The users of the parametric tool will be Structural Engineering professionals. When designing a building, one of the first tasks asked of the structural engineer is to lay out the grid system of the structure. This then informs the locations and sizes of the columns and beams in the building. When designing the column sizes, many factors go into this decision including the load that is transferred from upper stories, the area loads applied on each floor and the tributary area that the column is responsible for. This tool will determine the axial load demand for a column in a building based on the structural grid layout of the building as well as the loads being transferred from the floors above and the area loads applied on that floor.
When working with the architect, the column layout is often iterative due to constantly changing geometries of the building meaning that this tool will allow the engineer to easily be able to evaluate how the loads on each column change with each changing design to see if changes need to be made to the column design. This will also allow design alternatives to be produced easily to be able to evaluate the changing loads in each column. The structural engineer will be responsible for changing the grid spacing in Revit but once this is complete, the workflow can compute the loads based on loading inputs.
The inputs that will be given to the program include the loads from the columns above (in pounds) in the form of an excel spreadsheet, the live load, the dead load, the roof live load, the snow load, the wind load, the earthquake load, the rain load, and the Revit input of the layout of the grid system. The loads (given in psf) will be in the form of sliders and combined using LRFD procedures to allow the user to change the loading inputs to see how these changes affect the column capacity. This program will assume the area load requirements are uniform across the entire floor. The grid system can also be changed by the user through the revit interface. The loads from the floors above can also be modified by the user by selecting different, previously output excel sheets to inform the loading demand.
The program will take the input of the grid and find the possible locations of the columns based on the intersection locations of the grid lines. These locations will be organized from the top left corner of the grid system then across the rows until reaching the bottom right corner of the grid system. The distance between each of the points and their closest relative will be found in both the x and y direction and each of these distances will be divided by two. Once this is done, the distances on the left and right of each grid intersection and the distance above and below the grid intersection that were calculated will be added together and will be the x-width and y-depth of the grid intersection point. These values will then be multiplied by each other to find the tributary area at each of the grid intersections. This tributary area will be multiplied by the LRFD combination of the area loads to find the total axial load that will be acting at the grid intersection. This load value will then be added to the value from the floors above (coming from the excel sheet) to find the total axial demand on the column in LRFD in pounds. This value will then be outputted into a spreadsheet for further processing and analysis if needed.
For the specific outputs this workflow will produce, the most important is the list of axial force requirements, in pounds, for each of the grid intersection points. This will be outputted in a spreadsheet as a column vector with the first value being the intersection at the top left corner of the grid and then following across the rows and moving down the columns until reaching the point at the bottom right corner. Each time the code is run, a new sheet can be created to ensure that all the information for a building is located in the same spreadsheet. In addition to this, the program will create lines in the Revit application window which symbolize where the different primary beams will be placed to better visualize the intersection where the columns will occur. This product will be viable for rectangular structures with horizontal and vertical grid lines but in future iterations could be modified to include structures with abnormal geometry and diagonal gridlines.
Two hours will be spent implementing this process by hand to produce axial loading results to verify code with as well as to verify the order of the steps that need to be completed for optimal results. Three hours will be spent implementing this process using dynamo and determining the specific nodes needed for the tool. One hour will be spent debugging the application to ensure it works as expected.
This tool is intended to help structural engineers calculate the axial force in pounds required in their columns based on the structural grid layout that has been established. This tool is intended to work for rectangular buildings with horizontal and vertical grid lines.
To use this tool, the user must draw and properly dimension their gridlines in Revit using the grid lines tool. They would then open dynamo and select the loading on their structure in pounds per square foot. The other inputs necessary will be the location of a spreadsheet which has all of the loads on the points from the floors above (in pounds) organized in the first column of the spreadsheet with the first entry being the top leftmost point continuing across the rows then down the columns of the structure until reaching the bottom rightmost point which will be the last entry in the column. They should then also input a file path for the location where they want the output of the run to be recorded. The places where inputs are necessary have been labelled in pink in the dynamo window but are also easily accessible using the dynamo player.
Once this is complete, the user should be able to press run and then the spreadsheet of axial force values in pounds will be recorded. The values are also displayed in dynamo in a watch node in the orange output group. The results are also displayed if using the dynamo player.
Figure 1. Excel Output
Figure 2. Revit Output
Figure 3. Dynamo Player Input
Figure 4. Dynamo Player Input
Figure 5. Dynamo Player Output
Figure 6. Dynamo Player Output
Figure 7. Dynamo Player Output
Figure 1. Screenshot of Full Code
Figure 2. Screenshot of Leftmost Code
Figure 3. Screenshot of Center Code
Figure 4. Screenshot of Rightmost Code