PILE CAPS

 

 

The aim of this utility is to accurately check pile caps and design the configuration of piles. The three options include:

 

• Polygonal Pile Caps
• Rectangular Pile Caps
• Load Test Pile

 

The created model will have defined components in order to manipulate it easily.

 

 

POLYGONAL PILE CAPS

 

This type of pile wailing has the following characteristics:

 

·         Circular or regular polygonal slab.

·         All piles must be circular with the same characteristics.

·         The structure will be under the loads transmitted by a circular or rectangular pillar that will be located at the centre of the slab, in addition to its self weight and to a possible surface load extended on the entire slab.

·         The terrain can be made up by one or several horizontal layers and each one of them can be cohesionless or cohesive.

·         The slab is modeled using SHELL43 elements and the piles by BEAM4 elements.

·         The simulation of the friction with the terrain, the point effect and the horizontal ballast module (reaction of the terrain on the piles) is done with LINK8 elements with plasticity to simulate the situation in which the ultimate strength values are reached.

·         The reinforcement design can be done in two ways:

o   Rigid Pile Caps. In this case the Strut and Tie method is used, explained in the Theory Manual.

o   Flexible Pile Caps. In this case the user can choose between the Wood-Armer method and the one of the CEB-FIP Model code.

 

 DATA ENTRY

 

The window for this pile cap design is made up by a series of sections, shown by the labels at the top of the screen:

 

• Geometry
• Loads
• Reinforcement
• Soil
• Configuration
• Solution
• Calculate length

 

The data entry is done in a simplified way, through interactive windows and guided by the program.

The meaning of each parameter or data to enter is explained by moving the cursor over the corresponding text (a tool tip will appear), although it is recommended to read the Theory Manual for a better understanding of what the program is doing.

 

NOTE: If in the spread list appears a ND> it means that the value is not defined correctly:

 

 

 

Following, the windows CivilFEM will show for the data entry are shown.

 

 

GEOMETRY

 

In the first window, the slab geometry is defined, number of piles, etc.

 

 

Clicking Preview bottom it will open a preview window like herein below:

 

 

 

 

LOADS

 

The loads on the slab are defined in the second screen (Forces and moments, surface load, type of loads, etc.).

 

 

 

REINFORCEMENT

 

This tab groups the reinforcement type parameters.

 

The window will change depending on the type of wailing chosen: rigid or flexible.

 

 

 

 

SOIL

 

To finish defining the model, it is necessary to select the layered terrain on which the pile cap is defined. A few additional parameters must also be set.

 

 

 

CONFIGURATION

 

The configuration parameters include Mesh control parameters and convergence and tolerance for the iterations. Default values can be set.

 

 

 

SOLUTION

 

Under this tab, the design final values are shown.

 

 

“Load Ansys results” button loads previous obtained results after pressing Solve button.

 

“Pile Strength graph” button shows the pile strength graph in Ansys. It is necessary to have the results previously loaded with the “Load Ansys results” button.

 

 

 

 

CALCULATE LENGTH

 

Clicking on the “Calculate length” button in the main dialog opens the CivilFEM window to predesign the pile length necessary for the chosen materials, loads and terrains.

 

It is possible to calculate this length as many times as needed changing the parameters in the window. Once we get the desired length we click on the “Apply and exit” button.

 

 

 

 

 

 

PARAMETER EXPLANATION

 

 

GEOMETRY TAB

 

HeightEn	Upper pile cap height.
HeightPil	Head pile height.
RadPol	Pile cap radius.
RadPil	Pile situation radius.
NumPil	Number of pile.
LenPil	Pile length.
DiaPil	Pile diameter.
Slab Type	Polygonal or circular.
WidPla	Slab width.
Column Shape Type	Circular or rectangular.
X	X dimension column (if rectangular).
Y	Y dimension column (if rectangular).
Diameter	Column diameter (if circular).
MatSh	Slab material.
MatPil	Pile material.
MatRein	Reinforcement material.

 

 

LOADS TAB

 

GammaF	Load Factor.
Fx	X axis force.
Fy	Y axis force.
Fz	Z axis force.
Mx	X axis moment.
My	Y axis moment.
Mz	Z axis moment.
AcelX	X gravity acceleration.
AcelY	Y gravity acceleration.
AcelZ	Z gravity acceleration.
Qslab	Pressure on slab.
	Geotechnical/Structural pile maximum stress

 

 

REINFORCEMENT TAB

 

Reinforcement method.

