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Concrete toolbar

Concrete toolbar
 
After loading a .rcf result file, the user can perform a code check or design . By clicking on the corresponding icon, the user will be able to select the desired option.
 
After choosing the kind of checking or design option (Axial, bending, torsion, shear, etc), CivilFEM will generate a new kind of file with the extension .crcf that can be loaded in the Results tab. Opening this file will generate a whole new result list that will contain the obtained checking/design results.
 
1

Check beams button

1. Check beams button
Check the concrete beams according to the active code
 
Checks are carried out in order to verify if structure passes the code provisions under loads.
 
The active code is specified into environment ribbon, under the "C

odes  Standards toolbar".

 
Axial Bending
 
Both Concrete steel and Steel stress utilities define maximum resistance values depending on the user preferences. If no value is entered, CivilFEM will take the theoretical values specified in the standards.
 
Dirkey option defines the bending plane to be checked.
 
In Code option, the standard that has been chosen by the user is specified.
 
Shear & Torsion
 
Code option specifies the standard that has been chosen by the user.
 
Shear QY, Shear QZ and Torsion checks may be carried out together or one by one depending on the required analysis.
 
Cracking
 
Code option specifies the standard that has been chosen by the user.
 
Dirkey option defines the bending plane to be checked.
 
Axial Bending (Prestress)
 
Checking of elements in axial force and biaxial bending is made in the following steps: 
1.     Obtaining the acting forces and moments of the section (FXd, MYd, MZd) of which the primary prestressing forces and moments are subtracted (Fxiso, Myiso or Mziso). The acting forces and moments are obtained, after making a calculation, directly from the CivilFEM results file (file .RCV).
2.     Construction of the interaction diagram of the section. From the diagram, that contains all the ultimate pairs of forces and moments (Fu, Mu) of the cross section, the ultimate strain state homothetic to the acting point (point P) with respect to the diagram center is determined (see the previous section for the determination of the diagram center).
 
3.     Obtaining the strength criterion of the section. This criterion is defined as the ratio between the distance of the “center” of the diagram (point A of the figure) to the point which represents the acting forces and moments (point P of the figure) and to the point which represents the homothetic ultimate forces and moments (point B).
 
All checks include the "All model" utility. This option allows the user to select a part of the structure for performing the check.
 
 
A .crcf file, which must be opened in order to visualize results, will be created.
 
2

Design beams button

2. Design beams button
Design the concrete beams according to the active code
 
The active code is specified into environment ribbon, being this tool contained in the "C

odes Standards toolbar".

 
Axial Bending
 
Both Concrete steel and Steel stress utilities, define maximum resistance values depending on the user preferences. If no value is entered, CivilFEM will take the theoretical values specified in the standards.
 
Dirkey option defines the bending plane to be checked.
 
In Code option, the standard that has been chosen by the user is specified.
 
Both Minimum and Maximum amount limits the upper and lower reinforcement amount that CivilFEM is allowed to use in the calculations of scalable reinforcement.
 
  • The scalable reinforcement concept is explained in the Concrete sections, contained in the Modal toolbar menu.
 
Code option specifies the standard that has been chosen by the user.
 
Dirkey option defines the bending plane to be checked.
 
Shear & Torsion
 
Code option specifies the standard that has been chosen by the user.
 
Shear QY, Shear QZ and Torsion design may be carried out together or one by one depending on the required analysis.
 
 
Both checks include the "All model" utility. This option allows the user to select a part of the structure for performing the check.
 
 
3

Check shells button

3. Check shells button
Check the concrete shells according to the active code
 
Checks are carried out in order to verify if structure passes the code provisions under loads.
 
CEB-FIP
 
Design under Bending Moment and In-Plane Loading:
 
  • The reinforcement design of shells under bending moment and in plane loading is accomplished by Model Code CEB-FIP 1990.
  • Reinforcements are defined as an orthogonal net (directions of this net are taken as element X and Y axis).
 
The shell is considered to be divided in three, ideal layers. The outer layers provide resistance to the in-plane effects of both bending and in-plane loading; the inner layer provides for a shear transfer between the outer layers.
 
In CEB-FIP, the only one necessary to carry out the check of a shell is the .rcf archive.
 
Orthogonal dir
 
The calculation hypothesis in the orthogonal direction method is:
 
  • The design of reinforcement for bending moments and axial forces is performed independently for each direction.
  • Reinforcement is defined as an orthogonal mesh (directions of this mesh are taken as element X and Y axes).
 
The Maximum stress allowed in reinforcement is specified so that it will be taken into account in the solving process.
 
On the other hand, forces and moments that are going to be applied must be assigned in Forces and moments used option.
 
 
Unfavorable dir
 
The objective of this design method is to calculate the reinforcement requirement of concrete shells with a method based on the one proposed by CAPRA-MAURY; this method accounts for bending moments (Mx, My) and torsional moments (Mxy) as well as axial forces (Tx, Ty) and in-plane shear forces (Txy).
 
Depending on the active code, the checking is performed using the pivot diagram described for the check concrete cross sections.
 
The Maximum stress allowed in reinforcement is specified so that taking it into account in the solving process.
 
Out-of-Plane shear
 
The goal is executing a shear check out of the shell plane (so called transverse forces). Out of plane shear check is available for the different codes that are implemented in CivilFEM, therefore the calculation process will change depending on the standard used.
 
There are no specific parameters to perform this type of check. Only the .rcf result file is needed.
 
In plane shear
 
The aim is performing a shear check in the shell plane. In plane shear check is available for the different codes that are implemented in CivilFEM, therefore the calculation process will change depending on the standard used.
 
There are no specific parameters to perform this type of check. Only the .rcf result file is needed.
 
