Tesi angela saviotti

a. a. 2011-2012

Faculty of Civil and Industrial Engineering
Department of Structural and Geotechnical Engineering

“FINITE ELEMENT ANALYSIS OF INNOVATIVE SOLUTIONS OF
PRECAST CONCRETE BEAM-COLUMN DUCTILE CONNECTIONS”

Advisor: Candidate:
Prof. Ing. Franco Bontempi Angela Saviotti

Co-advisor:
Ing. Pierluigi Olmati

“Finite element analysis of innovative solutions of precast concrete beam-column
ductile connections”
Treated models
2D MODEL:
-Model “A” with mortar stratum for beam-column connection;
-Model “B” without mortar stratum for beam-column connection.

2D “A” 2D “B”

•3D MODEL:
-Model “A” with mortar stratum for beam-column connection;
-Model “B” without mortar stratum for beam-column connection.

3D “A” 3D “B”

Department of Structural and Geotechnical Engineering 2/25

“Finite element analysis of innovative solutions of precast concrete beam-column
ductile connections”

•FEM analytical program: DIANA V. 9.3

•Geometry and Mesh of the structure, to assign boundary

conditions and loads: Midas FX+ for DIANA

•Non-linear mechanisms :

-Cracking of the concrete

-Yielding of the steel.
CONCRETE – Total Strain Crack Model STEEL – Von Mises
Tensile Behavior Compressive Behavior


Angela Saviotti - Finite element analysis of innovative solutions of precast concrete beam-column ductile connections
STRUCTURE

Column
H=4700 mm
Beam
L=3770 mm



BOUNDARY CONDITIONS AND LOADS 2D

Beam-Column
FIRST LOAD CONDITION joint failure after
SEISMIC SITUATION earthquake -
http://strutturisti.
wordpress.com/

SECOND LOAD CONDITION
ACCIDENTAL SITUATION

The Bombing of the Federal
Building in Oklahoma City -
http://911research.wtc7.net/ind
ex.html



MODEL “A” MODEL “B”


MODEL 2D
MESH
Steel Plates Beam and Column:
Concrete, Mortar, Rubber and Steel Plates Concrete C40/50

MODEL “A”

Rubber pad Connection
Stratum:
Mortar

MODEL “B” Four-node quadrilateral plane
stress elements (Q8MEM)
Reinforcing Steel Zoom of Beam-Column joint

Two-node straight truss
elements (L2 TRU) Three-node triangle plane stress
elements (T6MEM)



FIRST LOAD CONDITION : Applied Horizontal Force at the top of the column 2D
NON LINEAR ANALYSIS
STEEL CONCRETE
Compressive Behavior Tensile Behavior
Tension Softening
Linear Elasticity Ideal Plasticity Linear Elasticity Ideal Linear Elasticity curve based on
fracture energy

A1 X X X
B1 X X X
A2.1 X X X
B2.1 X X X
A3.1 X X X
B3.1 X X X
A4.4 X X X
B4.4 X X X



NON LINEAR ANALYSIS

STEEL CONCRETE
Compressive Behavior Tensile Behavior
Tension Softening
Linear Elasticity Ideal Plasticity Linear Elasticity Ideal Linear Elasticity curve based on
fracture energy

A1 X X X
B1 X X X
A2.1 X X X
B2.1 X X X
A3.1 X X X
B3.1 X X X
A4.4 X X X
B4.4 X X X



SECOND LOAD CONDITION : Imposed vertical displacement at the top of the column 2D
NON LINEAR ANALYSIS – CYCLIC ANALYSIS
MODEL “A”
Deformed
configuration developed
by the structure at STEP
n. 25 imposed maximum
displacement δ=80 mm.



SECOND LOAD CONDITION : Imposed vertical displacement at the top of the column 2D
NON LINEAR ANALYSIS – CYCLIC ANALYSIS
MODEL “A”
Step 25

Step 50, imposed Step 110
Step 25, imposed
displacement δ=80 displacement δ=0
mm mm

Step 80 Step 50

Step 80, imposed Step 110, imposed
displacement δ= - 80 mm displacement δ=0 mm

STRESS on reinforcing steel
CRACKING STATUS
Step 25
Step 1

Step 25 σmax=450 .0 N/mmq Step 50 σmin = - 450 .0 N/mmq

Step 50 Step 80

Step 80 σmin= - 450 .0 N/mmq Step 110 σmin= - 203.25 N/mmq



12/25

MODEL 3D
MESH
Concrete, Mortar, Rubber and Steel Plates Four-node, three-side iso-
parametric solid pyramid
elements (TE12L)

