RESPONSE REDUCTION FACTORS IN DIFFERENT SEISMIC CODES

Transcription

1 in the Euro-Mediterranean Area RESPONSE REDUCTION FACTORS IN DIFFERENT SEISMIC CODES APPLICATION TO THE A SPANISH COMPARISON CASE Alex H. Barbat Juan Carlos Vielma Sergio Oller E. T. S. Ingenieros de Caminos Canales y Puertos Universidad Politécnica de Cataluña, a, Barcelona

2 Response reduction factors ductility in the Euro-Mediterranean Area usually associated with structural ductility Eurocode-8 behavior factors q q = q k 1.5 w factor of prevailing Basic reduction factor failure mode

3 Effect of the behavior factors q in the Euro-Mediterranean Area Sa/g Elastic design spectrum Inelastic design spectrum q EC-8 T(s)

4 EC-8 in the Euro-Mediterranean Area EUROCODES R Regular 5.94 Response reduction factors (behaviour factors) Framed reinforced concrete buildings One storey building Plan irregularity Without quality control Irregularity is penalized 4.13 Elevation irregularity 4.95 Elevation and plan irregularity Multistorey one bay building 6.48 ductility class high DCH- Multistorey multibay building Redundancy benefits are recognized

5 in the Euro-Mediterranean Area EUROCODES R One storey building 3.96 Response reduction factors (behaviour factors) Framed reinforced concrete buildings ductility class medium DCM- EC-8 Multistorey one bay building Multistorey multibay building

6 Response reduction factors Spanish seismic code NCSE-2 in the Euro-Mediterranean Area R Framed buildings without infill walls 3.66 High ductility Medium ductility 2.74 Low ductility 1.83 Framed buildings with infill walls 4 High ductility 3 Medium ductility 2 Low ductility Shear walled buildings 2.15 Low ductility

7 EUROCODES Response reduction factors comparison in the Euro-Mediterranean Area EC-8, regular buildings EC-8, irregular buildings NCSE-2 Venezuela 1998 Venezuela 1998 UBC-97 IBC-23 New Zealand 22 Japan 24

8 in the Euro-Mediterranean Area EC-8 NCSE-2 Structural type Moment-resisting framed buildings Framed buildings with wide beams Waffled slabs buildings Moment-resisting framed buildings Framed buildings with wide beams Waffled slabs buildings High μ>4 (*) For intermediate ductility, EC-8 8 requires certain conditions for the beam width yes no no no no no Ductility Intermediate 3 μ 4 yes yes (*) no yes no no Low μ<2 yes yes yes yes yes yes

9 Ductility Strength Stiffness in the Euro-Mediterranean Area NCSE-2 EC-8 F k Capacity curve μ R F F Δ Δ Δ

10 .6 EUROCODES Base in the shear Euro-Mediterranean coefficient (V/W) Area Desplome (%) Design base shear Interstorey drift (%)

11 .61 EUROCODES Base in the shear Euro-Mediterranean coefficient Damage (V/W) Area D W p = 1 W Δ y p μ = Δ Δ u y Desplome (%) = 4,2,8 Design base shear NCSE-2: μ=4 actual potential energy = 5,25 fictious, elastic potential energy Interstorey drift (%) Δ u

12 EUROCODES Desplome (%) Coeficiente de cortante en la base (V/W) Base in the shear Euro-Mediterranean coefficient (V/W) Area Damage.25 NCSE-2: μ=2 Design base shear μ = Δ Δ u y = 1,92 1,86 = 1,57 Interstorey drift (%) Δ y Δ u

13 ,6 1.75,4.5,2 EUROCODES Coeficiente de cortante en la base (V/W) Base in the shear Euro-Mediterranean coefficient (V/W) Area Damage.25,3,6,9 1,2 1,5 1,8 2,1 2,4 μ NCSE-2: μ=2 = Δ Δ u y = 2,33 1,488 = Desplome (%) 1,55 Design base shear μ=2.33/1.488=1.55 Δy Δu Interstorey drift (%) Δ y Δ u

14 Comparisons in the Euro-Mediterranean Area Shear base coefficient (V/W) Waffled slabs building Framed building with wide beams Interstorey drift (%) Moment-resisting frame

15 Waffled slabs buildings Comparisons in the Euro-Mediterranean Area Shear base coefficient (V/W) B 5 W B 5 WD B 4 W B 4 WD Interstorey drift (%)

16 Waffled slabs buildings Comparisons in the Euro-Mediterranean Area Shear base coefficient (V/W) B 5 WD B 5 WD improved confinement Interstorey drift (%)

17 in the Euro-Mediterranean Area EUROCODES EC-8 Slabs should have enough stiffness to transmit the seismic forces uniformly to the vertical resisting members

18 in the Euro-Mediterranean Area The mass and stiffness uniformity has to be maintained in plant and elevation to avoid torsion and stress or ductility concentrations EC-8 A high degree of structural redundancy is recommended to assure moment Workshop redistribution November 26, Varese, Italy

19 EC-8 Slabs at different levels can be the origin of short columns in the Euro-Mediterranean Area

20 in the Euro-Mediterranean Area EUROCODES (1) All lateral load resisting systems, like cores, structural walls or frames, run without interruption from their foundations to the top of the building EC-8 Structures should allow a clear transmission of loads from the roof system to the foundation system to Workshop the foundation November 26, Varese, Italy

21 in the Euro-Mediterranean Area EUROCODES EC For a primary seismic beam supporting columns discontinued below the beam, the following rules apply: a) There shall be no eccentricity of the column axis relative to that of the beam; b) The beam shall be supported by -at least- two direct supports, such as walls or columns.