Etabs tutorial

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1. BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 TUTORIAL FOR DESIGN OF A G+10 BUILDING USING ETABS 2. BY: ASAYE…
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  • 1. BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 TUTORIAL FOR DESIGN OF A G+10 BUILDING USING ETABS
  • 2. BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 Contents 1. Introduction..............................................................................................................................................1 2. Modelling and Analysis.........................................................................................................................2 2.1. Create a New Model......................................................................................................................5 2.2. Define Materials............................................................................................................................12 2.3. Define Sections .............................................................................................................................14 2.4. Add Geometry to the Model......................................................................................................21 2.5. Meshing and Assigning Diaphragm.......................................................................................34 2.6. Define Load Cases and Load Combinations........................................................................39 2.7. Assign Loads..................................................................................................................................46 2.8. Assign Pier Labels........................................................................................................................50 2.9. Define Mass Source and Autoline Constraints....................................................................51 2.10. Assign the Supports.....................................................................................................................53 2.11. Check the Model and Run Analysis........................................................................................54 3. Display the Results...............................................................................................................................56 3.1. Tabular Display.............................................................................................................................56 3.2. Graphical Display.........................................................................................................................60 4. Section Design.......................................................................................................................................65 4.1. Concrete Frame Design..............................................................................................................65 4.2. Shear Wall Design........................................................................................................................69 5. Miscellaneous ........................................................................................................................................73 5.1. Section Designer...........................................................................................................................73 5.2. Curved Beams................................................................................................................................78
  • 3. 1 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 1. Introduction The use of software for analysis and design of civil engineering structures has become indispensable part of many of the complex civil engineering projects. Even though the available software for analysis and design are intended to provide their utmost simplicity, supplementary documents to understand the execution of the analysis and design process may still be crucial. Thus, this tutorial is intended to provide a comprehensive procedure about how to analyze and design reinforced concrete buildings using ETABS. Particularly, designers who are novice for this software will be entertained by this tutorial. The tutorial is comprised of four additional main parts besides this introductory part. To show the procedures, architectural floor plans of a G+10 building will be used. The plans may not be exquisite from architectural point of view but they are still very useful to utilize it for understanding the basic ETABS procedures. The modelling and analysis part covers the all the procedures to create and analyze the building by creating the ETABS model. This includes the procedures about creating a new model, defining materials and sections. After adding the geometry to the model, additional steps which supplement the complete modelling process will be outlined. The final stage of this part will include topics about how to check the model and run the analysis. The second part of the tutorial is about displaying the analysis results. In this part, it will be tried to include different procedures to display the analysis results. The section design part shows how to design concrete frame and shear wall sections using ETABS. The results of ETABS section design may not be strictly followed due to possible building code differences, but they can be helpful to check section designs by other conventional methods. The last part of the tutorial, which is open for further development, includes miscellaneous topics. In this part, ETABS procedures which were not discussed in the previous parts and which might be important in modelling other types buildings will be included. Overall, the tutorial includes the very basic ETABS procedures about how to carry out the analysis and design of a reinforced concrete building and more. Thus, it can be useful for understanding the ETABS software.
  • 4. 2 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 2. Modelling and Analysis In this part of the tutorial, an architectural plan and the input parameters will be given. Then, the step-by-step procedures to create and analyze the model will be followed.
  • 5. 3 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016
  • 6. 4 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 The story heights are: - Foundation column height – 2m - Ground floor story height – 4m - Other (Typical story) heights – 3m
  • 7. 5 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 The section dimensions for columns, beams and shear walls are obtained from the architectural plan. For slabs, the thickness is obtained from deflection requirement. The sections for different structural parts are summarized as below: Columns: Ground floor up to fifth floor Sixth floor up to roof Circular – 500mm diameter Circular – 400mm diameter Rectangular – 400X800mm Rectangular – 300X600mm Beams: Ground floor up to fifth floor Sixth floor up to roof Rectangular – 300X500mm Rectangular – 250X400mm Intermediate beams (For all floors) Rectangular – 250X400mm Shear Wall: For all floors Thickness = 300mm Slab : For all floors Thickness = 230mm There is a live load of 3kN/m2 on all slabs and internal beams from the first floor to the fifth floor. From the sixth to the tenth floor slabs, internal beams and on all stairs and landings, there is a live load of 5kN/m2 . Beams supporting external walls for all floors except the roof floor are subjected to no live load but there is a wall load of 10kN/m. All the slabs and beams on the roof floor are subjected to a live load of 1kN/m2 . The concrete and steel grades which will be used for the design of the whole building are: Concrete – C-30 (30MPa 28 day characteristic cube strength) Steel – S-400 (400MPa characteristic yield strength) The class of works is class-I. The multi-purpose building will be founded on black cotton soil is going to be constructed in coastal earthquake prone area. 2.1. Create a New Model First, open the ETABS program from an appropriate location. Before creating the model, the units which will be used for the design should be set. This is done by selecting a suitable unit from the drop down menu at the bottom right corner of the ETABS window.
