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cross-section column
the cross section of the column model consists of confined concrete ( conf )
non-confined concrete ( unc )
has the following characteristics
characteristic rate
sectional shape rectangular
Width 30 cm
height 40 cm
reinforcement at corners 4/16
reinforcement upper and lower cheek Φ/12
lateral sidewall reinforcement 2/12
total reinforcement 4/16+6/12
Figure 6. section column
http://postimg.org/image/3yjmc0263/
Distinguish three different materials
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cross-section beam
The cross beam consists of confined concrete ( conf )
non-confined concrete ( unc )
has the following characteristics
characteristic rate
sectional shape T-shaped plate-girder
effective width 100 cm
slab thickness 15 cm
beam height 60 cm
beam width 25 cm
reinforcement beam down 3/14
reinforcement beam over 2/14
Buccal armature beam Φ10/cheek
armor plate over 6/10
armor plate under 4/10
total reinforcement 5/14+12/10
Figure 7. cross beam. distinguish three different materials.
http://postimg.org/image/liebad51d/
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finite elements
the finite element models used in the building is a three-dimensional non - linear ribbed finite element based on the strength
(3D Inelastic force-based element ) with 4 integration points along with visa fibers.
The number of fibers in each section is 200
this item is used for the simulation of columns and beams.
Figure 8. finite element space, to simulate columns and beams
http://postimg.org/image/48p23wyrb/
4.4 analysis - methodology
performed nonlinear analyzes for each building with the finite element method, taking into consideration effects of nonlinearity of material and geometry.
analyzes are non-linear, static ( pushover ), while charging a triangular distribution
height which corresponds approximately to the first peculiarity of the examined structure
The total number of trainees loads has rate 1kN that the base shear during charging it to a rate 1kN and therefore importune coefficient λ is equal to the base shear (1*λ) for the various phases of the analysis.
value - the objective of the movement is set at 0.18 m
The load is transmitted in 50 steps for both models.
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As a control node set node of higher level of construction ( z=max ) to whom x=0 and y=0, as shown in more detail in Figures
The proposed system causes the exercise of a compressive force in each column where applicable.
The simulation of this phenomenon
been addressed by imposing a compressive strength in columns
considered that the system applies.
5. three-storey reinforced concrete building
5.1 general characteristics of the building.
the test building displays regularity
in plan and height.
general characteristics of the building.
floor height............................................ .......3m
span length x ...............................................5m
span length z ...............................................5m
diaphragm ....... yes on each floor
supports .......... anchors on all nodes with z=0 (ground)
Figure 9. plan three-storey building
http://postimg.org/image/a050s6yg7/
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Figure 10. front face of the three-storey building
http://postimg.org/image/viypllunn/
Figure 11. side view of the three-storey building
http://postimg.org/image/6mws5h4vb/
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Figure 12. perspective view of a three storey building (a)
characterized the control node of the structure
http://postimg.org/image/kqx8rm1gn/
Figure 13. perspective view of a three storey building (b)
characterized the control node of the structure.
http://postimg.org/image/jzxkdmhvb/
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5.2 analytical results
5.2.1 without the application of prestressing.
The following figure shows the diagram
base shear - displacement for node monitoring.
Figure 14. power curve (kN) - displacement (m) without the application of prestressing
http://postimg.org/image/jzxkdmhvb/
the maximum value of the chart is 900.62 kN, illustrated for the displacement of the control node 0.1296 m
5.2.2 compressive load 600 kN to nodes of higher level.
Applied compressive load 600 kN to nodes of higher level due to the prestressing force.
Initial (A) charged with the compressive force the central column.
then (B) the load applied to the four corner columns.
to the end (C) loaded all the 9 columns of the building
The positive trend in each column is ..
600 kN / (0.30 m * 0.40)=5000 kN/m2=5MPa
the ultimate limit state of column
because grief
(Taking into account the safety factor
having a value of 1.5 for concrete),
the tensile strength for concrete C 30 is 30 MPa/1.5=20MPa.
