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Software programs for structural engineers continue to escalate in complexity as we continue to become increasingly reliant on such tools to increase accuracy in our analysis and efficiency during the design process. To solve these complex problems efficiently, and to gain a more in-depth understanding of the elements being analyzed, a greater number of structural engineers are using Finite Element Analysis (FEA). Of course, each of the different FEA programs have their own idiosyncrasies which require us to pay close attention when we move from one program to another.
Read more here: Finite Element Analysis for Masonry Design
When designing a masonry wall with a large concentrated load acting on it, one might be tempted to build a concrete pilaster to resist the load. After all, concrete is stronger than masonry, so more load can be supported by the concrete pilaster than a similarly-sized masonry pilaster. But is that really worth it? Let us take a look at a couple of typical examples and see how they compare.
Read more here: Masonry Pilasters
Most times when a structural engineer designs a masonry wall, it is designed as running bond. This construction method yields good structural integrity with overlapped blocks. Sometimes, however, a stack bond wall might be requested for aesthetic reasons. A masonry wall constructed with stack bond can have structural capacity similar to running bond, provided reinforcing requirements are met.
Read more here: Stack Bond from a Structural Engineer’s Perspective
In recent years, there has been a renewed interest in using reinforced masonry lintels instead of steel lintels.
Read more here: Masonry versus Steel Lintel
When designing walls with concrete masonry units (CMU), one aspect that needs to be considered is the location of control joints, as this can have an effect on the cost of the project. Masonry walls, like concrete walls, will shrink after placement due to moisture content and temperature changes. Control joints provide a plane of weakness where shrinkage cracks can form in a controlled manner. The number and location of control joints can have a considerable effect on the capacity of the walls.
Read more here: Why Are Masonry Control Joint Locations Significant
When designing a typical low-rise building, a thought that can sometimes enter an engineer’s mind is that masonry walls are too heavy and will lead to larger foundations. A lighter wall would need smaller and less expensive foundations, right? This is not necessarily the case, and this way of thinking can sometimes lead to inefficient designs.
Read more here: Wall Weight Myth
Hidden costs in WI buildings
Two major cost items are going unnoticed in the design and construction of buildings here in WI. The costs of not having special inspections and low bid engineering are starting to really impact the cost of buildings.
Last month, I covered the cost of not having special inspections, this month I will be covering the cost of low bid engineering.
How did we get here? Structural engineering is becoming a commodity, we have been speculating that this would happen, but most didn’t think it would happen so quickly. The struggling economy is making owners/contractors desperate to save costs in all areas, including design. The value for a highly qualified structural engineer is diminishing and likely only reserved for extremely difficult designs; for example, taller than usual buildings, although what quantifies as tall is getting higher. In difficult building designs, owner and architectural team respect higher cost to get higher quality design. But, this percentage of buildings is getting smaller and smaller, and the rest of the designs are treated more like commodities.
By doing this, the owners/contractors are saying that the cost of design is paramount, since all designs are going to be equal. Let me say it a different way, regardless of who designs the building, the building will be the same cost, so we need to focus on selecting the engineer with the lowest fees. Even though in most cases, the design fees are less than 1% of buildings final cost. Saving a fraction of that 1%, is more important than making sure the 99% is the safest and most economical (see last months article on special inspection).
In designs that I have reviewed, where low bid has been selected for structural engineering, I believe buildings are being over designed. And there really aren’t any checks in place to monitor what one engineers design would have cost versus another engineers design. Can this really be true, are owner/contractors so concerned with saving initial design costs that they are selecting the engineer with the lowest fees even when 1% over design will result in a more expensive building. Saving any percentage, even up to getting the design for free, will end up costing owners contractors more in the end.
This coupled with the unchecked construction world in WI due to not having special inspections, is doubly bad … Costing more and less safe. How did we get to this point?
Hidden costs in Wisconsin buildings
Two major cost items are going unnoticed in the design and construction of buildings here inWisconsin. The costs of not having Special Inspections and low bid engineering are starting to really impact the cost of buildings.
This month I am covering the cost of not having special inspections and next month I will tackle the cost of low bid engineering.
State of Wisconsin elects to omit IBC code provisions for Special Inspection
When I learned 12 years ago that Wisconsin was going to adopt the 2000 International Building Code (IBC), but was to omit the chapter on special inspections, the first question asked myself was, “WHY? Why would a state chose to omit a chapter of a nationally recognized building code? What is so different in Wisconsin that we choose to omit the largest quality control program in the nation for a design field that should have the safety of building and bridges as its highest priority?”.
Did we have contractors and builders with self-imposed quality control programs that were so much better than other states that code mandated quality control for the structure was not necessary? I found absolutely no evidence of that.
Did we have extremely low failures rates building structures and bridges in Wisconsin in comparison to all other states? I found no evidence of that either. In fact, Wisconsin ranks xxx out of the 50 states in terms of structural failure rates?
After 12 years, and several structural failures later, I find myself still wondering, “Why?”. Some speculation by other structural engineers seemed to suggest that designers in Wisconsin had a comfort level with contractors, quality control was “good enough”, and special inspection was just going to be an additional cost. Could it be that structural engineers were actually advising the state legislature that special inspection was an unnecessary cost?
In my time consulting to structural engineers, I am finding a strong distrust between structural engineers and builders/ contractors. Many, many times I heard the phrase, “I could have designed that structure more economically, but when in doubt make it stout and I [added extra thickness], [assumed a lower strength for the material than reality], or [bumped the member size up] just to be safe”. So, it seems those structural engineers that believed Special Inspection would just add cost to a project because engineers trust contractors who where overly optimistic, or simply wrong. Cost is being added unnecessarily at a much higher rate when you use “when in doubt make it stout”. In my estimation, the cost of “when in doubt make it stout” is two to three times more expensive than simple Special Inspection and quality control.
To me, what is even more troubling, is the fact that these “when in doubt make it stout” methods simply do not work. You cannot design for poor construction, as engineers we have to ensure our buildings are getting built as we designed them. I would like to think engineers are choosing a self-imposed special inspection program. Unfortunately, in the ‘low cost at all costs’ design world that we are currently in, that would almost guarantee you will not be selected for the next project.
So we left with over-designed buildings that are less safe. In my opinion, we all lose in this scenario – engineers are compromising their design values and adding additional cost, contractors are working without the proper quality control, and owners end up with a worse product at a higher cost.
As a design community, we must re-assess and demand our state laws be changed to include special inspections. We cannot afford the financial cost and the risk to human lives that we are enduring by not requiring Special Inspections for structural engineering here in the great state of Wisconsin.