Parametric modeling and seismic analysis of RC...

Parametric modeling and seismic analysis of RC structure based on secondary

development in ABAQUS

Reporter: Qiang Wang Shenyang Jianzhu University, China

December 9, 2016

Topic source: 1. National Natural Science Foundation (51178279) 2. Science and Technology Projects in Shenyang (F16-175-9-00)

ØPresent situationu Research on nonlinear response and collapse damage of structures

under earthquake is an important subject in structural engineering.

u Seismic nonlinear and collapse analysis of RC structures can be

implemented by DEM or FEM.

u FEM is more widely used in numerical simulation.

u ABAQUS is a general FEM software, which is well known for its

ability of solving nonlinear problems.

u However, there exist many difficulties when nonlinear and collapse

analysis of RC structures is simulated based on ABAQUS.

Introduction

ØTopic ideasu In order to improve the ability of nonlinear analysis of ABAQUS,

several uniaxial const itut ive models for concrete and

reinforcement are developed through UMAT/VUMAT interfaces.

u Fracture criteria based on material strain are studied to realize

the fracture simulation of beam element.

u Parametric modeling in ABAQUS is studied for RC structures.

u The seismic response and collapse process of RC structures are

numerically simulated.

Introduction

Main contents

1 • Parametric modeling of RC structure

2 • Development of material subroutine

3• Nonlinear analysis

4 • Collapse process analysis

u It is very tedious and time-consuming to directly build the

model of RC structure in ABAQUS. It is worthy of transforming

the result of structural design into ABAQUS.

u Several transforming procedures have been developed from

SAP2000&MIDAS&YJK to ABAQUS. In these procedures,

structural models are converted to INP files in ABAQUS, so it

is difficult to modify or expand the structure model in

ABAQUS.

u PKPM is the main structural design software in China, but

absent of a direct transforming procedure to ABAQUS.

u Data loss easily occurs when a transformation from PKPM to

SAP2000/MIDAS, then to ABAQUS.

（1） Parametric modeling

（1） Parametric modeling

u Python is used as scripting language to manipulate ABAQUS kernel.

u Geometry layout information of nodes and components in

PKPM/PMSAP are extracted, described in IGES format and then

imported into ABAQUS.

u Other information of structure, such as material, section, rebar,

load and boundary conditions is automatically extracted from

PKPM/PMSAP, and then parametrically complemented in ABAQUS

/CAE.

u Meshing, checking, modifying, re-meshing and expanding the

structural model are carried out in ABAQUS / CAE.

ØMain flow

Ø Transformation of structural layout information

（1） Parametric modeling

Extracting the geometry information

of nodes and components from

PMSAP

Writing an IGES file and importing into

ABAQUS

Partitioning the shear walls and cutting hole in ABAQUS/CAE

Ø Transformation of material

（1） Parametric modeling

Materials in PMSAP Materials in ABAQUS

Ø Transformation of section and rebar

（1） Parametric modeling

u Equivalent section and reinforcement for RC column

Section steelEquivalent rebarConcrete

u Equivalent section and rebar for RC beam

Concrete Equivalent rebar

u Horizontal rebars and vertical rebars of the shear walls are

viewed as rebar layers

（1） Parametric modeling

Concrete vertical rebars layer horizontal rebars layer

Ø Transformation of Boundary Conditions

（1） Parametric modeling

Boundary in PMSAP Boundary in ABAQUS

Ø Transformation of loads and masses

（1） Parametric modeling

Load types in PMSAP Load in ABAQUS

Equivalent to even distributed load

uLoad

u Dead loads and live loads are respectively converted to masses.

u In order to reduce the calculation work, slabs in the rigid-slab region can be omitted in the structural model.

u Loads and masses of the omitted

s l a b s a re t r a n s f e r r e d t o t h e i r

circumjacent beams. u In-plane translational DOFs and

around-normal rotational DOFs of th e i r c i r c u m j a c e n t b e a m s a r e coupling constrained.

（1） Parametric modeling

ØTransformation of rigid slabs

ØConstruction simulation uAccording to the construction order information of PMSAP,

the corresponding analysis steps are created in ABAQUS.u In each steps, birth and death of elements are used to

simulate the state of the accomplished structure.

（1） Parametric modeling

Ø Mesh

uThe built-in mesh function of ABAQUS is used to mesh

the model.

uFor the more complex model, the local region of the

structural model can be manually re-meshed in

ABAQUS/CAE to ensure the mesh quality.

uThe CAE model can be exported to HyperMesh to gain

the expected mesh.

