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Questions tagged [structural-engineering]

Questions related to the integrity, design requirements, or analysis of structures.

Structures can be both large and small. Structures are not necessarily buildings or bridges.

Typical Structural Engineering concerns include, for a given loading on a structure or structural element, ensuring that:

  1. The stresses do not exceed a specified value
  2. The structure does not deflect beyond a specified value
  3. The structure does not buckle
  4. The natural frequencies of the structure are not excited

Sometimes, the given loading is unusual - such as wind or seismic loading. In these cases is it often appropriate to use additional tags to categorize the question.

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Why do wooden gate designs recommend a brace under compression instead of tension?

Looking at guides for building wooden frame gates I almost always find the following design recommendation: The idea is that the cross brace will distribute load from the top outside corner into the bottom of the hinge bracket. I understand this…
jesse_b
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What is the umbrella-like thing surrounding this new structure?

Recently this water tank was constructed (poured concrete). (I presume it is a water tank, as they laid blue plastic/PVC water pipe, perhaps 24 in. dia., in the vicinity at the same time.) After the outside was finished, they erected this dark…
user20010
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Fixing a Roof with Toe-bearing Rafters

I have acquired an old loading dock built in 1930 that has toe-bearing rafters in addition to undersized purlins. As you can imagine, many of the rafters have sagged. Also, because of the toe-bearing design of the rafter, the building has no…
alfreema
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What is the purpose of end plates when connecting beams together?

Quite often this kind of arrangement can be seen when beams are connected together. A rectangular plate is welded into a beam, and the plate is bolted to the other beam. I suppose one purpose would be simply that bolting is easier to do in some…
S. Rotos
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Where do the tributary angles/ratios for tributary areas come from?

When preparing load calculations for a slab, the quick method is to define the tributary areas of a slab for the beams/columns below. These are generally taken as lines at mid-span of the slab panels and, depending on the support conditions, at the…
SlydeRule
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Sign convention in Mohr's circle

I don't really understand the explanation in the circled part of the image below (from here). From the diagram, we can see that the shear stress that cause the element to turn clockwise is positive, but in the text there, the author stated that the…
kitzlong
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What is the difference between plastic and compact cross sections?

I'm studying beam cross section classifications here. It is explained that the difference between plastic and compact cross sections is that while both do develop their plastic moments, only plastic cross sections have sufficient rotation capacity…
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Wind load of panel

I am planning a prop for a marching band show and I want to determine how to best address the challenge of the wind blowing it over. This is definitely not my area of study and I am hoping for some guidance here. The panel is 10' high and 4' wide. …
itsmatt
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Safety of suspended (drop) clay ceiling tiles

Drop (suspended) ceiling tiles are of course quite common, but I am in the process of trying to evaluate the long term safety of a specific kind of suspended tile made of fired clay. When installed it looks like this The tile measures about 12…
Ram
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What is the unbraced length of the compression portion of an X brace?

In the diagram below, the compression member is $AC$. What is its unbraced length for determining buckling capacity? This also matters because certain codes put limits on the maximum value of $\frac{KL}{r}$ for bracing members. I know that the…
hazzey
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Standard specification for direction of lateral load for beams

I have always thought that lateral load is horizontal and not vertical in direction. For example, from this MIT notes and many others: The lateral load resisting systems for earthquake loads are similar to those for wind loads. Both are designed…
Robert H
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How do you account for buckling in a brick and mortar structure?

I was thinking about this question from quite a while back about height limits of a brick and mortar tower. One answer pointed out that, due to the high compressive strength of brick, one could build a tower 7.4 km high without taper before…
mart
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Angle Iron Cleat at Slab-Slab connection

We regularly bolt an angle iron against an existing building element (flange down), and use the flange as support for a new concrete slab. Is there any design approach to assist with the sizing / spacing of the chemical anchors as well as confirming…
SlydeRule
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Probability of structural failure

In structural engineering we have to accept the fact that you can never be exactly sure how much load a structural member can resist, that the load carrying capability of an element is not one exact value but distributed with some probability…
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Why do cold formed sections buckle differently from hot finished?

Above is a chart from a Eurocode handbook. It gives a correct buckling curve depending on cross section and its dimensions. I noticed that for hollow sections, the choice depends on whether the section is hot finished or cold formed. Why does it…
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