Advanced 3-D Tutorial

Transcription

1 Advanced 3-D Tutorial Introduction To demonstrate some of the features of VisualAnalysis we have put together this advanced tutorial for you to use. This tutorial assumes that you have a basic knowledge of VisualAnalysis, and are familiar with 2-D modeling. It is highly recommended that you have been through the Visual Analysis Getting Started tutorial before using this tutorial. What You Will Learn This tutorial will teach you the following skills: 3-D Modeling Techniques Generating a Parametric Model Altering a Structure by Moving Nodes Using the View Manager to Navigate Complex Models Using Polar Coordinates Creating Curved Members Creating Member End Releases Saving Time with Cut & Paste Renaming Elements Creating and Editing Plate Elements Creating Custom Report Styles Reporting Results Graphically 18

2 The Structure This structure we have chosen for this tutorial is a steel moment frame with concrete floor slabs, masonry walls, and a glass atrium supported by glue laminated wood beams. The steel frame is made up of various sizes of W sections. Each level s floor slab as well as the roof is a 3000 psi concrete slab that is six inches thick. The walls are eightinch masonry, with a compressive strength of 2000 psi. Some design considerations have been left out of this example in order to simplify and shorten the tutorial. For instance, the connections in the moment frame should have the moment released with the use of shear walls. Also the connection between the wood glulams and the frame will transmit no moment and should have end releases there. In this tutorial we demonstrate the end release of the glulams but not the other connections. The dimensions of the model are shown on the picture below: < # ; = 19

3 Setting Up the Project The first step is to start a New Project in VisualAnalysis. The first two dialog boxes will allow you to setup the new project to be a three-dimensional space frame by checking the appropriate boxes. The third dialog box is called Generate Load Cases. It allows you to choose from UBC, ACI, and LRFD standard cases, custom cases you create or no cases at all. Select Use my custom template for Options, and select Dead, Snow, Wind & EQ Both Ways from the drop-down box. Click Next to continue. The fourth dialog box in the New Project wizard allows you to define the projects default units. Default units are used in new windows, dialog boxes when they are first opened, and in quick reports. You may use any units later, and you may change these at any time. To change the project units choose 0RGHO_(GLW_(GLW3URMHFW7\SH. The units displayed on the model or result windows are controlled by the units drop-down box, located at the bottom of the window. Accept the default units and click Finish to begin modeling your structure. Modeling the Structure There are many ways to create models in VisualAnalysis. You may import from an existing.dxf file (using )LOH_2SHQ) or you may sketch the model on the screen. For typical jobs VisualAnalysis will get you started quickly by generating a standard model. Moment frames are common in structural engineering. For this reason they have been included in the kinds of structures that VisualAnalysis can generate automatically. Choose 0RGHO_*HQHUDWH 6WDQGDUG«to start the Generate Standard Wizard. Select Moment Frame (Unbraced) from the list. Click Next to continue. 20

4 Select Point for the Origin Location and set the coordinates to (0,0,0). Click Next to continue. 7LS,I\RXDUH DGGLQJDIUDPHWRDQ H[LVWLQJRQH\RXFDQ DOLJQWKHQHZ DGGLWLRQSUHFLVHO\ ZLWKWKHFXUUHQW VWUXFWXUHE\VHWWLQJ WKHRULJLQKHUH The next dialog box allows you to establish the general size of your structure. Our basic frame is 50 ft long, 50 ft wide and has two bays in each direction. Set the X bay spacing and Y frame spacing to 25 ft. This will create a model with 50 ft sides. Our structure is 42 ft tall with three stories, or each story is 14 ft. Set the Story height to 14 ft. Click Next to continue. The General Mesh Gradation dialog box allows you to set the number of bays in each direction and the number of stories. Enter 2 for the number of Bays, M and for the number of Perpendicular bays, O. Enter 3 for the number of Stories, N. Click Finish to continue. You should now see the model shown at the top of the next page. 21

