Civil Engineering Concept Design — Good Foundations Engineering Tutors

Engineering degrees typically place a strong emphasis on detailed design and theoretical aspects. Students often find themselves immersed in the intricacies of designing specific elements like concrete beams or steel columns. This focus aligns well with many engineering students who thrive on tackling detailed problems and methodically developing solutions through mathematical processes.

However, the introduction of concept design usually occurs later in an undergraduate engineering program. The delay in introducing concept design is partly due to the necessity of first establishing a solid foundation in fundamental engineering principles. A deep understanding of these basics is crucial for any effective concept design process.

After spending a significant amount of time on detailed design, students might find it challenging to transition to the broader perspective required for concept design. This shift demands a different approach to problem-solving. In concept design, there are often multiple viable paths to a solution, requiring a broader understanding of materials and engineering principles. Unlike detailed design, where the focus is often on mathematics and step-by-step calculations, concept design calls for more holistic thinking and the ability to integrate various engineering concepts.

In concept design, the emphasis shifts from precise calculations to exploring different design options, considering various materials, and understanding their implications on the overall project. This approach requires students to think more creatively and expansively, often considering factors like sustainability, cost-effectiveness, and practicality.

It's important for engineering curricula to balance both detailed and concept design teachings. This balance ensures that students are not only adept at crunching numbers and performing calculations but also at seeing the bigger picture, which is essential in real-world engineering projects where design decisions impact broader aspects like environmental sustainability, user experience, and economic feasibility.

Incorporating project-based learning, where students work on real-life problems or simulations, can be an effective way to introduce concept design earlier in the curriculum. This approach allows students to apply their detailed design skills in broader project contexts, thus bridging the gap between detailed and concept design thinking.

A quote from the famous engineer Ove Arup neatly summarises concept design:

“Engineering problems are under-defined, there are many solutions, good, bad and indifferent. The art is to arrive at a good solution. This is a creative activity, involving imagination, intuition and deliberate choice.”

It is the creativity in concept design that makes in a favourite task of many practicing engineers.

This note aims to introduce the engineering student to concept design and provide some useful resources to aid in their concept design projects.

Concept Design in Practice

Concept design is required in the early stages of engineering projects to quickly develop multiple possible solutions. This is often done in collaboration with other disciplines (for example on a building project the civil engineer will work with the architect and services engineers). A range of viable solutions can then be presented to the client for discussion and refinement before selection to proceed to detailed design. At this stage a ‘basis of structural design’ document is also normally produced that summarises key project details such as loading, durability, design life, fire resistance and serviceability criteria.

This process is mimicked in the Institution of Structural Engineers (IstructE) chartered membership examination where in section 1 the exam asks for 2 viable solutions to be developed to a concept design level. One design is then chosen as superior and developed further in section 2 of the exam.

Like any skill, concept design will become more familiar with practice. At engineering consultancies, concept design is normally undertaken by senior engineers with experience. A young engineer’s exposure to concept design may initially be limited to attending early design team meetings.

To become proficient at concept design requires a good grasp of the fundamentals of civil engineering – material science (steel, concrete, timber) and mechanics. A broad understanding of construction and the economics of construction will also enable the engineer to develop viable and economic concept designs.

Concept Design at University

In the later years of an undergraduate degree students might be tasked with a design project that involves an element of concept design. A typical project will give a brief for a particular building and ask for two possible solutions to be developed – somewhat similar to the task asked for in the IstructE Chartered Members Examination (but likely less challenging and with less detail required).

To complete these projects the student will need to select an appropriate structural form and material. Following this preliminary element sizes can be found using span/depth ratios.

Choosing structural form and material

An understanding of appropriate structural form is perhaps the more difficult exercise for an undergraduate student. In particular, the issue of building stability is often less well understood by students who have spent most of their time designing vertical load carrying elements.

The following items need to be addressed:

Good resources to address all of these items are listed below.

Element size estimation

When the form and material is chosen, preliminary element sizing can be carried out using simple span-depth ratios. For example – sizing a steel primary beam spanning 10m.

Steel primary beam

typical span of 4-12m

beam depth of L/12.5.

beam depth = 1000/12.5 = 800mm

The span depth tables are also useful when we ae deciding on structural form – it can be seen from the above that trying for a 15m primary beam span isnt feasible in steel construction.

Resources for concept design

As well as the material given to you in your course, the following are useful resources for concept design. Most of the below are free design guides available online.

Steel

Steel Construction Info Website

www.steelconstruction.info/concept_design

Steel Building Design Guide

www.steelconstruction.info/eurocode_design_guides

Concrete

Design guides for concrete frames, tall buildings, multi storey carparks and more

www.concretecentre.com/publications

Foundations and Stability

The IstructE essential knowledge series is available for free to IStructE graduate and student members.

IStructE Essential Knowledge Series - Text 16 - Stability

IStructE Essential Knowledge Series - Text 19 - Ground Engineering Part 2