  • 8. 6 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 Figure 1. For this design, we will use ‘KN-m’ units and select this unit from the list of units in the drop down menu. To create a new model from the program, there are three ways. a. Go to File >New Model … b. Click on the icon . This icon is the first among the list of icons just below the menu bar. c. Simply click on the Ctrl and N keys simultaneously (Ctrl+N). Performing one of the above three ways results in the popping-up of the following ‘New Model Initialization’ window. Figure 2 This window helps you to choose an initialization method. Select one of the following: • ‘Choose .edb’ button. When this button is clicked, ETABS displays the Open File form. Use that form to select a previously created ETABS file that has an .edb extension and that can be used as the basis for initializing the new model using its definitions and preferences. After a file has been selected on the Open File form, ETABS will display the Building Plan Grid System and Story Data Definition form.
  • 9. 7 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 • ‘Default.edb’ button. This method is similar to the ‘Choose.edb’ method, except that file selection happens automatically. That is, ETABS first attempts to start the new model using definitions and preferences that are specified in a typical ETABS .edb file that has the name Default.edb and that is stored in the same directory as the ETABS.exe so that ETABS can locate the Default.edb automatically. If no Default.edb file is present in that directory, ETABS displays the Building Plan Grid System and Story Data Definition form ; use that form to begin the process of creating the Default.edb file; then store the Default.edb file in the appropriate subdirectory for future use with this option. • ‘No’ button. ETABS displays the Building Plan Grid System and Story Data Definition form. For this particular example, click on ‘No’ button as we will create a new model from the scratch without using existing .edb files. This leads to the following ‘Building Plan Grid System and Story Data Definition’ window. Figure 3 When this window appears, use it to review/modify grid and story dimensions and to choose to use a template to start the model or to use only grid lines. The plan view of the building will be modelled using grids. Thus, the grids will be used to define the location of beams, columns and other structural members horizontally. § ‘Grid Dimensions (Plan)’ options. Choose an option for defining the grid spacing for the model.
  • 10. 8 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 o ‘Uniform Grid Spacing’ option. Specify the number of grid lines in the X and Y directions and a uniform spacing for those lines. Note that the uniform spacing in the X direction can be different from the uniform spacing in the Y direction. This option defines a grid system for the global coordinate system only. o ‘Custom Grid Spacing’ option. This option allows non-uniformly spaced grid lines to be defined in the X and Y directions for the global coordinate system. Choose this option and then click the ‘Edit Grid’ button to access the ‘Define Grid Data’ form. Use that form to label grid lines, specify spacing, appearance and the like. Use this form to label grid lines to match labeling on plans. Regardless of which option is used to initially define grid lines, the grid lines can be edited and additional coordinate/grid systems can be defined in the model using the ‘Edit’ menu > ‘Edit Grid Data’ command. § ‘Story Dimensions’ options. Choose an option for defining the number and height of the stories in the model. o ‘Simple Story Data’ option. When this option is selected, use the defaults or specify values for the Number of Stories, Typical Story Height, and Bottom Story Height in the edit boxes. The value specified for the Typical Story Height will be used for all stories in the model, except the bottom story. ETABS will assign default names to each story. This data can be modified later using the Edit menu > Edit Story Data command. o ‘Custom Story Data’ option. Use this option to manually define story names, story levels of non-uniform height, and story similarity. Click the Edit Story Data button to access the Story Data form. Click directly in the edit boxes to change any of the items. § ‘Units’ drop-down list. Use this drop-down list to select the units for data entry on this form. The selection made here does not affect the base units selected using the drop-down list in the right corner of the Status bar. § Steel Deck, Staggered Truss, Flat Slab, Flat Slab with Perimeter Beams, Waffle Slab, Two Way or Ribbed Slab and Grid Only buttons. Use these buttons to add objects to a model, or to start the model using only a grid system. In most cases, using templates to start a model is the simplest, most convenient and quickest method, although it is not necessary because the other commands in the program can be used to draw, edit, define and assign the necessary components to create a model. Using templates is recommended if the program is new to you. As can be noted from the architectural plan, the center-to-center distance between the columns is not uniform. This forces us to create non-uniform grids. As a result, for this