Cracking
 
This check type performs a cracking check by code so as to evaluate the cracking effect. Calculation process is subject to change depending on the standard used. For this reason, in Checking/Design data option, user will find different parameters that vary according to the selected standard.
 
Both checks include the "All model" utility. This option allows the user to select a part of the structure for performing the check.
 
 
A .crcf file, which must be opened in order to visualize results, will be created.
 
4

Design shells button

4. Design shells button
Design the concrete shells according to the active code
 
Shell design tool evaluates the concrete compression criterion in relation to the provided reinforcement. Thus, CivilFEM will warn the user if the section reinforcement is not enough to withstand the loads.
 
Wood-Armer
 
Two different hypothesis are taken into consideration in this design type:
 
  • The reinforcement design of shells under bending moments is accomplished by the method developed by R.H. Wood and G.S.T. Armer.
  • Once the reinforcement design moments have been calculated, a design for flexure is performed for each shell vertex.
 
In Wood Armer, the user has to specify the .rcf archive. No further parameters are needed.
 
CEB-FIP
 
Two different hypothesis are taken into consideration in this design type:
 
  • The reinforcement design of shells under bending moment and in plane loading is accomplished by Model Code CEB-FIP 1990.
  • Reinforcements are defined as an orthogonal net (directions of this net are taken as element X and Y axes).
     
In CEB-FIP, the user has to specify the .rcf archive. No further parameters are needed.
 
Orthogonal dir.
 
Two different hypothesis are taken into consideration in this design type:
 
  • The design of reinforcement for bending moments and axial forces is performed independently for each direction.
  • Reinforcements are defined as an orthogonal mesh (directions of this mesh are taken as element X and Y axes).
 
Unfavorable dir.
 
The objective of this design method is calculating the reinforcement requirement of the concrete shells with a method based on the one proposed by CAPRA-MAURY.
 
The Maximum stress allowed in reinforcement can be specified.
 
Depending on the active code, the design is performed using the pivot diagram method.
 
In Plane Shear
 
The objective of this design method is to calculate the reinforcement requirement of concrete shells using the method proposed by CAPRA-MAURY.
 
There are not many parameters to consider if this method is used; in fact, only the .rcf result file is needed for CivilFEM.
 
5

Interaction diagram button

5. Interaction diagram button
Plot the interaction diagram
 
The interaction diagram is a curve in space that contains the forces and moments (axial load, bending moment) corresponding to the shell ultimate strength states. In CivilFEM the ultimate strength states are determined through the pivots diagram.
 
A pivot is a strain limit associated with a material and its position in the shell vertex. If the strain in a section pivot exceeds the limit for that pivot, the shell vertex is considered cracked. Thus, pivots establish the positions of the strain plane. So, in an ultimate strength state, the strain plane includes at least one pivot of the shell vertex.
 
 
In CivilFEM, pivots are defined as material properties and these properties (pivots) are extrapolated to all the points through the thickness of the shell vertex, accounting for the particular material of each point (concrete or reinforcement). Therefore, for the section strain plane determination, the following pivots and their corresponding material properties will be considered:
 
A Pivot
EPSmax. Maximum allowable strain in tension at any point of the shell vertex (the largest value of the maximum strains allowable for each point of the section in case different materials in the section exist).
B Pivot
EPSmin.  Maximum allowable strain in compression at any point of the section (the largest value of the maximum strains allowable for each point of the section).
C Pivot
EPSint. Maximum allowable strain in compression at the innner points of the section.
 
Beams & Shells
 
In order to design an interaction diagram, it is necessary to specify both an element and an extreme of the concrete body that will be analyzed. This criterium must be followed not only in beam diagrams but in shell ones also.
 
Concrete and steel stresses establish the maximum stresses for diagram creation. If no value is chosen, CivilFEM will take the default material values.
 
Dirkey option define in which plane, or direction, the concrete body is going to be analyzed.
 
An example of a shell diagram:
 
As shown in the diagram, the criterion is under 1, so the concrete shell withstands the working load.
 
Beams (Prestressed)
 
The procedure is similar to the previous interaction diagram defined but taken into account:
 
In the calculation of total prestressing steel strains, apart form the strain produced in the corresponding ultimate state deformation plane fiber, the prestressing strain and the decompression strain are also considered:
 
 
Where:    
Concrete decompression strain at the considered reinforce level
Prestressing steel strain due to the prestressed action in the considered phase, considering the losses that have taken place.
The strain decompression calculation is carry out taking into account the initial prestressed on the effective section and the long term losses on the homogenize section. 
 
To determine the strains plane (ultimate strength plane) of the section. εg and θ are used as independent variables. The process is composed of the following steps:
1.     Pivots calculation for each the cross section points are based on the associated material, its position within the cross section and the prestressed in case of the prestressing steel.
2.     From the total pivots number  a deformation planes sweeping is made passing through some of the pivots (without going through any of them).
3.     Each one of the strain planes (ultimate strength plane) correspond with a curvature and a strain in the section’s center of gravity and determine the deformation corresponding to each of the section points ε(y).
4.     From the ε(y) strain and the prestressing steel pre-deformations, the stress corresponding to each point of the section (σp) is calculated entering in the material stress-strain diagram of each point. This way, the stress distribution inside the section is determined.
 
Stress determination in a point
5.     So, as the stress distribution is known, the corresponding ultimate forces and moments (Fu, Mu), are obtained by the summation of stresses on each one of the sections point multiplied by its corresponding weight according to the considered flexion axis.    
Where:
NP
Number of points of the section.
WFX, WMY, WMZ
Weights of each section points.
The contribution of the prestressing steel is added to these forces and moments.
 
6.     From the ultimate obtained  forces and moments a distribution of those is made to obtain the closed curve that defines the diagram.