2. Overview of the design procedure

2.1 Exporting data from ETABS 2019-current version

The procedure of exporting data from ETABS 2019-current is handled automatically by ECtools – ETABS API communication.

The user simply provides ECtools with the appropriate file path.

The file should be solved and opened in ETABS during the design process.

For ETABS versions prior to v2019 information can be found in our manuals

2.2 Project file creation

The program has the capability to store all the data of a project in a separate file of the form .etp, which includes all the design options (described in latter sections), the locations of the Input and Output files on the hard drive and additional information that can be entered by the user from File -> Project information.

- Project name

- Location

- Client

- Designer

- Project type (new construction, existing, strengthening)

- Project phase (preliminary, final design)

- Project date

- Deadline

- Additional comments

File ->  Open project file : Opens a stored project file (.etp extension) from the hard drive. Also, an .etp file can open in ECtools by double-clicking.

File ->  Save project file : Saves the current project (settings, additional information, etc.) in a file of the form .etp. It is noted that the project file does not need to be saved in the same folder with the Input, Output and section files. The following folder structure is recommended for the project folders :

File ->  Create compressed project file (zip) : Creates a compressed .zip file that includes all the files in the project folder. The user is initially prompted for the .etp file of the project and then a .zip file is created having the same name in the project folder. This function is particularly useful for easy exchange of all the project files between different users.

2.3 General Options

The program options window is opened from the navigator  General options :

- Create log file : The user can select if a full results file is to be created after the design is complete, and can define the file name. The full results file includes separate results for all the load combinations and not only for the most onerous ones that appear in the design calculations issue.

- Language: The user has the option to select from a list of available languages for the creation of the design report:

- Relabel: Enables relabelling of the model frames this will be explained extensively later in this manual.

- Create 3d Model : Enables the creation of a 3d model in the main window consisting of the elements that are to be designed . This mode is only available via the API for ETABS or via the xml for S.EN . The reason is that ECtools draws all the necessary geometry through the clients model created in the parent software that the client uses.

2.4 Design options

The design options window opens from the navigator  Design options :

-  Design Code: The design can be performed according to Eurocode 2 (Eurocode 2 option) provisions only, or the Combination of Eurocode 8 and Eurocode 2 (Eurocode 8 option). Additional information is provided in the Eurocode Theory Manual.

-  Ductility Class: For Eurocode 8 design option, the desired ductility class of the building should be selected, either Ductility Class Medium or Ductility Class High.

-  Structural System: For Eurocode 8 design option, the structural system has to be defined in order to calculate the behaviour factor q.

q=q­_ok_w

The structural system is automatically defined according to the features of the ETABS/S.EN. model as following, unless it is an uncoupled wall system, an inverted pendulum or there is irregularity in elevation and hence the user has to declare it.

The basic structural systems are shown in the following table along the selection criteria for each system.

- q_o override: The user can override the automatically calculated q_o factor (and the resulting q factor) with a value different from the one suggested by EC8, since the program automatically selects the maximum allowed value. The override for smaller values of q_o than the code prescribed ones is allowed, while the override for higher values of q_o requires additional documentation and justification such as pushover analysis.

- Control Period T_C: The end corner of the spectra plateau has to be defined in order to calculate the μ_φ factor (local ductility of elements).

- Ignore beam compression: This option allows the design of the RC beams with zero (0) compression force (the tension force is not altered). This option is valuable for models without diaphragm constraint (as in S.EN.) where a compressive axial force for beams may render their design unconservative, or even unsafe.

- Fire design-Environmental conditions : The environmental conditions to which the building is exposed to, are selected according to EC2, which reflects to specific reinforcement cover. This information is used to check if the structural elements conform with EN1992 fire checks for the prescribed fire duration R.

- Checks : The checks (design criteria) that are to be performed according to EC8 are defined. These include 2^nd order effects, joint widths, fill materials, torsionalsusceptibility and omission of joint capacity design checks. See section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε. for additional information.

- Load combinations : The user can choose whether the necessary design load combinations are to be created automatically by ECtools, based on the load cases that have been defined in the ETABS or S.EN. model. Also, the ψ₂ coefficient can be defined and whether the eccentricity load cases are to be included in the above-mentioned combinations. Additional information is provided in section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε..

