“Anti-seismic Building Code Dissemination Housing Earthquake Safety Initiative (HESI)” UNCRD-Hyogo
PERUVIAN EXPERIENCE ON SEISMIC STANDARDS
Prof. Javier R. Piqué President, Peruvian Permanent Committee for Seismic Design Dean of the Board of Engineers of Peru-CD Lima
Evolution of Peruvian Seismic UNCRD-Hyogo Standards
1964: First project of Peruvian Standard based on SEAOC 1970: First Peruvian Standard nationwide (Lima 1966, Chimbote-Huaraz 1970)
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
1 UNCRD-Hyogo HUARÁZ 1970
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Evolution of Peruvian Seismic UNCRD-Hyogo Standards
1977: Second Peruvian Standard (After earthquakes of Chimbote–Huaraz 1970, Lima 1974)
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
2 “Anti-seismic Building Code Dissemination Housing Earthquake Safety Initiative (HESI)” UNCRD-Hyogo
NAZCA Earthquake November 1996
Buildings design with 1977 Standard
School Fermín del Castillo UNCRD-Hyogo
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
3 School building UNCRD-Hyogo
NAZCA 1996 Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Short column detail
UNCRD-Hyogo
NAZCA 1996
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
4 Allowable Displacements = DamageUNCRD-Hyogo
LAB BUILDING
Earthquake in X direction Maximum Displacements (RNC-1977)
Displacements (cm) Drift FLOOR x y x y 2do floor 6.494 0.000 1/144 < 1/5000 1er floor 4.091 0.013 1/90 < 1/5000
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Classrooms:
ALLOWABLE DISPLACEMENTS = DAMAGEUNCRD-Hyogo
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
5 Evolution of Peruvian Seismic UNCRD-Hyogo Standards
1997: Third Peruvian Standard. (After Nazca earthquake of 1996, Mexico 1985, Loma Prieta 1989, Northridge 1994, Kobe 1995) 2003: Revision of 3rd Standard
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Contributions of 1997 Seismic Code, maintained in 2003 Code UNCRD-Hyogo
Quantification de irregularities Reduction of allowable distortions Increase design intensities Declaration to try to “Avoid collapse” Regular structural configuration required for essential buildings
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
6 3.6 Category, Structural System and Regularity UNCRD-Hyogo
CATEGORY and STRUCTURAL SYSTEM OCCUPANCY STRUCTURAL Seismic Structural System CATEGORY REGULARITY Zone 3 Steel Frames Reinforced concrete shear walls Reinforced and confined masonry Dual system A REGULAR 2 Y 1 Steel frames (*) (**) Reinforced concrete shear walls Reinforced and confined masonry Dual system Timber B 3 Y 2 Steel frames Reinforced concrete shear walls REGULAR OR Reinforced and confined masonry IRREGULAR Dual system Timber 1 Any system C REGULAR OR 3, 2 Y 1 Any system. IRREGULAR
(*) To comply with design objectives buildings will be specially structured to resist severe earthquakes (**) Rural constructions may use traditional materials according to specific Codes.