5 7LS <RXPD\KDYHWR URWDWHWKHYLHZLQJDQJOHWR PDNHWKHPRGHOORRNOLNH WKLV7RURWDWHWKHYLHZLQJ DQJOHKROG&75/DQGXVH DQDUURZNH\RUWKHOHWWHU 5RU7 The current model has two 25 ft bays along each axis, but the model that we truly wanted to create has one 30 ft bay and one 20 ft bay along the Z axis. To get the right bay spacing we will move the nodes of the interior column line. The first step is to select each of the nodes that need to be moved. The more complex a model is the more difficult it can become to select individual elements. The View Manager in VisualAnalysis can be used to make selection easier. The View Manager can be used to cut a slice out of the model space and view only it. To create the view slice you must specify a point to create the slice about. The point can be a node or a value on the axis perpendicular to the plane you choose to create. The depth of view is how deep your volume of view space will be. Once this volume is created you are shown only what fits inside those boundaries. The entire element must fit inside of the view slice in order for it to be shown. Choose 9LHZ_9LHZ0DQDJHU to activate the View Manager dialog box. Click on the Cut Plane/Grid tab at the top of the box. Select XY Elevation from the Type: drop-down box. Check the Z value button for Locate Planar Slice by:. Enter 25 ft for the Z value and 1 ft for the Depth of view in Z direction. Click OK to continue. 22

6 Your model should now look like the one at the right. Next, toggle the members off using 9LHZ _7RJJOH_7RJJOH0HPEHUV or click on the Modeling Toolbar. Select the remaining nodes by holding the Shift key while dragging a box around all of the nodes. Release the mouse button to select everything in the box. Choose 0RGHO_(GLW_1RGHV«to activate the Edit Nodes dialog box. Click the Move tab at the top of the box to display the Move Nodes Page. Check the Move each node a fixed distance button and enter 5 ft for the Move Z by: value. Click OK to continue. You should no longer be able to see any of your structure on the screen! Because you have moved all of the model elements outside of your view volume nothing will be displayed. Use the View Manager to change the depth of view in the cut plane to a value large enough to see the entire structure (1 million for example). Use the Toggle command to turn the members back on. You should now see your model with the uneven bay spacing along the Z axis, as shown below. Now would be a good time to save your work. 23

7 The next step in modeling our structure is to add the curved members to the model. To do this we will create a polar coordinate grid that has its origin at the center point of the quarter circles we need to add. Choose 9LHZ_9LHZ0DQDJHU or right click, and select the Cut Plane/Grid page. Select YZ Elevation from the Type: drop down box and check the X value button for Locate planar slice by. Enter O ft for the X value and enter 1 ft for the Depth of view in X direction. This will display the outside column line only, making it easier to create the curved member. Check Show Grid and Polar. Because the curved members are quarter circles with the same radius as the story height of the frame enter 14 ft in the Radius drop down box. Enter 9 deg in the Angle drop down box. This will place a grid point every 9 degrees, giving us ten points to draw members to. Finally, the side of the structure that the curved members will be placed on is not the side with the current origin. We must offset the origin of our polar grid, enter 50 ft in the Z drop- down box. Click OK to continue. Set your viewing angle to Y-Z Elev using the view orientation drop-down box at the bottom of the window on the Window Toolbar. Draw a member from the outside node on the first floor level to the first radial grid point on the left. Use the mouse to select this new member, choose (GLW _&RS\. Next choose (GLW_ 3DVWH6SHFLDO«, this will activate the Paste Special wizard. 24

8 Check the Using a circular pattern button. Click Next to continue. Check the The X axis button for Rotate parallel to. Check the Point button for Center of rotation and set the coordinates to (0,0,50). Click Next to continue. Enter 9 for Make copy or copies. Check the Total angle of rotation: button and enter 81 deg in the Angle: drop down box. Click Next to continue. As you can see nine more pieces have been added to the curved member. Use the View Manager to adjust the Depth of View so that the entire structure can be seen. Select all 10 elements of the curved member and choose (GLW_&RS\. Choose (GLW_3DVWH 6SHFLDO«, this will activate the Paste Special Wizard. 25

9 Check the Using a rectangular pattern button. Click Next to continue. Enter 2 and 25 ft, respectively, for Make copies in X, spaced at: Click Finish to continue. DO NOT CLICK TO UNSELECT THE NEW MEMBERS. The model should now look like the one below: 26