- Joint capacity design check along the x and y axes : The user can choose whether the joint capacity checks are performed during the structural design. Available options are a) to be dependant on the outcome of the corresponding joint capacity design omission check based on EC8, b) to be always performed irrespectively of the result of the joint capacity design omission check, c) to be omitted irrespectively of the result of the joint capacity design omission check.

- Masonry : The masonry material factor (γ_m) and the ratio between the compressive and tensile capacity (f­_c / f_t) of masonry is entered.

- Foundation level [m] : By definition, each RC wall base is assumed as the founding level of the corresponding Pier that has been defined in the ETABS/S.EN. model (the node with the lesser vertical co-ordinate z). Should the user wish to define a common founding level for all the RC elements in the model, the  level (elevation) that is to be defined as the common founding level is entered in the field. The common RC wall founding level can be altered latter during the design run (described in more detail in section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.).

- National Annex: As it is known the Eurocodes program has allowed some diversification in the application of the Eurocodes at the several member states. These diversifications are achieved through the Nationally Defined parameters which are included at the National Annexes.

2.5 Building Check Options

The Building Check options window is opened from the menu Options 

Building Check options:

For checking an existing structure according to EC2 or EC2 and EC8, the option Enable building Check must be selected and the load and material safety factors to be input in the relevant fields. These factors will replace the default EC2 factors. During the design run the user is prompted for the existing element reinforcements that are entered in table format, so as to perform the individual structural element capacity checks.

2.6 Reinforcing bar diameter sizes

The reinforcing bar diameter sizes window is accessed from the menu Options ->  Rebar sizes :

The user can set limits to the bar sizes to be used as bending reinforcement in beams, columns and RC walls and which will be proposed in the design calculations issue.

2.7 Running the Design

Having entered the Input and Output files in the relevant fields and once the design parameters are set according to the previous sections of this manual (it is recommended at this point to save the project file), the design can be run be clicking on the  Run Design button.

    The design begins by reading the input (via .txt, xml, API), whilst simultaneously information regarding the number of materials, sections, structural elements, etc. contained in that file, is displayed in the adjacent window.

Note : Should an error message appear through reading of the Input file or if the displayed data does not correspond to the ETABS model, it is possible that not all the available data categories (see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.) were selected during the creation of the Input file, or that there is data in the model with names exceeding 9 characters or containing blanks.

    Once the input is read and only in the case the building check option has been activated (see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.), the existing beam and column reinforcement data (for bending and shear) input window is displayed in table format.

 *If the Building Check license has not been activated, then only one indicative beam and column appear in the table.

The user needs to enter the following data :

- Beam bending tab. Existing bending reinforcement :

And, optionally, the local behaviour factor (m) that replaces the global behaviour factor (q) for each beam. - Column bending tab. Existing bending reinforcement :

and the local behaviour factor (m) that replaces the global behaviour factor (q) for each column. Entering the existing bending reinforcement data can be in the form of a single bar size, e.g. 4Φ12 or multiple bar sizes e.g. 4Φ12+2Φ16+... . Moreover, the total area of bending reinforcement in cm2 can be entered, instead of individual bars.

*The latin character ‘F’ or ‘D’ can be used instead of ‘Φ’.

- Beam shear tab. Existing shear reinforcement :

- Column shear tab. Existing shear reinforcement :

Entering the existing shear reinforcement data can be in the form of a single bar size, e.g. Φ10/200 or multiple bar sizes e.g. Φ10/200+2Φ16+... . Additionally, the link legs can be entered in brackets e.g. Φ10/200(4) (if omitted, it is assumed that the link has two legs). Moreover, the ratio of A_s/s can be entered instead of individual bars.

Note 1 : Should any cells be left blank after the process is completed (by clicking on the  Close button), these will be assumed to be zero and also the local behaviour coefficients m will be assigned the value of the global behaviour coefficient q (as entered in the design options, see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.).

Note 2 : Once the process is completed, the tables containing the existing reinforcement data are saved in the folder where the Input and Output files are stored under the name <Input file name>_Checkx.txt (x = 1,2,3,4 referring to the 4 respective tables). This ensures that the table data does not have to be re-entered, should the analysis be rerun, and enables editing of the entered data.

    To assist the manual input of the existing reinforcement data described above, it is possible to follow the procedure previously described in section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε. for multiple creation of masonry elements. Specifically :

1. In each of the four tabs, clicking the Copy  button copies the table data to the Clipboard. The data can then be pasted to a spreadsheet (e.g. Microsoft Excel^®).

