Seismic behavior and modeling of gravity-slab-framing system in concrete core wall high-rise buildings

Tony Yang, Ph.D. Assistant Professor, University of British Columbia

•  116 Completed (>75m ~= 240 ft.) •  43 Planned •  20 Demolished •  5 under construction •  13 Never built

Source: http://www.emporis.com/

High-rise buildings in San Francisco

(On hold….)

Concrete core shear wall buildings

MKA

San Francisco, Rincon Center

MKA

Concrete core shear wall buildings

Core shear wall

Link beam PT slab

Concrete core shear wall buildings

http://activerain.com

Gravity column Core wall PT slab

Structural design

Code design:

•  Design the core wall without the gravity system.

•  Design the gravity system without the seismic effect.

•  Gravity system need to be design for the ductility…

Questions: Is it safe …?

Is it all?

MKA

PT slab column wall gravity system

UCB

PT slab column wall gravity system

PT slab column wall gravity system

PT slab column wall gravity system

PT slab column wall gravity system

m1 m2

w

m2

Slab (BC element with lumped plastic hinges).

Wall (BC element)

Column (BC element)

F1, D1 (master) F1, D1 (slaved)

PT slab column wall gravity system

-0.1 -0.05 0 0.05 -30

-20

-10

0

10

20

30

40

Drift ratio [-]

Forc

e [k

ips]

Experimental Test Analytical Simulation

Floo

r N

umbe

r Lateral system

Gravity-only system

Nonlinear analytical model

Fiber section

UCLA – J. Wallace

Modeling the concrete coupling beams

M,θ M,θ

Analytical Experimental

M

θ

Perform3D – gravity framing systems

A A

Plane A-A view Lump plastic hinge model:

Nonlinear dynamic analyses  3D bi-directional shaking.  Ground motion are selected based on:

  Database: PEER NGA database.   Magnitude (Mw): 6.5 - 8.   Distance (R): 10 km (0 - 20 km).   Useable periods: > 8 sec.

Selection of the ground motions

0 1 2 3 4 5 6 7 8 9 10 0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Period [sec]

Sa [g

] CW48WGF (T1 = 4.3 sec)

CapCPM (SF = 2.1) CapFOR (SF = 4.1) CapPET (SF = 2.3) DuzDZC (SF = 1.2) GazGAZ (SF = 1.8) KobAMA (SF = 2.1) KobFKS (SF = 2.5) KobPRI (SF = 1.4) LomLGP (SF = 1.1) LomSTG (SF = 2.5) LomWVC (SF = 2.1) Target spectrum (MCE - SF) Mean (MCE - SF)

0.2 T1 to 1.5 T1

Variation of EDP vs. story height

Variation of EDP vs. story height

X S

-9 -8 -7 -6 -5 -4 -3 -2 -1 0 B5

L1

L6

L11

L16

L21

L26

L31

L36

L41

axialForceGCS [kips]

Floo

r num

ber [

-]

x 1e3

GL + GM GL + PushoverX GL + mean GM GL + mean GM ± std GM

CW48WGF

Average = 96% of PushoverX Max = 99% of PushoverX Min = 90% of PushoverX

Maximum un-factored axial forces

-12 -10 -8 -6 -4 -2 0 B5

L1

L6

L11

L16

L21

L26

L31

L36

L41

axialForceGCS [kips]

Floo

r num

ber [

-]

DL

LL LLred

EQ

-14

x 10 3

Maximum factored axial forces

-2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 x 10

4 B5

L1

L6

L11

L16

L21

L26

L31

L36

L41

axialForceGCS [kips]

Floo

r num

ber [

-]

1.4*DL 1.2*DL+1.6*LLred 1.0*DL+0.25*LL+EQ

90% of design load.

Effect of modeling the gravity system   Change in structural periods and stiffness

T1 T2 T3 CW48NGF 4.72 sec 4.10 sec 2.66 sec CW48WGF 4.27 sec 3.86 sec 2.65 sec

% change in stiffness 22% 13% 1%

Effect of modeling the gravity system

0 50 100 B5

L1

L6

L11

L16

L21

L26

L31

L36

L41

Floo

r num

ber [

-]

Story Drift – H1 [in.]

0 1e4 2e4 3e4 B5

L1

L6

L11

L16

L21

L26

L31

L36

L41

Core Shear - H1 [kips]

0 1 2 3 x10 7 B5

L1

L6

L11

L16

L21

L26

L31

L36

L41

Core Moment - H2[kip-in.]

CW48WGF CW48NGF

1.5% of building height

Summary and conclusions  Slab-wall-column framing is a prevalent design.  Experimental tests and analytical simulations

have been conducted to study the seismic effect.  Effect on structural responses:  Stiffness:  Core wall:  Gravity column:

(10% ~ 25% ). Modest change. Insignificant.

a) Potential significance.

b) Simplified plastic analysis.

Questions and suggestions? Thank you for your attention!

Contact information:

Tony Yang: yangtony2004@gmail.com

http://peer.berkeley.edu/~yang/

PT slab column wall gravity system

Hwang and Moehle (2000) ACI Structural Journal

Beff = 120”

Beff = 80”

Effective slab width:

PT slab column wall gravity system

8” 120”

1.5” 1.5”

#5 A615 Grade 60 steel @ 12” o.c.

fc’ = 6100 psi (@ 17 days)

67

100

Stress [ksi]

Strain [-]

0.08 0.12

E = 2900 ksi

90

A615 Grade 60 steel rebar:

0

Stress [ksi]

Strain [-] 0.002 0.005

Concrete (fc’ = 6100 psi @ 17 days):

0

6.1

PT slab column wall gravity system

Plastic rotation [-]

M1

[kip

-in.]

-0.2 -0.1 0 0.1 0.2 -2

-1

0

1

2

-0.1 -0.05 0 0.05 0.1 -4 -3

-2

-1

0 1

x1e3 x1e3

M2

[kip

-in.]

Plastic rotation [-]

M+,θ+