-          Rigid pile cap (strut and tie).

-          CEB method.

-          Wood-Armer method.

Reinforcement shape (Circular or Polygonal).

Bars

-          Braced

-          Reinforced piles

SlCov	Slab geometrical cover.
PilCov	Pile geometrical cover.
FacArs	Secondary reinforcement factor (strut and tie method).
FacAsu	Secondary upper reinforcement factor (strut and tie method).
k1	Concrete compression strength factor (strut and tie method).
k2	Steel elastic limit security factor (default value = 0.92).
k3	Stirrups analysis factor.

 

 

SOIL TAB

 

General Properties and geometry:
Ueth	Terrain number.
Name	Terrain name.
Nlayer	Number of layers.
Layer Properties:
Layer	Selected layer number.
Mat	Selected layer material.
Thick	Selected layer thickness.
HeifhtT	Terrain height.
Method	Horizontal ballast module method.
HBM	Horizontal ballast module.
Group effect	Taking or not into account group effect.
User defined	Group effect coefficients defined by user.
l	Cohesion coefficient if l=1 cohesive soil, if >1 cohesionless).
fs	Unitary skin friction.
fs*	Unitary skin friction with group effect.
Ncb	Bearing capacity factor.
hs	Skin subsidence group effect coefficient
fp	Unitary point resistance.
fp*	Unitary point resistance with group effect.
hp	Point subsidence group effect coefficient.
g	Shaft deformability factor.
Ws	Skin displacement.
Ws*	Skin displacement with group effect.
hs	Skin settlement group effect coefficient.
d	Settlement factor.
Wp	Point displacement.
Wp*	Point displacement with group effect.
hp	Point settlement group effect coefficient.
Soil Properties:
c	Cohesion.
f	Internal friction angle.
NSPT	Number of blows obtained in the Standard Penetration Test.
	Unconfined compressive strength.

 

 

CONFIGURATION TAB

 

Mesh Parameters:
DivH	Slab horizontal division’s size.
DivV	Pile vertical division’s size.
Parameters:
Psi	Et/E springs ratio.
a	Slab decrease ratio.
Soil Parameters for cohesive graph:
	Cohesion limit for cohesive soils.
	Internal friction angle limit for cohesive soils.
Convergence:
CNVU	Displacement convergence criterion.
CNVF	Forces convergence criterion,
CNVM	Bending moment’s convergence criterion.
Delft Coefficients:
a1	Delft passive coefficient.
a2	Delft active coefficient.
a3	Delft safety coefficient.
Soil Type	Cohesive or cohesionless.

 

 

SOLUTION TAB

 

Piles maximum forces and moments:
MaxAxial	Maximum axial force.
MaxShear	Maximum shear force.
MaxBending	Maximum bending force.
Reinforcement:
NpiH	Axial force limit of concrete pile.
NpiS	Axial force limit of reinforcement pile.
AsPil	Axial+Bending reinforcing steel in piles.
AsPilS	Shear reinforcing steel in piles.
AsPl	Steel in primary reinforcement.
AsSL	Steel in secondary reinforcement.
AsSu	Steel in upper reinforcement.
Asu	Stirrups reinforcement.
StrutA	Strut compression area.
NS	Strut compression axial force.
StrutStr	Strut compression axial force capacity.
WidPla	Minimum shell thickness needed.

 

CALCULATE LENGTH

               

Eta coefficients (Subsidence)
hs	Subsidence Eta skin factor.
hp	Subsidence Eta point factor.
Eta coefficients (Settlement)
hs	Settlement Eta skin factor.
hp	Settlement Eta point factor.
Security Factors
Fs	Security skin factor.
Fp	Security point factor.
Fl	Load security factor.
Predesign results
LenPil	Pile length calculated.

 

RELATED COMMANDS:

~GTPD

 

 

RECTANGULAR PILE CAPS

 

This type of pile cap has the following characteristics:

 

·         Rectangular slab.

·         All piles must be circular with the same characteristics.

·         The pillar must be rectangular and can be located anywhere of the slab.

·         The structure will be under the loads transmitted by the pillar in addition to its self weight and to a possible surface load extended on the entire slab.

