4 Design Methods Used by Structural Engineers
When a structural engineer sits down to design a structure, there are a number of possible tools available. These vary based on budget, time, company processes and personal preferences. In this article, we examine these methods and address the pros and cons of each. Let's explore the processes that engineers use for design with respect to five areas: cost, work speed, updates, margin of error, and analysis.
1. Hand Calculations
Hand calculations are the cornerstone of engineering: they force users to apply logic and exercise their mental capacity. Regardless of your other design method, a quick double check of your work by hand will help you be confident in your results and keep your engineering skills in tune. .
There are a number of obvious limitations to hand calculations, as it is generally the slowest of the possible methods. It results in a thorough and well-considered report, but can mean the member is over-engineered due to the difficulty of iterating on a design. By relying on this approach alone, you are susceptible to inevitable human error. Additionally, if assumptions are made about the model to streamline the hand calculations, this can lead to inaccurate results.
2. In-House Spreadsheets
Excel is a valuable tool used by engineers to produce a repeatable outcome. Macros are also relatively easy for engineers to pick up as they typically have an analytical and logical mind. It is an extremely cost effective solution, as the only 'cost' is the time spent by the engineer or IT department to build the solution.
The limitations include a high upfront time and cost, as the engineers actually build the tools themselves. It also requires upkeep and updates that must be managed in-house, including revisions to keep up with current codes, load combinations, and requirements.
Freeware has the obvious benefit of being free. Free Design Software can be a great way to calculate your designs once you can roughly estimate the forces applied to your members. Many offer the desired reports in a well documented format and, provided your input is correct, is an efficient way of finishing the design process post-analysis.
However, there is some disconnect between analysis and design: many of the forces, members, lengths and connectivities must be manually input. This can slow down your design process and prevent iteration for optimal design, but is still faster than the first two options. Since this is free software, there are occasional delays in producing the most up to date versions of the program. However, this is not the case for SkyCiv Free Structural Software which is updated immediately with no downloads required.
4. Full Analysis & Design Software
A powerful Structural Analysis and Design Software is the most effective and fastest method of designing your structure. It helps engineers speed up the process exponentially: the user can model and design each of the members within one workflow and all internal forces, members, materials and section properties are automatically pulled from the model. Although a powerful software, it still requires a skilled operator to use it to its full potential.
The only setback of this method is the lack of accessibility, as these programs are fairly expensive and require lifetime licenses. However, with SkyCiv's cost-effective pricing, this is no longer an issue. Additionally, some of these types of software require regular costs and updates to keep the design codes up-to-date, although not the case with SkyCiv as updates will be pushed automatically to the user.
I would recommend using a combination of any two processes, particularly if it's on a critical member or structure. It is essential to choose the process that best meets your design needs as an engineer. Some might just need the capacity of single members to which hand calculations would suffice, whereas others may need to run analysis and design on multi-storey structures that will require powerful analysis software.
CEO and Co-Founder of SkyCiv
BEng (Civil), BCom