  • 11. 9 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 example, since there are no uniform grid spacing nor uniform story height, the ‘Custom Grid Spacing’ and ‘Custom Story Data’ options will be used. To create non-uniform grids: Access the ‘Define Grid Data’ window using either of the following methods: Method 1 From the window on figure 3, click on ‘Custom Grid Spacing’ > ‘Edit Grid…’ Method 2 Click the ‘Edit’ menu > ‘Edit Grid Data’ >’Edit Grid’ command to access the Coordinate Systems form. Then click the ‘Add New System’ button to display the ‘Coordinate System Definition’ window; click the ‘Edit Grid’ button. This method is particularly helpful if a grid system with cylindrical coordinate system is desired. Figure 4 In this window, the drop-down menu in the ‘Units’ box will be set to ‘KN-m’ as desired. However, a suitable radio button, ‘Ordinates’ or ‘Spacing’, from the ‘Display Grids as’ box should be selected. Choose ‘Ordinates’ if you want to enter the locations of the points defining the grid line using coordinates in the current units relative to the origin. Choose ‘Spacing’ if you want to enter the locations of the points defining the
  • 12. 10 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 grid line using spacing between the grid lines in the current units. In this example we will use the ‘Spacing’ option. As can be noted from the typical floor plan (first-tenth floor plan) of the building in this example, taking the bottom left corner as an origin, the spacings between the grid lines in x-direction are 2,5,4,7,5.5,3.5 and in y-direction are 3,6.5,5.5,6,3. Thus, these values will be entered in the ‘Spacing’ columns of ‘X Grid Data’ and ‘Y Grid Data’ boxes of the ‘Define Grid Data’ window shown in Fig. 4. For both cases, the last spacing value should be set to zero. The grid line can be a primary or secondary line. Click in the cell corresponding to ‘Line Type’ column to choose the appropriate option. Primary grid lines are intended to represent the main architectural grid lines of the building. Primary grid lines must have a grid line ID, which is displayed in a bubble on screen. Secondary grid lines are intended as temporary reference lines for modeling and do not have a bubble assigned to them for the grid ID. Use the ‘View menu’ > ‘Set Display’ Options command to collectively hide the secondary grid lines from view. Clicking ‘OK’ in the window shown in Fig 4 returns to the window shown in Fig. 3. After this the data regarding the story heights will be entered. For the building in this particular example, the story heights are non-uniform. Thus, the story dimensions will be entered through the ‘Custom Story Data’ option. For a normal G+10 building, there will be 12 stories including the foundation column. Therefore, enter this number in front of ‘Number of Stories’ after clicking on ‘Simple Story Data’ in the window shown in Fig. 3. To create non-uniform stories: From the window on figure 3, click on ‘Custom Story Data’ > ‘Edit Story Data…’ and the following ‘Story Data’ window will appear.
  • 13. 11 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 Figure 5 In the above window, the values shown in ‘Height’ column are the interstory height of the story level. It is the distance from the considered story level to the story level below. Therefore, in this column, change the value to 2 for ‘STORY1’ which is the foundation column and to 4 for ‘STORY2’ which is the ground floor. The rest stories will have a height of 3m. The ‘Master Story’ column is used to assign whether a given story is used as a template for other stories or not. This helps to replicate the drawing, assignment and selection of the given master story to other similar stories. In this example, we will have two master stories: the first floor (STORY2) and the sixth floor (STORY7) because the structural element sizes and the floor plan of the first floor through fifth floor are similar and the same is true from sixth floor to tenth floor. The ‘STORY2’ is master story to second through fifth floors while ‘STORY7’ is master story to seventh through tenth floors. In the ‘Similar To’ column, select the story level to which that particular story is similar. In this example, the roof floor (STORY12) and the ground floor (STORY1) are similar to none. But, ‘STORY3’ through ‘STORY6’ are similar to ‘STORY2’ while ‘STORY8’ through ‘STORY11’ are similar to ‘STORY7’. The ‘Splice Point’ and ‘Splice Height’ columns are used to specify if a splice occurs at this story level and to specify the splice height. The splice height is the distance from the bottom of the considered story up to the column splice location. The ‘Reset Selected Rows’ box provides edit boxes, drop-down lists, and display boxes along with Reset buttons for the various parameters in the spreadsheet in the
  • 14. 12 BY: ASAYE CHEMEDA (E-mail: asayechemeda@yahoo.com) AMBO UNIVERSITY CIVIL ENGINEERING DEPARTMENT 2016 upper portion of the from. Change one or more parameters shown and click the Reset button to change the data for all columns of that type. For example, assume that the spreadsheet area displays rows of data for STORY 4, STORY 3, STORY 2, STORY1 and BASE. Assume that the Height for Stories 4, 3, 2, and 1 are 10, 23, 12, and 12, respectively. If 15 is entered in the Height edit box in the Reset Selected Rows area and the Reset button is clicked, the Height for all stories will change to 15. Then click ‘OK’ on both windows in Fig. 5 and Fig. 3. This results in the following window. After clicking ‘OK’, if you want to modify the story height that you entered at a later time, click ‘Edit’ menu > ‘Edit Story Data’ > ‘Edit Story’. Figure 6 2.2. Define Materials Before defining the different materials which will be used for the design, it is better to set the design code other preferences which are appropriate for the design. To do this, click on ‘Options’ me
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