 2. The existing reinforcement data for each tab is entered in the spreadsheet as described above. Next, select the whole table (Ctrl-A) and copy (Ctrl-C) and paste it in the relevant tab by clicking the  button.

Next, the data editing window is displayed, where the user can alter the model data before the Output file is read and the design is run. The data editing window includes the following tabs :

- Materials : Displays the material names and properties table included in the model. The following editing options are available :

button : Adds a new material in the table. Material properties are entered in the figure shown on the right. For masonry materials, the f_vko and f_lim properties are entered initially at the f_y and f_ys fields respectively, enabling the program to automatically recognise these as masonry materials.

 

button or double click : Edits the selected material properties. It is also possible to edit multiple materials from the table either by clicking the particular button or by right-clicking on the multiple selection. For multiple material editing, all the selected materials should be of the same type, i.e. all concrete or all masonry.

 

- Sections : Displays the section names and characteristics table contained in the model. The following editing options are available :

button : Adds a new section in the table. Section properties are entered in the window shown on the right. Section type can be rectangular, T-, L-, U- or circular section. Depending on the section type, the relevant data input fields are activated and the section outline is drawn for checking purposes.

 

button or double click : Edits the selected section geometry. It is also possible to edit multiple sections from the table either by clicking the particular button or by right-clicking on the multiple selection. For multiple sections editing, all the selected sections should be of the same type.

 

If the selected section is an RC wall or masonry wall section, then it is opened in the corresponding editor, as described in section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε..

button : Opens the selected section for editing in Nous (see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.). If the section is modified (e.g. by adding a jacket), then it is saved on the hard drive as a .sd file and is entered in the table as a jacketed section by clicking the update  button (described latter on). Also, jacketed sections can be edited in Nous by double-clicking.

 

- Beams / Columns / RC Walls / Masonry Walls : Displays the structural element names and characteristics contained in the model. Editing of structural elements is performed by clicking on the button or by double-clicking for a single selection or by right-clicking for multiple selection.

For beams and columns, only the section names can be modified. The section material will be that of the newly applied section.

For RC walls the section, material (choice of concrete materials only) and base (founding level) name that is to be used in design can be modified. Initially, the founding level of every RC wall is assumed to be the respective Pier base that has been defined in the ETABS model or the common founding level defined in the design options (see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.). For masonry elements, the section and material name (choice of masonry materials only) can be edited.

Note : The sections table displays those jacketed sections that have been created in ETABS Section Designer as polygonal lines with point reinforcements.

- The general options of the data editing window, irrespective of the selected tab, are as follows :

  button or Ctrl-A : Selects all the table data. Clicking again selects only the top row of the table.

  button : Updates the jacketed sections in the table from the files contained in the folder where the Input and Output files are stored. Updating is necessary before the design is run, if any additional jacketed sections are created in Nous.

 button : Replaces existing sections with jacketed sections (strengthened sections) located in the same folder where the Input and Output* files are stored. These strengthened sections are highlighted in green (see figure below) in the column, RC and masonry wall tables. The strengthened section creation process is described in detail in section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε..

^* Requires the Strengthening license to be activated.

button : Updates the ETABS data file (file with a .Ε2Κ or .$ET extension) to all the modifications that have been performed in the data editing tables window. (not available in S.EN. mode)

The ETABS data file name that contains the model is entered in the next window and by clicking the  Update button, the user is prompted for the new file name to be created. This new file can be loaded in the ETABS environment from the menu File -> Import -> ETABS .E2K Text File. It is noted that all the jacketed sections created in Nous, are input as ETABS Section Designer sections. Also, all the changes to the correlations between sections and frame elements that have been performed in the data editing window are incorporated in the new data file.

button : Cancels the design procedure. The information and data editing window is closed and the design process reverts to the starting stage (start of current section).

button : Starts the design process. Once all the necessary changes have been performed in the data editing window, the process moves on to read the results file (Output) and perform the design.

Note : All the columns displayed in the window can be alphabetically sorted by left-clicking on the title of each column. By clicking again, the column is sorted in reverse alphabetical order. The title of the sorted column is displayed in bold.