10 The reason for not unselecting the new curved members is that they must all be selected to rename them. Immediately after copying members in this fashion is the easiest time to rename them. Renaming is an extremely helpful tool when viewing reports, viewing the model with filters, or changing member sizes. Choose 0RGHO_ 5HQDPH«or click on the Modeling Toolbar to display the Rename dialog box. 7LS6RUWOLVWVOLNHWKLV E\FOLFNLQJRQWKHFROXPQ WLWOH&OLFNLWDJDLQWR UHYHUVHWKHVRUWRUGHU Select Selected Members from the Rename drop down box. Select X,Y,Z from the Order renaming by drop down box. Enter Curv in the Prefix names with box and set Starting number and Increment by to 1. Click OK to continue. The members of the standard frame were named automatically. &KRRVH0RGHO_(GLW_(GLW 0HPEHUV«or right-click to display the Group Edit Members dialog box. Select BM1 through BM8. Click OK to continue. As you can see, the eight members that were highlighted on the edit page have now been selected. To demonstrate the usefulness of renaming we will size the members. Go back to the Group Edit Members dialog box and select all of the BM members. Click on the Shape tab. Select AISC Shapes from the Category drop down box. Select W Shapes from the Group drop down box. Select W16x36 from the Section dialog box. Click OK to continue. 27

11 Repeat this process for the columns, girders, and curved members using the sections shown below. Member Column (COL) Girder (G) Curved Members (Curv) Section W12X79 W24X68 Western Species Glulam, GL5.125X15 It is necessary to change the behavior of some of the connections in our model to cause it to behave like the real world structure. For example, the connections between the glulam beams and the steel frame are not rigid connections. We will assume that there is essentially no moment transfer between the wood and the steel. To model this in VisualAnalysis is quite simple. Select the one element in each glulam member that connects to the moment frame. Choose 0RGHO_(GLW_(GLW0HPEHUV«to activate the Group Edit Members dialog, click on the Connections tab. Check the Strong Moment, Mz and the Weak moment, My buttons for Node 1. Click Next to continue. To show the releases on the model use the View Manager Filter page to turn on End Releases for members. The end releases are shown as small circles at the node where the release is. Node 1 and Node 2 are determined by the direction that they were drawn. 7LS 7KHVL]HDQGVKDSHRI PRVWREMHFWVOLNHWKHHQGUHOHDVH VKRZQFDQEHFKDQJHGWRPDNH WKHPHDVLHUIRU\RXWRXVHDQG VHH8VHWKH&XVWRPL]H 9LVXDO$QDO\VLVGLDORJER[WR PDNH9$ZRUNIRU\RX 28

12 Now that all of the framing has been modeled, we can add floor slabs and walls. To begin use the View Manager to view the first floor only. In the View Manger Cut Plane page set the type to ZX plan, Y value to 14 ft, and depth of view to 1ft, and click OK. Next set the model view to ZX Plan using the view orientation drop-down box at the bottom of the window on the Window Toolbar. Choose 0RGHO_'UDZ3ODWHV or click. Click and Drag from the node located above the global origin, labeled A in the figure below, (you will see that the cursor has changed from the small member to a square plate, this shows which drawing mode you are in). Place the cursor directly over the node labeled B and release the mouse button. Move the cursor to the node labeled C and click to attach the plate to that node. Finally, position the cursor over the node labeled D and click to attach. The convention is to draw plates in a counter-clockwise fashion from the lower left-hand corner. The direction that plates are drawn in establishes the local coordinate system (this affects the direction of loads and results for the plates). To view the local coordinates open the View Manager and select the Filter tab. D A C B Scroll down to Plates and check Local coordinate axes and Shrink. Click OK. You will now see the local X and Y axes for the plate, and you will notice that the plate is pulled away from the members, this is Shrink, it makes the model easier to work with. Drawing the plate as we have the local Z axes points up. Now draw in the other three plates on the first floor. 29