158634 solid elements
9106 bar elements
31639 nodes
Total of around 142941 degree of Two-node straight truss
freedom elements (L2 TRU)

Two-node, two-
dimensional class-II
beam element (L7BEN)


FIRST LOAD CONDITION: Applied Horizontal Force of 600 kN at the top of the column

3D
LINEAR ANALYSIS

Displacements
mm mm


FIRST LOAD c
CONDITION: Applied Horizontal Force at the top of the column

LINEAR ANALYSIS

Stress on reinforcing steel


3D
FIRST LOAD CONDITION : Applied Horizontal Force at the top of the column
NON LINEAR ANALYSIS


3D
FIRST LOAD CONDITION : Applied Horizontal Force at the top of the column
NON LINEAR ANALYSIS


mm
mm

Deformed configuration developed by the structure at Deformed configuration developed by the structure at
STEP 20 – Fmax= 390.2 kN, δmax=88.6 mm. STEP 15 - Fmax= 269.83 kN, δmax=87.27 mm


NON LINEAR ANALYSIS: Stress on Reinforcing Steel

STEP 5 Fmax= 128 kN, STEP 5 Fmax= 128.7 kN,
δmax=5.17 mm δmax=6.97 mm
σmax=108.21 N/mmq σmax=233.0 N/mmq

STEP 10 Fmax= 205 kN,
STEP 10 Fmax= 207 kN, δmax=16.9 mm
δmax=12.75 mm – σmax=365.0 N/mmq
σmax= 206.66 N/mmq

STEP 15 Fmax=270 kN,
δmax=88.56 mm σmax=450.0 N/mmq
σmax=450.0 N/mmq


NON LINEAR ANALYSIS: Stress on Reinforcing Steel

σmax=108.21 N/mmq σmax=233.0 N/mmq

δmax=12.75 mm – σmax=365.0 N/mmq
σmax= 206.66 N/mmq

δmax=88.56 mm σmax=450.0 N/mmq
σmax=450.0 N/mmq


FIRST LOAD CONDITION: Applied Horizontal Force at the top of the column 3D
NON LINEAR ANALYSIS: Cracking Status


δmax=12.75 mm

δmax=88.56 mm


SECOND LOAD CONDITION : Imposed vertical displacement at the top of the column
NON LINEAR ANALYSIS 3D
Deformed Deformed
configuration developed configuration developed by
by the structure at LAST the structure at LAST STEP
STEP imposed imposed displacement
displacement δ=120 mm. δmax=150 mm

Stress–Strain graph of beam-column ductile connection Model “A” Vs
Force-Displacement graph: Model “A” Vs. Model “B” Model “B”


NON LINEAR ANALYSIS: Stress on Reinforcing Steel 3D

STEP 1 Fmax= 143.9 kN,
δmax=10 mm
σmax=196.41 N/mmq

STEP 1 Fmax= 123.6 kN,
δmax=10 mm
σmax=268.1 N/mmq

STEP 5 Fmax= 232.5kN,
δmax=50 mm STEP 5 Fmax= 139.4 kN,
σmax=450.0 N/mmq δmax=50 mm
σmax=348.3N/mmq

STEP 12 Fmax= 223.13 STEP 12 Fmax= 139.95
kN, δmax= 120 mm kN, δmax=120 mm
σmax=450.0 N/mmq σmin=-450.0 N/mmq


3D
NON LINEAR ANALYSIS: Crack Strain

STEP 1 Fmax= 143.9 kN, STEP 1 Fmax= 123.6 kN,
δmax=10 mm δmax=10 mm
εknn=0.00242 % εknn=0.00703 %

STEP 5 Fmax= 232.5kN, STEP 5 Fmax= 139.4 kN,
δmax=50 mm δmax=50 mm
εknn=0.0359 % εknn=0.0548 %

STEP 12 Fmax= 223.13 STEP 12 Fmax= 139.95
kN, δmax= 120 mm kN, δmax=120 mm
εknn=0.224% εknn=0.132 %



• Structural continuity is an important problem.

•DIANA software, modeling the nonlinear behavior of concrete and mortar using total
strain crack model. The reinforcing steel is modeled by a bilinear plasticity model

• The full load capacity of the bars is developed without the failure of the concrete and
the mortar

• The progress of the cracking of the concrete is well reproduced.

• The similarity between the results obtained with two different finite
element programs, the previously mentioned DIANA and ASTER.

• The role of the mortar stratum is weighted

• The introduction of the connectors inside the mass of concrete.

24/25


2D

3D

Faculty of Civil and Industrial Engineering 25/25

Tesi angela saviotti

More Related Content

Viewers also liked

Similar to Tesi angela saviotti

Tesi angela saviotti