Running the design – Reading the results (Output)

Depending on the selected options, the following windows for additional data input are displayed when the design is run :

- Load case correlation : If the automated creation of loading combinations has been selected in the design options (see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.) the user is asked to correlate the load cases created in ETABS with the G, Q, Ex, Εy, MEx and MΕy load cases (the last two are asked for only if eccentricity load cases have been selected).

Note 1 : ETABS load cases that are correlated in the above window are not included in the design as stand alone load cases.

Note 2 : For designs according to EC2 + EC8, even if the automated creation of load combinations has not been selected in the design options, the user is prompted to correlate the load cases G, Q, Ex and Εy for performing the various checks against the clauses of the Eurocodes.

- Define additional earthquake load combinations: For designs according to EC2 + EC8 and for the load cases (and combinations) created in ETABS (except those already correlated in the previous window) the user is prompted for whether these are to be treated as earthquake combinations when designing against EC8. Clicking on the square box () by the load case or combination name selects that case or combination as an earthquake one ().

Design calculations issue

Depending on the number of the structural elements, the load combinations and the speed of the computer used, the design process can be completed in a few seconds to a few minutes. Aggregate data of the design process and a bar-chart indicating the solution time for each element (in milliseconds – ms) are displayed in the information window during the design run. The design calculations issue window is displayed once the design process is complete.

The solution time bar-chart includes the following categories :

button : Displays the beam data. The various colours represent the following :

Beams that have been designed or that are adequate in the cross-section capacity design checks (safety factor larger than unity).

Beams where the maximum reinforcement percentage (Α_max) as defined in the Eurocodes has been exceeded.

Beams where the concrete core shear capacity (V_Rd2) has been exceeded in design.

Beams that are inadequate in the cross-section capacity design checks (safety factor smaller than unity).

button : Displays the column data. The various colours represent:

Columns that have been designed or that are adequate in the cross-section capacity design checks (safety factor larger than unity).

Columns where the maximum reinforcement percentage (Α_max) as defined in the Eurocodes has been exceeded.

Columns where the maximum ratio (v) of applied axial force to axial capacity as defined in the Eurocodes has been exceeded.

Columns where the concrete core shear capacity (V_Rd2) has been exceeded in design.

Columns that are inadequate in the cross-section capacity design checks (safety factor smaller than unity).

button : Displays the RC walls data. The various colours represent:

RC walls that have been designed or that are adequate in the cross-section capacity design checks (safety factor larger than unity).

RC walls where the maximum reinforcement percentage (Α_max) as defined in the Eurocodes has been exceeded.

RC walls where the maximum ratio (v) of applied axial force to axial capacity as defined in the Eurocodes has been exceeded.

RC walls where the concrete core shear capacity (V_Rd2) has been exceeded in design.

RC walls with jacketed section (.sd) that are inadequate in the cross-section capacity design checks (safety factor smaller than unity).

button : Displays the masonry walls data. The various colours represent the following :

Masonry walls that are adequate in the cross-section capacity design checks (safety factor larger than unity).

Masonry walls that are inadequate in the cross-section capacity design checks (safety factor smaller than unity).

Note : In the cases mentioned above, if the section is a jacketed one (.sd extension) or a masonry wall, then the design is not performed but merely a cross-section adequacy check carried out. Consequently, the only possible states in the bar-chart are  (adequate) or  (inadequate).

On the solution time bar-chart the following actions can be performed :

-  Left click -> Displays the selected element in the design calculations issue.

-  Double left click ð Opens the selected element in Nous. This action is useful for creating strengthened sections, as described in section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε..

-  Scroll wheel up/down -> Scrolls through elements up or down respectively.

-  Left button drag -> Zoom in/out on the bar-chart.

-  Right button drag -> Pans up/down on the bar-chart.

When a structural element is selected on the bar-chart, the design/check results are displayed in the design calculations issue window. The name of the selected element is displayed at the lower part of the window in the form
<floor> - <element>. Additional functions are as follows :

button : Opens the selected element in Nous. Performs the same action as double left-clicking on the solution time bar-chart.

button : Displays the full results file, if this has been enabled in general program options (see section Σφάλμα! Το αρχείο προέλευσης της αναφοράς δεν βρέθηκε.).

button : Print preview of the design calculations issue. The following options are available in the print preview window :

  Print

 Printer setup

 Margins (show/hide)

 Previous page

 Next page

Zoom in/out on page

 Close preview

button : Print design calculations issue.

button : Save design calculations issue in rich (.rtf) or plain (.txt) text format.