（1） Parametric modeling

（1） Parametric modeling

Comparison of different mesh sizes

ØVerification of transformationuExample 1: frame structure

（1） Parametric modeling

Comparison of the PMSAP and ABAQUS models

• Results of modal analysis

（1） Parametric modeling

PMSAP PMSAPPMSAPABAQUS ABAQUS ABAQUS

1st vibration mode 3rd vibration mode2nd vibration mode

• Comparison of masses and periods

（1） Parametric modeling

uExample 2: frame-shear wall structure

（1） Parametric modeling

Comparison of the PMSAP and ABAQUS models

• Result of modal analysis

（1） Parametric modeling

PMSAP PMSAPPMSAPABAQUS ABAQUS ABAQUS

1st vibration mode 2nd vibration mode 3rd vibration mode

• Comparison of masses and periods

（1） Parametric modeling

Ø Interface of the transforming program(PA-TRANS)

（1） Parametric modeling

（1） Parametric modeling

ØThe built-in concrete and steel constitutive model of ABAQUS

(2)Development of material subroutines

Concrete damage plastic model of ABAQUS(CDP)

Kinematic hardening model of ABAQUS(SPR1)

This model is insufficiently considered for Bauschinger effect

This model can not be used for beam elements in space.

ØConcrete uniaxial constitutive model adopted in the Secondary Development

(2)Development of material subroutines

Concrete uniaxial constitutive model (UCR1)

(2)Development of material subroutines

a. skeleton curve b. unloading and reloading rules

Steel uniaxial constitutive model II (USR2)

Steel uniaxial constitutive model I (USR1)

ØSteel uniaxial constitutive model adopted in the secondary development

uBased on ABAQUS UMAT/VUMAT interfaces and the mater ia l const i tut ive models , s ix user mater ia l subroutines are developed.u The subroutines in UMAT are used for ABAQUS/Standard

solver, and mainly for structural static analysis.

u The subroutines in VUMAT are used for ABAQUS/Explicit

solver, and mainly for structure dynamic analysis.

u IMPORT method is used to transmit the data between them.

(2)Development of material subroutines

ØProfiles of the specimens

（2.1）Example verification

The experiment was performed by Prof. Kazuhiko Kawashima.

Specimennumber

concrete strength

MPa

rebar elastic modulus MPa

Stirrup strength

MPa

Longitudinal rebar strength

MPa

TP74 29.66 2.1*105 321 357

TP77 31.31 2.1*105 321 357

ØUniaxial lateral loading specimen TP74

(2.2)Hysteretic loading analysis of column members

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

شة؛/ط

kN

mm/ئز«خ

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载

/kN

位移/mm

Testing hysteretic curve Calculated curve with UCR1 and SPR1

(2.2)Hysteretic loading analysis of column members

Calculated curve with UCR1 and USR2

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载

/kN

位移/mm

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载/kN

位移/mm

Calculated curve with UCR1 and USR1

Calculated results with USR1 and USR2 more agree with the testing result.

ØBiaxial lateral loading specimen TP77

(2.2)Hysteretic loading analysis of column members

Testing hysteretic curve Calculated curve with UCR1 and SPR1

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载/k

N

位移/mm

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载

/kN

位移/mm

u X direction

(2.2)Hysteretic loading analysis of column members

-60 -40 -20 0 20 40 60

-100

-50

0

50

100

150

荷载

/kN

位移/mm

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载

/kN

位移/mm

Calculated curve with UCR1 and USR1 Calculated curve with UCR1 and USR2

Calculated result with USR1 and USR2 is also closer to the testing result .

(2.2)Hysteretic loading analysis of column members

-60 -40 -20 0 20 40 60

-100

-50

0

50

100

150

荷载/kN

位移/mm

-60 -40 -20 0 20 40 60-150

-100

-50

0

50

100

150

荷载/kN

位移/mm

u Y direction

Testing hysteretic curve Calculated curve with UCR1 and SPR1

(2.2)Hysteretic loading analysis of column members

-60 -40 -20 0 20 40 60

-100

-50

0

50

100

荷载/kN

位移/mm

-60 -40 -20 0 20 40 60

-100

-50

0

50

100

荷载

/kN

位移/mm

Calculated curve with UCR1 and USR1 Calculated curve with UCR1 and USR2

Calculated result with USR1 and USR2 is also closer to the testing result .