13 To change the properties of the floor slab, first select all of the plates. Choose 0RGHO_(GLW_(GLW3ODWHV«or click Edit Plates Dialog Box. on the Modeling Toolbar to display the Select the Properties Page and enter 6 in for Thickness. Now select the Material page. Change the Material Type dropdown box to Concrete and set Strength to 3 ksi. Click OK to continue. Use the Copy and Paste Special commands to create the slabs for the second story floor and roof. Use the same procedure that was used for the slabs to create 8, 2 ksi Masonry walls on all sides and all stories of the model (draw the wall plates so that the local Z axis points into the model). The model should look like the one below when you are finished: 30

14 This model appears to be an accurate representation of a moment frame with masonry walls and concrete floor slabs. This can be deceiving, however. The model we have created uses a single large plate element to model the floors and walls. The problem with this is that the plate elements are only connected to the supporting members at the nodes. In the real world the plates are in continuous contact with the supporting members. Modeling the structure as we have can cause larger deflections in some members than if they were modeled with intermediate connections. The walls may also be too stiff when modeled as a single element per bay. A final concern involves load path continuity. If a snow load were applied to the roof plates as shown above, the load would be transferred to the corners of the plate and directly down to the columns. The supporting beams would receive no load. To fix these problems the single plate will be split into smaller pieces, so that more nodes are provided to allow the real world connection to be more accurately modeled. The more each plate is split the more accurate the model becomes. However, this new model also has drawbacks. More elements require more time to analyze, this is particularly important with large models. Increasing the number of elements causes the model to be less manageable and the results more difficult to evaluate. Finally, this new model may not be refined enough. It may be necessary to split the elements even more (see the VisualAnalysis Users Guide for a discussion of How Many Plate Elements are Enough.) Select one of the largest roof plate elements and choose 0RGHO_6SOLW 3ODWHV«or click on the Modeling Toolbar to open the Split Plates dialog box. Sort the plate list by Area so that the 9000 ft^2 plates are all together at the top of the list. Select all of these plates. In the Divide Each Plate box enter 6 for Parts in x and 5 for Parts in y. Also check the Yes, split members too box. Click OK to continue. As you can see the plates have been split into 30 smaller plates. The reason for choosing to split the plate into six parts in the X direction and five in the Y direction is to try and keep the plate elements as square as possible. Long, skinny plate elements may give unrealistic results. It is better to break up large plates into small square plates to increase the accuracy of the model. Repeat the split plate procedure to split the remaining floor and wall plates into approximately square plates. 1RWH 6SOLWWLQJWKHSODWHVDQGPHPEHUVJHQHUDWHVQHZHOHPHQWVZLWKWKHVDPH SURSHUWLHVDVWKHRULJLQDOHOHPHQWVEXWWKH\DUHJLYHQGHIDXOWQDPLQJSUHIL[HV,Q WKLVH[DPSOHDOO%0HOHPHQWVDUHUHSODFHGZLWK0HOHPHQWV 31

15 The final step in modeling our structure is to define the support conditions of our columns and curved beams. Set the cut plane so that only the ground level nodes are visible and select all of the nodes. Choose 0RGHO_(GLW_(GLW 1RGHV«or click on the Modeling Toolbar to start the Edit Nodes dialog box. Select the Support page, and check the Support type button. Select Pinned from the drop down box. Click OK to continue. Modeling Steps Review Up to this point we have generated a parametric model and altered it, by moving the nodes of the interior columns, to create our basic framing. Our next step was to create a polar grid using the View Manager and add the elements to make up our curved glulam members. We used the Connections page of the Edit Member dialog box to release the moment at the connection between the glulam beams and the steel framing. With the framing complete we placed floor and wall plates on the structure, but to make our model a better, more accurate representation of the real world we split each of these plates into approximately square smaller elements. The final step in the modeling process was to define the support conditions for the columns of our model. We have also discussed the benefits of using the View Manager and Renaming to make your model easier to use. These tools will enable you to become more productive, and to better utilize the information VisualAnalysis gives you. Now we will add some loads to the structure, run the Analyze Wizard and discuss the many ways VisualAnalysis allows you to view and report your results. 32

