Effect of Modeling Parameters on Collapse Behavior of RC Building

Adolfo B. Matamoros, Anil Suwal, and Andres Lepage

16th U.S.-Japan-New Zealand Workshop on the Improvement of Structural Engineering and ResiliencyNara, Japan, 27-29 June 2016

Rehabilitation Objective Modeling Parameters

Acceptance Criteria

Maximum ConsideredEarthquake

474 yrs

225 yrs

72 yrs

2475 yrs

ASCE-41Standard

FEMA P695 MethodologyEquivalent safety against collapse for buildings with different seismic force resisting systems

Collapse Safety Margin

Global InstabilityLocal Instability

Median Collapse: One-half of the structures have some form of collapse

Collapse Margin Ratio, CMR =SA Median collapse-level ground motions

SA of MCE ground motions

NEHRP: Structure should have a low probability of collapse for MCE (1.5 times the design level earthquake)

Design Criteria for Building Codes (i.e. R, Cd, and Ω0 seismic performance factors)

CMR is established through Incremental Dynamic Analysis

0.00

0.50

1.00

1.50

2.00

2.50

3.00

0 0.01 0.02 0.03 0.04 0.05

Inte

nsity

Mea

sure

Drift Ratio

1st Story

2nd Story

3rd Story

4th Story

5th Story

6th Story

-200

-100

0

100

200

0 5 10 15 20

Building Description• Seven-story RC Building in Van Nuys, CA• Designed in 1965 and constructed in 1966• Exterior moment-resisting frames• Interior gravity load flat slab system• Strong motion records from:

– 1971 San Fernando – 1987 Whittier – 1990 Upland– 1992 Sierra Madre– 1994 Northridge

• Light structural damage during the 1971 San Fernando Earthquake, severe column damage during the 1995 Northridge earthquake.

Building Plan40 x 56 cm spandrel beam around perimeter (40 x75 cm first floor)

35 x 50 cmext. columns

45 cm square int. columns

19.1 m

45.7 m

interior frame

exterior frame

N

S

Lumped Plasticity Model for Frame Structure

Moment rotation relationship for nonlinear rotational spring of second story column of RC Building

Rotation

Mom

ent

Two Node Joint Elastic ElementJoint Offset

Evaluation Ground Motion• 1994 Northridge record SE Corner E-W• PGA 0.45 g

IM 1.0

IM 2.72 IM 2.73

Collapse Simulation Results EW Direction

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

0

0.5

1

1.5

2

2.5

3

1st Story

2nd story

3rd story

4th story

5th story

6th story

7th story

Average

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

0

0.5

1

1.5

2

2.5

3

1st Story

2nd story

3rd story

4th story

5th story

6th story

7th story

Average

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

0

0.5

1

1.5

2

2.5

3

1st Story

2nd story

3rd story

4th story

5th story

6th story

7th story

Average

Drift Ratio

Inte

nsity

Mea

sure

0

500

1000

1500

2000

2500

0 0.02 0.04 0.06 0.08

Mom

ent (

kip

in.)

Rotation (radians)

ASCE 41-13 column ACI 369 column

0200400600800

1000120014001600

0 0.02 0.04 0.06 0.08

Mom

ent (

kip

in.)

Rotation (radians)

ASCE 41-13 beam New beam model

0 0.5 1 1.5 2 2.5

Intensity Measure

0

0.2

0.4

0.6

0.8

1

Perc

enta

ge o

f Col

umns

Exc

eedi

ng

Yield

Capping

Post-Capping

0 0.5 1 1.5 2 2.5

Intensity Measure

0

0.2

0.4

0.6

0.8

1

Perc

enta

ge o

f Col

umns

Exc

eedi

ng

Yield

CappingPost-Capping

0 0.5 1 1.5 2 2.5

Intensity Measure

0

0.2

0.4

0.6

0.8

1

Perc

enta

ge o

f Bea

ms

Exce

edin

g

Yield

CappingPost-Capping

Intensity Measure

0 0.5 1 1.5 2 2.5

Perc

enta

ge o

f Spr

ings

Exc

eedi

ng

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Yield

CappingPost-Capping

Two Node Joint Elastic ElementJoint Offset

Two Node Joint Elastic ElementJoint Offset

0

1000

2000

3000

0 0.02 0.04 0.06 0.08

ASCE 41-13columnACI 369 column

ASCE 41-13 ACI 369

Conclusions• Changes in modeling parameters for beams and columns affected

the distribution of damage of the case-study building. • The intensity measure corresponding to lateral instability for the

model with ASCE 41-13 modeling parameters was 1.63 (0.77 g), whereas the maximum intensity measure for the model with ACI 369 modeling parameters was 2.71 (1.27 g).

• The effect of beam modeling parameters on the intensity measure corresponding to lateral instability was not significant for the case-study building, although the maximum story drift ratios before lateral instability did increase by approximately 1%.

• While the intensity corresponding to lateral instability increased significantly by adopting modeling parameters representative of the mean response of component tests, the level of damage expected to occur in gravity-load frames increased significantly as well.