·         The terrain can be made up by one or several horizontal layers and each one of them can be cohesionless or cohesive.

·         The slab is modeled using SHELL43 elements and the piles by BEAM4 elements.

·         The simulation of the friction with the terrain, the point effect and the horizontal ballast module (reaction of the terrain on the piles) is done with LINK8 elements with plasticity to simulate the situation in which the ultimate strength values are reached.

·         The reinforcement design can be done in two ways:

o   Rigid Pile Cap. In this case the Strut and Tie method is used, explained in the Theory Manual.

o   Flexible Pile Cap. In this case the user can choose between the Wood-Armer method and the one of the CEB-FIP Model code.

 

DATA ENTRY

 

The data entry is done in a simplified way similar to previous option, through interactive windows and guided by the program.

The meaning of each parameter or data to enter is explained by moving the cursor over the corresponding text (a tool tip will appear), although it is recommended to read the Theory Manual for a better understanding of what the program is doing.

 

NOTE: If in the spread list appears a ND> it means that the value is not defined correctly:

 

 

 

The window for this pile cap design is made up by a series of sections, shown by the labels at the top of the screen:

 

• Geometry
• Loads
• Reinforcement
• Soil
• Configuration
• Solution
• Calculate length

 

Following, the windows CivilFEM will display for the data entry are shown.

 

 

GEOMETRY

 

In the first window, the slab geometry is defined, number of piles, etc.

 

 

Clicking Preview bottom it will open a preview window like herein below:

 

 

 

LOADS

 

The loads on the slab are defined in the second screen (Forces and moments, surface load, type of loads, etc.).

 

 

 

REINFORCEMENT

 

This tab groups the reinforcement type parameters.

 

 

 

SOIL

 

To finish defining the model, it is necessary to select the layered terrain on which the pile cap is defined. A few additional parameters must also be set.

 

 

 

CONFIGURATION

 

The configuration parameters include Mesh control parameters and convergence and tolerance for the iterations. Default values can be set.

 

 

 

SOLUTION

 

Under this tab, the design final values are shown.

 

 

“Load Ansys results” button loads previous obtained results after pressing the “Solve” button.

 

“Pile Strength graph” button shows the pile strength graph in Ansys. It is necessary to previously load the results through the “Load Ansys results” button.

 

CALCULATE LENGTH

 

Clicking on the “Calculate length” button in the main dialog opens the CivilFEM window to predesign the pile length necessary for the chosen materials, loads and terrains.

 

It is possible to calculate this length as many times as needed changing the parameters in the window. Once we get the desired length we click on the Apply and exit button.

 

 

PARAMETER EXPLANATION

 

 

GEOMETRY TAB

 

HeightEn	Upper pile cap height.
HeightPil	Head pile height.
WidPla	Slab width.
LenPil	Pile length.
DiaPil	Pile diameter.
Npx	Number of piles in X axis.
Npy	Number of piles in Y axis.
Column geometry
XWide	X wide column
YWide	Y wide column
Xpos	X position column
YPos	Y position column
Borders
DextL	Left slab flange as picture shows.
DextR	Right slab flange as picture shows.
DextB	Bottom slab flange as picture shows.
DextT	Top slab flange as picture shows.
MatSh	Slab material.
MatPil	Pile material.
MatRein	Reinforcement material.

 

 

LOADS TAB

 

GammaF	Load Factor.
Fx	X axis force.
Fy	Y axis force.
Fz	Z axis force.
Mx	X axis moment.
My	Y axis moment.
Mz	Z axis moment.
AcelX	X gravity acceleration.
AcelY	Y gravity acceleration.
AcelZ	Z gravity acceleration.
Qslab	Pressure on slab.
	Geotechnical/Structural pile maximum stress

 

 

REINFORCEMENT TAB

 

Reinforcement method.

-          CEB method.

-          Wood-Armer method.

Bars

-          Braced.

-          Reinforced piles.

 

SlCov	Slab geometrical cover.
PilCov	Pile geometrical cover.