16 Modeling the Loads Now that the modeling of the structure is complete we can begin to add some loads to the model. We will place snow loads on the structure so select the Full Snow Load service case from the drop down box at the bottom of the screen. We will apply a roof snow load of 25 psf to our structure. To begin, view only the plates by toggling off all of the members and nodes. Select the roof plate elements, then choose 0RGHO_&UHDWH _1HZ3ODWH/RDG«or right click, to start the New Plate Load dialog box. Check the Uniformly distributed button for Load Type: and enter ksf in the At node 1 drop-down box. Click OK to continue. The reason we are applying a negative (-) 25 psf to the roof plates is because of the local coordinate system created when we drew the plates using the counter-clockwise convention. Plate pressure loads are applied in the local Z direction. The local Z on all of our roof and floor plates are pointing up ( the same direction as the global Y). For our gravity loads to act in the proper direction we must add the negative (-) to our value. In this example we will also load the upper five elements of the curved members. For simplicity in this example we will apply a constant line load to the elements. 25 psf over 12.5 ft gives a line load of plf on the outside elements. The inside elements will receive twice that load. Select the upper five elements on both outside curved members, choose 0RGHO_&UHDWH_1HZ0HPEHU/RDG«or right click, to start the New Member Load dialog box. 33

17 Check the Uniformly distributed and the Global Direction button, choose Force Y from the Direction drop-down box. Because snow loading is applied to the projected area of the member, check the On projected member lenth button. Click the Magnitude page to continue. Because the direction of the load is controlled by the coordinate system, these loads must also be negative. Enter K/ft in the Force drop-down box and check the Full member length check box. Click OK to continue. Repeat the New Member Load process to place a load of 625 plf on the projected length of the upper five elements of the center curved member. During an actual design you will have many different kinds of loads to apply. To apply all of these different loads and to keep the different load types separate simply switch to a different load case. In this example we started with the default custom load case template which generated six different cases. To add loads to these click on the load case drop down box at the bottom of the window and select the appropriate case for the load you would like to apply. If you choose to not have any load cases generated initially you can create your own. To create a new service case choose 0RGHO_&UHDWH_1HZ 6HUYLFH&DVH or right click and choose 1HZ6HUYLFH&DVH from the model view popup menu. For more information about service cases see your VisualAnalysis User s Guide. 34

18 Analyzing the Structure To begin the analysis choose 5HVXOWV_ $QDO\]H:L]DUG«to start the Analysis Wizard. Check the Static button for Analysis Type, and be sure that the Minimize Bandwidth option is checked. Click Next to continue. Check First order for the Static Analysis Type. Click Next to continue. Choose only Full Snow Load from the list and click Finish to continue. 35

19 The Analysis Progress window lists the steps VisualAnalysis goes through to get results for the structure. Under normal circumstances this window pops up at the start of the analysis and goes away when the analysis is over. However, if a problem occurs during the analysis this window will stay active and is a useful tool in detecting the cause of any problems. Do not be alarmed if the analysis takes several minutes. We have created a large model with many plates and members. When the analysis is complete the Results window will be displayed for each load case that was selected in the analysis wizard. This window shows the deflected shape of the structure. The result window for the example structure should look something like the one below: (only members are displayed in this picture.) Try toggling the nodes and plates on to view the full model results. As you will see it is very important to use the View Manager to efficiently evaluate your results. 36

20 Reporting Results There are several ways to generate reports of your analysis results. You can use the Quick Report, or you can use the Report Wizard to create a report based on a predefined style, modify one of the predefined styles, or start from scratch and create a custom report. First we will create a simple custom report and save it as a predefined style. Choose 9LHZ_ 5HSRUW:L]DUG«or right-click to start the Report Wizard. Check the Create a custom-made report from scratch button. Click Next to continue. Select Member Internal Forces, Member Internal Stresses, and Member Local Displacements from the Available items box and click to add them to the Reported items. Click Next to continue. You can use the Table drop down box to choose which table to select items for. For each of the three tables in our report a different set of available items can be chosen. Choose all three tables, one at a time, and view the list of available and selected items for each. Use the default selected items and click Next to continue. 37

