How structure engineer use gravity and lateral loads to design building structure?

Hi all,

I have a question regarding the general structure design. In real practice, does the engineer need to use both gravity and lateral loads for a building structure design? By going through Ballast and Brighwood’s study material, I feel the lateral loads control everything, like structure element size, connection details. however, there is no clear description for this.

Or I guess there is another way to do it. The structure engineer would use gravity load to calculate the structure elements’ sizes first, then use lateral loads to double check them. Then decide which loads take the control.

What do yous think? any help or reading material suggestion is highly appreciated, Thanks. I am also interested in joinning BS monthly plan, will BS material cover such topics?
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Hi @jameslixing ,

Structural design definitely has to account for lateral loads and ‘gravity loads’.

Let’s review what loads effect buildings:

As far as vertical forces on structure, you’ll mainly hear them referred to as “dead loads” and “Live Loads”. Dead loads are the loads that are permanent, those that comprise of the building itself including structure and façade. Live loads are those that may change over time including occupants, furniture, snow, etc.

Lateral loads are those that are affecting the side of the building. For example, wind or earthquakes. Imagine two columns with a beam on top. This might adequately hold a certain amount of weight. But, without lateral reinforcement, that structure will topple easily if force is applied to it’s side. Lateral forces are dealt with through such elements as shear walls, cross bracing, or moment connections.

If you’re interested in learning more, I’d definitely check out Black Spectacle’s lectures. The lectures are organized by the objectives listed in the ARE 5.0 Handbook.
So, I would start with lectures for PPD Objective 1.3:

Of course, I always recommend Ching’s “Building Construction Illustrated”. There’s a few other books on the ARE 5.0 references defined by NCARB which you might find helpful:

Hope this helps!

Hi, Darion:

Thanks for your response. I believe I made some progress. My question was asking how and where the engineers would use gravity load for the calculation.

by going through the structure lectures you mentioned and some calculations, I found out the calculation involving with gravity loads on many ways, explicitly on some areas, like beam and overturning related calculations.

Thanks again for your help.

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