 

 

SOIL TAB

 

General Properties and geometry:
Ueth	Terrain number.
Name	Terrain name.
Nlayer	Number of layers.
Layer Properties:
Layer	Selected layer number.
Mat	Selected layer material.
Thick	Selected layer thickness.
HeifhtT	Terrain height.
Method	Horizontal ballast module method.
HBM	Horizontal ballast module.
Group effect	Taking or not into account group effect.
l	Cohesion coefficient if l=1 cohesive soil, if >1 cohesionless).
fs	Unitary skin friction.
fs*	Unitary skin friction with group effect.
Ncb	Bearing capacity factor.
hs	Skin subsidence group effect coefficient.
fp	Unitary point resistance.
fp*	Unitary point resistance with group effect.
hp	Point subsidence group effect coefficient.
g	Shaft deformability factor.
Ws	Skin displacement.
Ws*	Skin displacement with group effect.
hs	Skin settlement group effect coefficient.
d	Settlement factor.
Wp	Point displacement.
Wp*	Point displacement with group effect.
hp	Point settlement group effect coefficient.
Soil Properties:
c	Cohesion.
f	Internal friction angle.
NSPT	Number of blows obtained in the Standard Penetration Test.
	Unconfined compressive strength.

 

 

CONFIGURATION TAB

 

Mesh Parameters:
DivH	Slab horizontal division’s size.
DivV	Pile vertical division’s size.
Parameters:
Psi	Et/E springs ratio.
a	Slab decrease ratio.
Soil Parameters for cohesive graph:
	Cohesion limit for cohesive soils.
	Internal friction angle limit for cohesive soils.
Convergence:
CNVU	Displacement convergence criterion.
CNVF	Forces convergence criterion,
CNVM	Bending moment’s convergence criterion.
Delft Coefficients:
a1	Delft passive coefficient.
a2	Delft active coefficient.
a3	Delft safety coefficient.
Soil Type	Cohesive or cohesionless.

 

 

SOLUTION TAB

 

Piles maximum forces and moments:
MaxAxial	Maximum axial force.
MaxShear	Maximum shear force.
MaxBending	Maximum bending force.
Reinforcement:
NpiH	Axial force limit of concrete pile.
NpiS	Axial force limit of reinforcement pile.
AsPil	Axial+Bending reinforcing steel in piles.
AsPilS	Shear reinforcing steel in piles.

 

 

CALCULATE LENGTH

 

Eta coefficients (Subsidence)
hs	Subsidence Eta skin factor.
hp	Subsidence Eta point factor.
Eta coefficients (Settlement)
hs	Settlement Eta skin factor.
hp	Settlement Eta point factor.
Security Factors
Fs	Security skin factor.
Fp	Security point factor.
Fl	Load security factor.
Predesign results
LenPil	Pile length calculated.

 

 

RELATED COMMANDS:

~GTPD

 

 

 

LOAD TEST PILE

 

Unlike the previous options, this utility is to allow the design and checking of only a pile with the following characteristics:

 

·         Pile must be circular.

·         The loads are applied on the pile.

·         The terrain can be made up by one or several horizontal layers and each one of them can be cohesionless or cohesive.

·         The pile is modeled using BEAM4 elements.

·         The simulation of the friction with the terrain, the point effect and the horizontal ballast module (reaction of the terrain on the piles) is done with LINK8 elements with plasticity to simulate the situation in which the ultimate strength values are reached.

 

DATA ENTRY

 

The window for this pile cap design is made up by a series of sections, shown by the labels at the top of the screen:

 

• Geometry
• Loads
• Reinforcement
• Soil
• Configuration
• Solution
• Calculate length

 

The data entry is done in a simplified way, through interactive windows and guided by the program.

The meaning of each parameter or data to enter is explained by moving the cursor over the corresponding text (a tool tip will appear), although it is recommended to read the Theory Manual for a better understanding of what the program is doing.

 

NOTE: If in the spread list appears a ND> it means that the value is not defined correctly:

 

 

 

Following, the windows CivilFEM will show for the data entry are shown.

 

 

GEOMETRY

 

In the first window, the slab geometry is defined, number of piles, etc.

 

 

 

LOADS

 

The loads on the slab are defined in the second screen (Forces and moments, type of loads, etc.).

 

 

 

REINFORCEMENT

 

The reinforcement cover is defined in this tab.

 

 

 

SOIL

 

To finish defining the model, it is necessary to select the layered terrain on which the cap is defined. A few additional parameters must also be set.

 

 

 

CONFIGURATION

 

The configuration parameters include Mesh control parameters and convergence and tolerance for the iterations.

 

 

 

SOLUTION

 

Under this tab, the design final values are shown.

