismic zones, all buildings projects with an area equal to, or greater than, 10,000 m2, shall be equipped with at least one recording accelerographs. Article 26 Location The instruments shall be placed in a room of at least 4m2 located in the lower level of the building, bearing in mind that they must be easily accessible for maintenance purposes, and must have suitable lighting, ventilation, electricity supply, physical security and should be clearly identified in architectural drawings. Article 27 Maintenance Operative maintenance, parts and components, consumable supplies, and service of the instruments shall be provided by the owners of the building under the supervision of the Peruvian Geophysical Institute. This responsibility shall remain in force for ten years. Article 28 Data availability The accelerograms recorded by the instruments shall be processed by the Peruvian Geophysical Institute and incorporated into the National Geophysical Data Bank. This information is in the public domain and shall be available to users at request. Article 29 Requirements for Acceptance of Works In order to obtain approval of works, and under the responsibility of the concerned official, the owner of the building shall present a certificate of installation, issued by the Peruvian Geophysical Institute, as well as a contract for the service of operational maintenance of the instruments.

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ANNEX SEISMIC MACROZONATION Seismic zones in which the Peruvian territory has been divided, for use with this Standards is shown in Figure 1 of Article 5. In what follows provinces of each zone are listed.

Zone 1 1. Department of Loreto. Provinces of Mariscal Ramón Castilla, Maynas y Requena. 2. Department of Ucayali. Province of Purús. 3. Department of Madre of Dios. Province of Tahuamanú. Zone 2 1. Department of Loreto. Provinces of Loreto, Alto Amazonas y Ucayali . 2. Department of Amazonas. All Provinces. 3. Department of San Martín. All Provinces. 4. Department of Huánuco. All Provinces. 5. Department of Ucayali. Provinces of Coronel Portillo, Atalaya y Padre Abad. 6. Department of Pasco. All Provinces. 7. Department of Junín. All Provinces. 8. Department of Huancavelica. Provinces of Acobamba, Angaraes, Churcampa, Tayacaja y Huancavelica. 9. Department of Ayacucho. Provinces of Sucre, Huamanga, Huanta y Vilcashuamán. 10. Department of Apurimac. All Provinces. 11. Department of Cusco. All Provinces. 12. Department of Madre of Dios. Provinces of Tambopata y Manú. 13. Department of Puno. All Provinces. Zone 3 1. Department of Tumbes. All Provinces. 2. Department of Piura. All Provinces. 3. Department of Cajamarca. All Provinces. 4. Department of Lambayeque. All Provinces. 5. Department of La Libertad. All Provinces. 6. Department of Ancash. All Provinces. 7. Department of Lima. All Provinces. 8. Constitutional Province of Callao. 9. Department of Ica. All Provinces. 10. Department of Huancavelica. Provinces of Castrovirreyna y Huaytará. 11. Department of Ayacucho. Provinces of Cangallo, Huanca Sancos, Lucanas, Víctor Fajardo, Parinacochas y Paucar of Sara Sara. 12. Department of Arequipa. All Provinces. 13. Department of Moquegua. All Provinces. 14. Department of Tacna. All Provinces.

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