Thrifty Seismic - 2 Units
Thrifty Seismic is a tool that allows users to quickly evaluate different tower heights and geometries for Economic, Energy Efficiency and Foundation Loading (Including Seismic Loading). Since square buildings are so 1900s, this tool is meant to be used for towers with circular or elliptical floor shape areas that can be uniform in height or taper in between the floor and the top. The following toll will allow for a quick analysis in order to deem how viable the project is in an economic way, obtain energy efficiency parameters and Foundation Loading to decide on the viability of the project given certain soil conditions.
Demo
Input
R1 = Radius in ft
R2/R2 Proportion = If tower is circular, leave at 1. If an ellipse is desired, change to desired proportion
Height at Contraction Proportion = Similar to a sand watch, the building can taper in height at a desired proportion with relation to the total height
Contraction Radius Proportion = How much will the building contract in floor plan in proportion to the base
Construction Cost/Rent at base = Cost and Rent at base level
Additional Construction Cost/Rent Per Level = Given the Construction/Rent at the base, how much will it increase in height per additional level
Discount Rate and Period = Used for Net Present Value Calculation
Floor Load = Floor Load to consider in the analysis
Sds - Spectral Accelerations at Short Period = Given the location of the building, we can calculate a Sds. This will be useful to calculate seismic loads
Geometry
Given the previous parameters, the following shape was generated. We can observe the elliptical shape and the taper at 3/4 of the height:
Output
No project has ever started with a projected negative cashflow. It is important to calculate a net present value given the projected initial investment and an expected payment. In this case, the payment is in the form of an annuity, similar to bond payments.
Then basic outputs such as Floor Area, Volume and Surface Area are provided.
Followed by Surface Area / Volume Ratio, which is related to energy efficiency in buildings (and many more things in real life). The smaller this ratio, the easier it will be to thermoregulate our building.
Finally, Axial Load, Seismic Base Shears and Seismic Overturning Moments are provided. This will help with Foundation prices estimation and feasibility. It important to note that in this case, the calculation was done by an Elastic Linear Procedure assuming loads were uniform through height. This is a conservative estimation. In addition, the spectral acceleration was taken as the one at short periods, which is usually the highest and valid for small and medium height buildings. For tall buildings, this tool will be very conservative and should be complemented with a more refined analysis.
Dynamo Logic
The Dynamo Node has the following Input Logic:
Basic Curves were created to assemble our geometry
The solid and the surface are generated
Basic parameters are calculated
Floor areas are calculated
Initial Investment and Yearly Income are calculated. Then, with the help of my previously created custom node, we calculate the Net Present Value given the costs, revenues and discount rates and years. In this case, the revenue is in the form of an annuity, similar to bond payments
Finally, Axial Loads due to dead load, Seismic Base Shears and Overturning Moments are calculated
Finally, the output is reported:
It is important to note that the user can also take advantage of the Generative Design Toolbox and optimize the design given various parameters. In this case, we will vary the proportions of the ellipses and the number of floors in the structure in order to maximize the Net Present Value and minimize the Seismic Overturning Moment Potential
We can observe that Net Present Value (Y-Axis) seems to reach a limit while the Seismic Overturning Moment Potential keeps increasing. This is given an increase in the number of floors while the R2/R1 proportion seems to stabilize. In early stages of design, soil properties are one of the few variables we may know, and we may want to limit loads on foundation systems given the type of soil profile. As we can see, the results follow two lines. At first, our increase in NPV is linear with the Seismic Overturning Moment. In the second line, this has a lower slope and a parabolic behavior which means that while we increase the risk of high FDN loads and Soil Collapse, our return in investment is diminished. Given our risk tolerance, we will take a design decision