 

 

“Load Ansys results” button loads previous obtained results after pressing the Solve button.

 

“Pile Strength graph” button shows the pile strength graph in Ansys. It is necessary to previously load the results through the “Load Ansys results” button.

 

 

CALCULATE LENGTH

 

Clicking on the “Calculate length” button in the main dialog opens the CivilFEM window to predesign the pile length necessary for the chosen materials, loads and terrains.

 

It is possible to calculate this length as many times as needed changing the parameters in the window. Once we get the desired length we click on the Apply and exit button.

 

 

 

 

 

 

PARAMETER EXPLANATION

 

 

GEOMETRY TAB

 

HeightPil	Head pile height.
LenPil	Pile length.
DiaPil	Pile diameter.
MatPil	Pile material.
MatRein	Reinforcement material.

 

 

LOADS TAB

 

GammaF	Load Factor.
Fx	X axis force.
Fy	Y axis force.
Fz	Z axis force.
Mx	X axis moment.
My	Y axis moment.
Mz	Z axis moment.
AcelX	X gravity acceleration.
AcelY	Y gravity acceleration.
AcelZ	Z gravity acceleration.
	Geotechnical/Structural pile maximum stress

 

 

REINFORCEMENT TAB

 

PilCov

Pile geometrical cover.

 

 

SOIL TAB

 

General Properties and geometry:
Ueth	Terrain number.
Name	Terrain name.
Nlayer	Number of layers.
Layer Properties:
Layer	Selected layer number.
Mat	Selected layer material.
Thick	Selected layer thickness.
HeifhtT	Terrain height.
Method	Horizontal ballast module method.
HBM	Horizontal ballast module.
Group effect	Taking or not into account group effect.
l	Cohesion coefficient if l=1 cohesive soil, if >1 cohesionless).
fs	Unitary skin friction.
fs*	Unitary skin friction with group effect.
Ncb	Bearing capacity factor.
hs	Skin subsidence group effect coefficient.
fp	Unitary point resistance.
fp*	Unitary point resistance with group effect.
hp	Point subsidence group effect coefficient.
g	Shaft deformability factor.
Ws	Skin displacement.
Ws*	Skin displacement with group effect.
hs	Skin settlement group effect coefficient.
d	Settlement factor.
Wp	Point displacement.
Wp*	Point displacement with group effect.
hp	Point settlement group effect coefficient.
Soil Properties:
c	Cohesion.
f	Internal friction angle.
NSPT	Number of blows obtained in the Standard Penetration Test.
	Unconfined compressive strength.

 

 

CONFIGURATION TAB

 

Mesh Parameters:
DivH	Slab horizontal division’s size.
DivV	Pile vertical division’s size.
Parameters:
Psi	Et/E springs ratio.
a	Slab decrease ratio.
Soil Parameters for cohesive graph:
	Cohesion limit for cohesive soils.
	Internal friction angle limit for cohesive soils.
Convergence:
CNVU	Displacement convergence criterion.
CNVF	Forces convergence criterion.
CNVM	Bending moment’s convergence criterion.
Delft Coefficients:
a1	Delft passive coefficient.
a2	Delft active coefficient.
a3	Delft safety coefficient.
Soil Type	Cohesive or cohesionless.

 

 

SOLUTION TAB

 

Piles maximum forces and moments:
MaxAxial	Maximum axial force.
MaxShear	Maximum shear force.
MaxBending	Maximum bending force.
Reinforcement:
NpiH	Axial force limit of concrete pile.
NpiS	Axial force limit of reinforcement pile.
AsPil	Axial+Bending reinforcing steel in piles.
AsPilS	Shear reinforcing steel in piles.

 

 

CALCULATE LENGTH

           

Eta coefficients (Subsidence)
hs	Subsidence Eta skin factor.
hp	Subsidence Eta point factor.
Eta coefficients (Settlement)
hs	Settlement Eta skin factor.
hp	Settlement Eta point factor.
Security Factors
Fs	Security skin factor.
Fp	Security point factor.
Fl	Load security factor.
Predesign results
LenPil	Pile length calculated.

 

 

RELATED COMMANDS:

~GTPD

 

 

 

DEFINED COMPONENTS

 

 

When solving the next components are created, the which can be browsed through the Component Manager tool of Ansys: