1

Evaluation of Seismic
Resistance of Buildings

Taiki SAITO
Chief Research Engineer,International Institute of Seismology and Earthquake Engineering (IISEE),

Building Research Institute (BRI)

2

Seismic Resistance of Building
Seismic Resistance = Potential Energy
C (Capacity)

F (Flexibility)

C ((Capacity)py)EnergyCapacity
CCurveCollapse

F (Flexibility)
C (Capacity)

F (Flexibility)

C (Capacity)
EnergyCollapse
F (Flexibility)

3

Seismic Index “Is”
I = (Φ × C×F ) × SD × TIsΦSDT:factor for number of story: factor for shape of building: factor for age of building“DesignDesign guideline for
Seismic Evaluation for RC
structures (2001)”
Increase C?

C (Capacity)( py)

Is＞0.6
C ((Capacity)py)

F (Flexibility)((Safe))I ＜0 6
Is＜0.6

Increase F?

(Danger)F (Flexibility)

Capacity Curve

4

Strategy for Seismic Rehabilitation
C (Capacity)
(a)
(b)
(c)
F (Flexibility)

Evaluation of Is

Is > 0.606?

NO(a) Increase C(b) Increase C & F

YES
Pass

(c) Increase F5Rehabilitation Techniques(1. Conventional method)C (Capacity)

Increase C

Increase C&F

Is＞0 6
Is＞0.6Is＜0.6(Safe)

Increase F(D(Danger))

Original

Capacity Curve

F (Flexibility)(Photo from Dr. Fukuyama, BRI)

6

Example (Increase F)
Rehabilitation by Carbon Fiber Sheetno noise, no dust, no disturbance(Photo from Dr. Fukuyama, BRI)

Rehabilitation Techniques((2. Damperp device))

7

Oil damper

DamperC (Capacity)

OILES
http://www.oiles.co.jp

DamperH
Honey-comb
bddamper(Safe)(Danger)

Energy dissipation bydamper device

http://www.kajima.co.jp

Manyy other devices

Original

Capacity Curve

KAJIMAF (Flexibility)

8

Example (Damper)

Damper wall
Steel frame

3F-8F
3F
8F Dampers
B2F-2F no retrofit（社）建築・設備維持保全推進協会パンフレットより抜粋

9Rehabilitation Techniques(3. Seismic isolation)
C (Capacity)

Laminated Rubber bearing

Lead damper(Safe)

Steel damper
Original

Capacity Curvey)
F ((Flexibility)

10

Capacity curve and performance
Damagegrade III

Damagegrade II

Damagegrade I

Capacity Curve

C (Capacity)

F (Flexibility)

Re

RHmax

(Heavy Damagee)

Elastic Limit(Modeerate Dammage)Ulti t Limit
Ultimate
Li it(Lighht Damagge)

REESISTA
ANCE

Maximum Resistance

RuDEFORMATION

Collapse

×R coll11

Capacity curve of plain masonry wallf t : tension strength of brickσ 0 : compression strength of brickH max = Awftbσ0ft+1H max
H d max
H cr

H d max = Csd H max
H cr = Ccr H max
Ked cr =H cr
kedd H max =H max
0.51Ked max =H d max
0.16 Ke

12

Capacity curve of confined masonry wallf y : strength of rebar
f c : compression strength
h off concrete
H max =f t AwN ⎞2⎛2
[1 + [1 + C I ⎜⎜1 + w ⎟⎟] + n 0.896 d rv f c f yCI b⎝ Aw f t ⎠H max
H d max
H cr

H d max = Csd H max
H cr = Ccr H max
Ked cr =H cr
kedd H max =H max
0.43Ked max =H d max
0.02 Ke13Example

353 KN

222 KN247 KN

262 MPa184 MPa

210 MPaR = 1/1400 R = 1/500 R = 1/200
R = 1/1300 R = 1/350

dR = 1/25

STERA 3D software

14• Seismic analysis ofreinforced concrete +masonry buildings– 3D elastic modal analysis,– 3D nonlinear static push-overand cyclic analysis,– 3D nonlinear earthquake
response analysis.
l i• Visual interface– Visual interface to createbuilding models and show theresults easily and rapidly.

• Free software– STERA 3D is distributed forfree for the use of researchand educational purpose.

• Free download from Web– Search “STERA3D”

Element Models• Beam• Column
C l• Wall• External Springs• BaseB
IIsolationl ti• Dampersa pe s• MasonryBeam

Beam
Nonlinear bending spring

Nonlinear shear spring

Modified Takeda Model

Origin Oriented ModelColumnColumn

Multi spring (MS) Model

Nonlinear Bending Springs

WallWallMulti spring (MS) Model

Nonlinear Bending Springs

External SpringBase Isolation Device

Multi shear spring (MSS) ModelDamper Device
Force – Deformation relationship

Hysteresis damper
FForce– Velocity
V l i relationshipl ihi

Oil damper

Viscous damper

Masonry Wall
N li
Nonlinear
ShShear SSpringi

Poly-linear Slip Model

http://iisee kenken go jp/net/saito/stera3d/index html
http://iisee.kenken.go.jp/net/saito/stera3d/index.html

Other software for seismic analysis27

Frame analysis (STERA 3D Software)
FEM (Finite Element Model) analysis
DEM ((Discrete Element Model)) analysisy((STERA Briq Software))
FEM analysis

DEM analysis

Stress distribution

Collapse analysis

Conclusions• Seismic resistance = potential energy• Seismic rehabilitation strategy using capacity curve– Increase C,
C F,
F or C&F– Using damper devices– Seismic
S i i IIsolationl ti• Capacity curve for masonry– Plain masonry < Confined masonry• Tools for seismic analysis– STERA3D– DEM software (SERABriq)(q)28