Professional and Career Topics

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

For me this is an every day thing. I work in house for a contractor and only running one case to meet scheduling demands, or simplify fabrication/installation is often a higher mandate than value engineering the materials costs. One of the bigger jobs I am working on right now involves steel tubes supported at their ends by embeds in the columns. Some of the steel has long spans with flood impact loading and some of it is a couple feet long and supporting nearly nothing; despite drastically different load cases, these use the same steel & embed detailing because it reduced a lot of timelines and cost despite the additional material. 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

This is a really important question, and I think that since we design to a code we think of additional capacity as "over" design.

Because codes are a minimum, additional capacity is "right" design.  Not providing the extra capacity and having the pipes clog is a design failure, therefore following the code would be under designing the system.  Designing a hollow sidewalk for pedestrians in a location where a truck could drive on it meets the code for the sidewalk but is under designed for the likely load, even if the code does not mention it.

On the other hand, sometimes additional capacity is not to avoid failure but to save time or money in design or labor.  But is this over design?  There is a case to be made that it is not since engineering also takes cost into account.  But others might see it differently.

Thinking about these questions is what makes us better engineers and gives us flexibility in how we design and build our projects.

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

Hi Sarah

As a young engineer I made the mistake to leave too little margin in prelimimary dimensioning to accommodate additional loads emerging lateron.

Only with professional experience I learned about the value of robustness that economic design often means to chose the same size for a group of members with similar degree of utilization for the ease of fabrication and guarding against confusion during assembly.

As Professor Alain Harris at Imperial College stated: Shouldn't the sail-like concrete roof structure of the Sydney Opera House better have been designed with the same curvature in order to allow reuse of the shuttering?

This is a really important question, and I think that since we design to a code we think of additional capacity as "over" design.

Because codes are a minimum, additional capacity is "right" design.  Not providing the extra capacity and having the pipes clog is a design failure, therefore following the code would be under designing the system.  Designing a hollow sidewalk for pedestrians in a location where a truck could drive on it meets the code for the sidewalk but is under designed for the likely load, even if the code does not mention it.

On the other hand, sometimes additional capacity is not to avoid failure but to save time or money in design or labor.  But is this over design?  There is a case to be made that it is not since engineering also takes cost into account.  But others might see it differently.

Thinking about these questions is what makes us better engineers and gives us flexibility in how we design and build our projects.

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

This is a really important question, and I think that since we design to a code we think of additional capacity as "over" design.

Because codes are a minimum, additional capacity is "right" design.  Not providing the extra capacity and having the pipes clog is a design failure, therefore following the code would be under designing the system.  Designing a hollow sidewalk for pedestrians in a location where a truck could drive on it meets the code for the sidewalk but is under designed for the likely load, even if the code does not mention it.

On the other hand, sometimes additional capacity is not to avoid failure but to save time or money in design or labor.  But is this over design?  There is a case to be made that it is not since engineering also takes cost into account.  But others might see it differently.

Thinking about these questions is what makes us better engineers and gives us flexibility in how we design and build our projects.

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

Great topic Christopher. I wouldn't say overdesign is the correct design. It can rather be termed as the traditional or conventional method in design processes. One important reason for this – is the lack of surety or absolute confidence in design factors – the uncertainty. As an engineering project is perceived to ride on an upward trend in risk scale – so does the necessity of increasing the embedment of layers of redundancy (or Factor-of-Safety) in designs.

In probabilistic concept of design – this method is known as the Level – 0 or deterministic design. On coastal engineering, here are something from Uncertainty Propagation in Wave Loadings:

In engineering design processes, the traditional method of accounting for uncertainty is done simply by including some redundancy in the system – by the so-called factors of safety – conspicuously described and/or inconspicuously embedded in some practices (for example, using maximum load and minimum strength; and summation of different loads together although they may not occur simultaneously). Further elaboration on coastal design processes can be found in Oumeraci et al (1999), Burcharth (2003) and Pilarczyk (2003). They scaled the processes of design as: Level 0 – deterministic approach; Level I – quasi-probabilistic approach; Level II – approximate probabilistic approach; and Level III – fully probabilistic approach. In the Level 0 approach, parameter uncertainties are not accounted for, instead experience and professional judgment are relied upon to implant redundancy. This practice as a way of developing confidence or assurance – represents in reality – a process of introducing another layer of uncertainty – partly because of heuristics associated with judgments. Or in another interpretation, it amounts to over-designing structure elements at the expense of high cost. For the other three Levels, a load-strength reliability function is defined in different scales to account for parameter uncertainties.

Dilip

---------

Dr. Dilip K Barua, Ph.D

Website Links and Profile

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

Design structure eccentric it may work a lots of calculation has been done if even it's over design. Our human software could be doing well with the rest. 