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
1997 = Change of Standars UNCRD-Hyogo
V = Base shear
V earthquake= Elastic Behavior V=ZUSC
R
V design Inelastic Behavior
ZUSC ∆ (Lateral V= P ∆ analysis ∆ actual Displacement) R
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
7 Comparison between base shear coefficients UNCRD-Hyogo Seismic Standard 1977 1997 factor Z 1 0.4 factor U 1 1 factor S 1 1 factor C (short periods) 0.4 2.5 ZUCS 0.4 1 To obtain similar base shear, R factors had to be increased: 2,5 times Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Drift Limits were also reduced UNCRD-Hyogo
Standard 1977 1997 Increment of demand PREDOMINANT ∆ I ∆ ∆ I 77 hei −1 ⋅100 MATERIAL hei ∆ 97 Reinforced 0.010 0.007 43% Concrete Steel (*) 0.015 0.010 50% Masonry 0.010 0.005 100% Timber 0.015 0.010 50%
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
8 Same strength larger displacements UNCRD-Hyogo
V Same design level, 1977 and 1997
K1977
K1977
Displacements 1997 = 2.5 x 4/3= 3.33 times larger and compared against a stringent drift Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Espectro de Diseño UNCRD-Hyogo
4.0
3.5 Tipo S3 3.0 Tp=0.9 seg
2.5
CS Tipo S2 2.0 Tp=0.6 seg
1.5
Tipo S1 1.0 Tp=0.4 seg
0.5
0 0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination ExpertPeriodo Meeting – UNCRD-KOBE-2007 de Vibración, T (s)
9 “Anti-seismic Building Code Dissemination Housing Earthquake Safety Initiative (HESI)” UNCRD-Hyogo
ATICO (Arequipa) Earthquake
JUNE 2001
ATICO Earthquake, Southern PERU
23 June 2001 - Magnitude MS 8.2, Mw=8,4 UNCRD-Hyogo
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
10 TIME HISTORY of CORRECTED ACCELERATIONS PEAK GROUND ACCELERATION : 295.3 cm/seg2 (300 km from epicenter) UNCRD-Hyogo
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
1977 Standard: Allowable Displacements =
damage UNCRD-Hyogo
Photo: E. Fierro Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
11 1997 Standard = Stiffer structures. Regular structural system mandatory = No damage UNCRD-Hyogo
Photos E. Fierro
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
2003 version UNCRD-Hyogo
Ultimate strength. Base shear x 1.25 Displacements slightly reduced More “R” values Slight change in design spectrum descend
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
12 Design Philosophy 2003 Standard UNCRD-Hyogo
• a. Avoid loss of life • b. Ensure continuity of basic services • c. Minimize property damage.
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
Current Limitations of Standard UNCRD-Hyogo
One set of objectives, independent of building importance Seismic Performance level is combined with design seismic level, expresed as intensities Only one set of forces correpondiong to severe earthquake reduced by R to satisfy three performance levels.
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
13 CONCLUSIONS 1 UNCRD-Hyogo
All school buildings in Southern Peru designed with 1977 Standard experienced structural and nonstructural damage whereas none of the schools designed and built under the 1997 Standard experienced damage. Peruvian Seismic Standards requires higher computed lateral displacements. Structures have to be much more rigid than before.
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
CONCLUSIONS 2 UNCRD-Hyogo
Changes in structural element dimensions to achieve additional stiffness in case of school buildings increase structural costs by 30%. No cost was involved after the earthquake because of absence of damage.
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
14 CONCLUSIONS 3 UNCRD-Hyogo Structures designed with 1977 Standards had to be repaired, they could not be used for several months and cost of retrofitting and stiffening reach up to 40% of initial cost It is recommended Codes should incorporate: Ê Restrict displacements Ê Limit irregularities severely. Essential buildings should be regular Ê Either assure safe collapse mechanisms or limit use of frame systems alone
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
CONCLUSION UNCRD-Hyogo
Implement programs to support retrofitting with training and long term credit or subsidies Non-engineered heavy housing in high intensities areas should be relocated Emphasize importance of configuration Assure stable mechanism on ultimate conditions (Capacity design) Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
15 POSIBLE FUTURE CHANGES UNCRD-Hyogo
Performance based design: Several design levels Modification de load factors Determination of ultimate lateral resistance Definition de stable energy dissipation mechanisms :capacity design Energy Dissipation devices
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
PENDING AGENDA UNCRD-Hyogo
Convince users of benefit of good design Convince policy makers is less costly to invest in prevention trough retrofitting Introduce collapse prevention in design stage Implement policies for non engineered housing
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
16 UNCRD-Hyogo
GraciasGracias
Thanks to you all
Housing Earthquake Safety Initiative (HESI): Anti-seismic Building Code Dissemination Expert Meeting – UNCRD-KOBE-2007
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