21 Check the Detailed table of all results button for Result Table Type: and enter 4 for the Number of member result sections for each result table. Note: You must highlight each result table in the Select result table to edit: box and set the options separately for each. Click Next to continue. The Column Options page allows you to customize the format and units of the reported information. Use the drop-down box at the top of the window to switch between tables, use the Select column to edit box to choose individual columns out of the table, and finally set the properties for each column using the buttons and dropdown boxes in the Column Properties box. The example shown in the picture is for the Member Internal Stresses table, fx column, and the units chosen for this item are ksi. Use this window to setup the following properties: Table Column Sort Units Width Decimal All Member Ascending N/A 8 N/A All Load Case Ascending N/A 15 N/A All Offset Ascending )W 7 4 Internal Forces Forces Ascending K 7 4 Internal Forces Moments Ascending K-ft 7 4 Internal Stresses Stresses Ascending Ksi 7 4 Local Displacements Displacements Ascending In 7 4 Click Next to continue. 38

22 Check the Named objects button and enter BM in the box below. Click Next to continue. Check the Select from the load cases below button and choose the Full Snow Load case from the list. Click Finish to continue. A report window will be generated that looks similar to the one below: As you scroll down the report window you will notice that some of the results are displayed in boldface type. These are the extreme values for that column. To save this beam report as a custom style choose 2SWLRQV_6DYH5HSRUW6W\OH«or right click, to open the Save Report Style window. 39

23 Enter a name and Click OK if you wish to save this style, if not click Cancel. Styles can be changed or deleted using WKH2SWLRQV _(GLW5HSRUW 6W\OHV command. It is also possible to report results for selected objects on the screen. Use the View Manager to view the interior row of columns that lie parallel to the YZ plane. Select all of the elements of the column that is on the X-axis, with the mouse and choose 9LHZ_4XLFN 5HSRUW or right click. Place the cursor in the Member Internal Forces table header area and double click the left mouse button. This will open the Table Properties dialog box, similar to the box used to create a custom report. Click on the Result Table Options tab. In the Result Table Type box check the Extreme column results only button. Resize the Report Window and the Results window and place them so that they both can be seen at one time. Click the Result window on the Windows Title Bar to reactivate it. If you click anywhere in the modeling area you will unselect the members you have selected. Select the elements of the interior column by holding the Ctrl key while clicking on the members. Click back on the Report window. You should see that the report has updated to include the newly selected members. The table now shows the maximum and minimum values for all of the selected elements. 40

24 Graphically Reporting Results VisualAnalysis offers another way to see the results of the analysis. The forces and stresses in the elements can be displayed graphically. There are several ways to display the results. The first way is through individual member graphs. Select a roof member that has deflected significantly. Choose 9LHZ_1HZ:LQGRZ_0HPEHU*UDSK or right click. Your graph may not look exactly like this one depending on the specific member you picked. This is only the top half of what will be displayed in the new window. For 3-D models the default display for the member graph shows the Shear Y & Z, Moment Y & Z, and Displacement Y & Z. To include Axial Force, Torsion, or to change the number of decimal places use the View Manager. The second method allows you to display the forces or stresses on the result model itself. From the Result window open the View Manager. Under Members check the Stresses button, click on the plus box to expand the list, and check the Fb+y, bending stress button. Continue to scroll down the list until the Window options are shown. Uncheck the Displaced shape, Factor button. Click OK to continue. The roof members of the structure should display this type of bending stress diagram. If you select members now, the max and min stress for the selected members will be displayed in the legend box as well.results can be reported graphically for plate elements as well. Using the View Manager in a model window select all of the roof plates 41

25 and rename them ROOF. Return to the result window and open the filter page of the View Manager. Click to the right of the Filter: and type ROOF. Scroll down and check the Top (+z) surface stress button. Expand the list and also check the Max. principle sigma button. Click OK to continue. ;=3ODQ <=(OHYDWLRQ This displays the increasing levels of stress in the plates by color. Blue is lower, red is higher relative to each other. This is similar to the unity check used in the Visual Design addition to Visual Analysis. It does not indicate how good or bad these stress levels may be. 42

26 Launch Point Hopefully, this tutorial has given you some insights into the design and operation of this VisualAnalysis. There is obviously much more to learn and explore! Often, the best way to learn is by experimenting. Please make use of the F1 key, the on-line help system and the User s Guide. Included with VisualAnalysis are a number of example problems that you can try to recreate, or simply play with to discover how the program works. The examples are discussed in the User's Guide. 43