Alex Thomas MASCE FIE PE MIGS 

Thudianplackal C/0 Bethel Koch Ernakulam Kerala India 

Great topic Christopher. I wouldn't say overdesign is the correct design. It can rather be termed as the traditional or conventional method in design processes. One important reason for this – is the lack of surety or absolute confidence in design factors – the uncertainty. As an engineering project is perceived to ride on an upward trend in risk scale – so does the necessity of increasing the embedment of layers of redundancy (or Factor-of-Safety) in designs.

In probabilistic concept of design – this method is known as the Level – 0 or deterministic design. On coastal engineering, here are something from Uncertainty Propagation in Wave Loadings:

In engineering design processes, the traditional method of accounting for uncertainty is done simply by including some redundancy in the system – by the so-called factors of safety – conspicuously described and/or inconspicuously embedded in some practices (for example, using maximum load and minimum strength; and summation of different loads together although they may not occur simultaneously). Further elaboration on coastal design processes can be found in Oumeraci et al (1999), Burcharth (2003) and Pilarczyk (2003). They scaled the processes of design as: Level 0 – deterministic approach; Level I – quasi-probabilistic approach; Level II – approximate probabilistic approach; and Level III – fully probabilistic approach. In the Level 0 approach, parameter uncertainties are not accounted for, instead experience and professional judgment are relied upon to implant redundancy. This practice as a way of developing confidence or assurance – represents in reality – a process of introducing another layer of uncertainty – partly because of heuristics associated with judgments. Or in another interpretation, it amounts to over-designing structure elements at the expense of high cost. For the other three Levels, a load-strength reliability function is defined in different scales to account for parameter uncertainties.

Dilip

---------

Dr. Dilip K Barua, Ph.D

Website Links and Profile

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

When ductility matters, 6 #12 mm replaced by 4 #16 but it had it's on drawback. When 5 #20 replayed by 6 #16 it shows failure even than same alignment and patterns for beams and columns 

Alex Thomas MASCE FIE PE 

Thudianplackal C/0

Bethel Koch Ernakulam Kerala India 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

Reading the comments reminds me that water-related design an be very different than structure-related design. It seems that water design is much less reliant on codes. Am I mistaken?

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

Bill – Mc, I don't think you are mistaken. As intuitively obvious as they are – there are many reasons why design processes – pose different problems depending on where they are sited. For example, river water-front, coastal water-front and in-water structural planning and designs – must be approached differently than their cousins in other areas.

Appropriate and applicable Standards and Codes are always there irrespective of where the structure is located. An engineer cannot circumvent them.

In terms of Coastal Civil Engineering (CCE) works – one needs to account for different Force Fields in a Coastal System that dictate appropriate design approaches. Further, hydrodynamic interactions with the structure – like the types of Wave Structure Interactions & Scour – must be accounted for.

Here are what have been highlighted in the Civil Engineering on our Seashore:

. . . Coastal structures are not like a tall building standing on a dry land – and they should not be treated as such. Because of their exposed location in water or at the water-front, they continuously come under attack by the dynamic and uncertain metocean forcing – from regular to extreme. They must withstand different aspects of the force fields - during construction and operational lifetime, as well as face the consequences of uncertain fluid-structure interaction processes, and have to cause minimum impacts on the surrounding environments.
Therefore the role of a coastal engineer is very crucial – not only in the establishment of design and operational conditions and criteria, but also during the process of planning, design and construction. Lack of effective coordination, cooperation and concordance among various disciplines – or perhaps in not recognizing the proper roles required of certain disciplines – could lead to earning bad reputation, and to risks of incurring serious economic losses . . .

Dilip
---------

Dr. Dilip K Barua, Ph.D

Website Links and Profile

Reading the comments reminds me that water-related design an be very different than structure-related design. It seems that water design is much less reliant on codes. Am I mistaken?

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time". 

We all recognize that some level of overdesign is often necessary due to the many uncertainties inherent in whichever flavor of design process you are involved in -think sizing for peak flows, factoring in future loads, or building in safety margins. But overdesign isn't always about uncertainty. Sometimes it's driven by practicality. For example, a contractor might have materials on hand that exceed the spec, but using them avoids delays or otherwise reduces costs overall. Have you encountered other situations where overdesign was chosen for practicality rather than uncertainty? 

I can go first:

I was once asked to size a small pipe by a colleague. I asked another colleague to review my work, and explained that I was torn between pipes of two different sizes. My colleague reviewed my work and then simply said "either of these will probably meet the expected flow, but realistically anything less than the larger one is likely going to clog all the time".