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therefore the positive trend in the columns corresponding to the 5/20 = 25% strain at break,
the ultimate limit state.
A. Compressive load of 600 kN to the central hub of higher level.
The diagram below shows the chart base shear-movement
for the control node.
Figure 15. power curve (kN) - displacement (m) applying compressive load 600 kN at 4 corner nodes of higher level
http://postimg.org/image/50gpcep27/
the maximum value of the diagram without the application of prestressing was
600.62 kN for displacement 0.1296 m
the maximum value of the chart by applying a compression load 600
to the central hub of the upper level is
929.82 kN for displacement 0.1116 m
improving the carrying capacity is
978.77 - 929.82 = 48.95 kN
the percentage improvement in base shear is
48.95 / 900.62 = 5.4%
result
There is a slight improvement in the carrying capacity of the building,
due to the application of the compressive load on the central column of the building.
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B.Compressive load 600 kN at 4 corner nodes of higher level.
The following figure shows the base shear diagram
- Movement on the control node.
Figure 16. power curve - Shift by applying compressive load 600 kN at 4 corner nodes of the upper level
http://postimg.org/image/pakwo6603/
the maximum value of the diagram without the application of prestressing was
900.62 kN for displacement 0.1296 m
the maximum value of the chart by applying a compression load 600 kN at 4
corner nodes of the upper level is.
978.77 kN for displacement 0.1044 m
improvement in carrying capacity is.
978.77 - 900.62 = 78.15 kN
the percentage improvement in base shear is.
218.39 / 900.62 = 8.7%
result
there is a slight improvement in the bearing capacity of the building, through the application of compressive forces in the four corner columns of the building.
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Γ. Compressive load 600 kN on all nodes of higher level.
The following figure shows the diagram base shear - displacement for node control
Figure 17. power curve ( kN ) - displacement ( m )
applying compressive load 600 kN on all nodes of higher level
http://postimg.org/image/i7pfrq2sd/
the maximum value of the chart without applying prestressing was
900.62 kN for displacement 0.1296 m
the maximum value of the chart by applying a compression load 600 kN to all nodes of the upper level is
1,119.01 kN for displacement 0.1008 m
improvement in bearing capacity is 1119.01 - 900.62 = 218.39 kN
The percentage improvement in the maximum base shear is 218.39 / 900.62 = 24.2%
result
observed a significant improvement in the bearing capacity of the building, through the application of compressive forces in all the 9 columns of the building
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5.2.3 compressive load 1,200 kN to nodes of higher level
applied compressive load 1,200 kN to nodes of higher level, ratio of prestressing force.
initially ( A ) charged with the compressive strength the four corner columns
slowly charged and nine columns of the building
applied compressive load 1,200 kN to nodes of higher level due to the prestressing force.
The positive trend in each column is
1200 kN / ( 0.30 m *0.40 m ) = 10,000 kN/m2 =10 MPa
the ultimate limit state of the column due to grief (taking into account the safety factor has a value of 1.5 for concrete)
the tensile strength for concrete C 30 is 30 MPa / 1.5 = 20 MPa
therefore
The positive trend in columns
corresponds to 10/20 = 50% strain at break
A. compressive load 1,200 kN at 4 corner nodes of higher level
The following figure shows the base shear diagram - movement on the control node.
Figure 18. power curve (kN) - Displacement (m) applied compressive load 1,200 kN at 4 corner nodes of higher level.
http://postimg.org/image/4ix16x4o3/
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the maximum value of the chart without applying prestressing was
900.62 kN for displacement 0.1296 m
the maximum value of the chart by applying compressive load 1200 kN at 4 corner points of the maximum level is
995.46 kN for displacement 0.1188 m
improvement in bearing capacity is
995.46 - 900.62 = 10.5%
result
there is a slight improvement in the bearing capacity of the building, through the application of compressive forces in the four corner columns of the building.