CE Advanced Structural Analysis. Lab 3 SAP2000 Beam and Frame Structures

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1 Department of Civil & Geological Engineering COLLEGE OF ENGINEERING CE Advanced Structural Analysis Lab 3 SAP2000 Beam and Frame Structures February 06 th, 2013 T.A: Ouafi Saha Professor: M. Boulfiza 1. Continuous Beam Units t, m, C Mat. Concrete Self Weight = 0 New features: Elaborated Loads, Local Axis Load pattern possibilities The most used, but not the only possibility, is the distributed load over frame elements. You can access it by selecting the frame element, then Menu Assign > Frame Loads > Distributed Select Load Name Other Possibility for Unit conv Force or Moment? Coordinate System and Direction Up to four definition points for the load Make sure to select the right option Possible way of combination At relative or absolute distance from node i Value of the load To used in case of uniform load over the whole frame element Local axes rotation For the local axis convention refer to the supplementary document, available on the class web site. The angular unit in SAP2000 is the degree. Let s try to rotate the right end support by 30 counter clockwise. 1

2 Select the extreme right node, Menu Assign > Joints > Local Axis Why -30? Displacement loading. Try to find and explore. In which kind of situation should we use it? Questions: - What are the extreme vertical deflections of the beam? - What are the reactions at each support? - Plot the internal forces and moment diagrams. - What about the axial force after support rotation? 2. Simple Frame with enhanced loading and different cross sections t 4t 3 t/m 2 t/m Units t, m, C Mat. Concrete Self Weight = 0 6 t.m l/2 P l/2 5t Sections in cm New features: Sections, Display, Local Axes Visualisation Section possibilities For the Tee section go to Menu Define > Section Properties > Frame Sections Click on Add New Property then Select type Steel and section Tee For Dimensions Name Convention refer to the supplementary document (available on the class web site). 2

3 Name Material, 4000 Psi for Concrete t3 =70 cm t2 =125 cm tf =15 cm tw =25 cm Quick preview of the Section Axis Visualization and Extruded View To change the visualisation default options, use Menu View, Set Display Options (Ctrl+E) Check Frame/Cables/Tendons Local Axes and Extrude View. Questions: - What values, distances, and directions should we use for the two intermediate concentrated loads? Check supplementary document. - Extract all results for point P (Displacement and internal forces). - Plot internal forces diagrams (N, T, and M) - What would happen if we forget to modify the concrete material? 3. Load Combination (ref. CE321) Dead Load = W D = 10 kn/m and P D = 60kN W D P D Live Load = L 1 = 15 kn/m Live Load = L 2 = 15 kn/m 5 m 2.5m New features: Load Combination, Output stations, Tabular Output. Units kn, m, C Material Concrete Section 300x650mm 2 Self-Weight included in Dead Load 3

4 Load Combination Use Menu Define with Load Patterns, Load Cases, and Load Combinations commands. We define first three load patterns D, L1, L2 as linear static. When assigning the loads, make sure to assign them to the appropriate load pattern. Define the load combinations. Consider the following combinations: 1.4 D 1.25 D L D L D (L 1 + L 2 ) 0.9 D L D L D (L 1 + L 2 ) Output stations By default SAP2000 uses 1 intermediate point (on top of the two end nodes) to show internal forces. When this is not sufficient, it is recommended to use more intermediate points. Five to nine output stations seems to be reasonable. Select the elements for which you want to modify the output station, and go to Menu Assign > Frame > Output Stations Tabular Output Graphic output is very friendly and useful, but sometimes difficult to analyse or to visualise. An exhaustive listing of the input and/or output is in these cases inevitable. To see the structure parameters in tabular form use Menu Display > Show Tables or Ctrl + T There are many functionalities to explore. 4

5 Questions - Which one, of the previous combinations, gives the Maximum Positive Moment and which one gives the Maximum Negative Moment? - Why is it important to consider the combination 0.9 D since it is smaller than 1.25 D? - Plot the linear envelope for these seven combinations. 4. Multi Story Building 3 m 3 m 4 m Units kn, m, C Mat. Steel Self Weight = 0 Beam S10x35 Column1 W10x45 Column2 W10x15 6 m 6 m 5 m 7 m New features: Modify Grid, Editing, Selection 5

6 Choose 2D Frames from the new model. Enter portal Frame Dimensions as shown below. For Section Properties click on button to access the sections dialogue box. Click on Import New Property then select material steel and click on I / Wide Flange. Then Select S10x35 for beams and select W10x45 for columns. Modify Grid according to our example Menu Define > Coordinate Systems/Grids click on Modify/Show System Change Values for coordinates X and Z Grid Data as required such as X (-12,-6,0,5,12) and Z (0,4,7,10) and check Glue to Grid Lines box. Another way to reach the same result is to use Menu Edit > Move and/or Replicate Selection - Selection of the basement nodes (difference between right and left) - Selection by Element Properties - Selection by Coordinate Specification Questions: - Find the position and the value of the Maximum Base Reactions. - Find the position and the value of the Maximum horizontal displacement. - What change would you suggest for the structure to be more balanced? - Do the same Analysis assuming the horizontal forces multiplied by two. Is it possible to implement the change in a single action? 6