ØDynamic nonlinear analysis of frame structure under earthquake

（3）Nonlinear seismic analysis of structures

PMSAP model Transformed Model in ABAQUS

u Earthquake wave

（3）Nonlinear seismic analysis of structures

Acceleration peak value of the wave is adjusted to 510gal, and inputted in X direction.

u Top displacement time history

（3）Nonlinear seismic analysis of structures

0 2 4 6 8 10

-0.2

-0.1

0.0

0.1

0.2

位移(m)

时 间(s)

节点5位移时 程 地震波 时 程

加速度(

cm/s2 )

-400

-200

0

200

400

600

u inter-story displacement angle

（3）Nonlinear seismic analysis of structures

0.000 0.001 0.002 0.003 0.0040

2

4

6

8

10

12

楼层

层间位移角

Inter-story displacement angle

u Plastic distribution

（3）Nonlinear seismic analysis of structures

Plastic hinges primarily occur at the end of the beam end and the bottom column.

Ø Frame-Core Wall Structure under Earthquake

（3）Nonlinear seismic analysis of structures

PMSAP Model Transformed Model in ABAQUS

u Earthquake wave

（3）Nonlinear seismic analysis of structures

Acceleration peak value is 400gal, and inputted in X direction.

u Top displacement time history

（3）Nonlinear seismic analysis of structures

0 5 10 15 20-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

位移

m

时 间s

Midas Abaqus

Top displacement time history comparison between ABAQUS and Midas

Ø Failure criterion When the tensile（compressive ） strain of a fiber in the element section reaches its limit strain value, this fiber will be killed. it means that material in a certain range of element section is failure . When all fibers of the element are failure, the element will be killed, and it can not be recovered. Beam/column component is broken into segments.u Failure criterion of rebar

u Failure criterion of concrete Concrete is considered as fracture, if ε > εcu. εcu =0.05 .

(4)Collapse analysis

Rebar is considered as fracture, if ε > εsu (tensile) or ε < - εsu (compresive) . εsu =0.15 .

Ø Simulation of the failure process of RC column (TP74)

(4)Collapse analysis

Ex.1 monotonic axial loading Ex.2 axial loading and uniaxial lateral cyclic loading

Specimen loading diagram

Ø Example 1: specimen TP74 with monotonic axial displacement loading

(4)Collapse analysis

Curve of Vertical reaction force-displacement

OA segment, The concrete and the reinforced

common pressure rise stage, at the A point of

the concrete to achieve the peak compressive

strength.

AB segment, Concrete and reinforced common

pressure drop stage, at the B point of the

concrete was crushed.

BC segment, Reinforced by the elastic stage

alone, C point for the steel yield 。

BC segment, The steel bar alone yield pressure

stage, the final point of reinforcement at the D

was crushed, thus reinforced concrete column

members completely destroyed.

u Failure of material

(4)Collapse analysis

Stress-strain curve of rebar fibers

With the increase of displacement loaded on the column top, the compressive strain

of reinforced concrete and concrete are gradually increased, and the failure of the member

is occurred after reaching the respective limit of ultimate compression strain

Stress-Strain curve of concrete fibers

uRendering of failure process

(4)Collapse analysis

（a） initial Loading （b） concrete damage （c） Reinforcement damage（d）Movement of residual component after damage

The results are in accordance with the constitutive relations of reinforced concrete and concrete and the failure criterion.

Ø Examples 2: specimen TP74 with the constant axial load and the lateral low cyclic load

(4)Collapse analysis

Hysteresis curves of with/without the failure criterion

When the loading amplitude

i s l a r g e r t h a n 2 2 0 m m , t h e

hysteresis loops are completely

"lying down" and flattened, and

the energy dissipation capacity of

t h e c o m p o n e n t s h a s b e e n

reduced to a very low level due to

the failure of most of the fibers in

the calculation results considering

the failure criterion.

The hysteresis curve without

the failure criterion is still fat.

(4)Collapse analysis

（a） Nonlinear stage （b）Protective layer of concrete fall off （c）Movement of residual component after fracture of the specimen

uRendering of failure process

ØCollapse process of frame structure

(4) Collapse analysis

Collapse

Ø The parametric modeling software(PA-TRANS) can efficiently transform the model of PMSAP into ABAQUS.

Ø The developed constitutive models of concrete and rebar can reasonably describe the nonlinear performance of RC columns.

Ø The limit strain failure criterion can describe the fracture of component , and satisfy with the needs of the collapse process of RC structure .

(5) Conclusion

Thanks for your attention!

(5) Conclusion