Lateral Bracing & Stability

Some people believe that building design is simple. They may believe that anyone can build a house or a deck, and that no engineering expertise or understanding is required. Placing a beam here is a good idea. There's a post there. Here's some concrete. There are a few nails there. But what if the big evil wolf appeared, huffed and puffed, and attempted to topple that structure?

There are two basic forms of lateral loads that can be applied to a structure, as I explained in our essay on loads: wind loads and seismic loads. Many people are aware of which structural elements can withstand vertical loads. Beams and columns are what they're called. But what if the structure gets hit by a strong gust of wind, or Godzilla comes rampaging through your neighbourhood, causing the ground to shake/vibrate? What parts are required to withstand those lateral loads and prevent the structure from collapsing?

In the event of lateral loads, a structure requires a lateral force resisting system (LFRS) to guarantee lateral stability. These lateral loads are based on worst-case loading scenarios, such as a wind gust that occurs once per 50 years. If we're lucky, the building will never have to deal with these loads, but it's important to plan for them in case they do. Whatever material the building is made of, there is almost certainly a technique to stabilise it to withstand lateral loads.

If you were standing on one foot and were given a strong push in any direction, you would most likely fall over. If you were standing on two feet shoulder width apart and someone gave you a strong push, depending on which direction the push came from, you might find yourself standing tall or flat on your stomach. If you're being pushed from behind or in front, your two legs won't provide much support unless your shoes are securely fastened to the floor. Your legs, along with your upper body, operate as a braced frame that provides lateral stability if you are pushed from the side.