Loads are a basic component of Building design. Without load calculations, there is no way of knowing how well your building will perform when it is subject to forces such as wind, earthquakes or even the activities that go on in the building. Without these calculations the building may even collapse under its own weight. If you purchase house plans and proceed to make modifications to the design without consulting the building designer or a structural engineer, you are, so to speak, throwing caution to the wind.
To start, there are dead loads. These are come from the building itself. They are the weights of the structural elements such as roof, floor and wall framing, cladding and finishing, any mechanical elements such as plumbing and electricity, as well as the building’s other permanent components, including HVAC and specialized equipment that are there to fulfill the intended uses of the building. These weights are not expected to move. The actual weights of all these elements must be determined in order for the structure to safely accommodate the loads in a way that transfers them downwards through the structure and safely to the foundations and into the ground itself.
Then there are live loads, also known as temporary loads. This includes the weight of the occupants of the building, its furniture and anything that might foreseeably be moved into the building over the course of its lifetime. Again, the intended use of the building comes into play here as there will be different expected loads for different uses: an office area will have different load requirements than say a cafeteria, which can be considered an assembly area, and have many more people present per square meter at a given time.
Next there are special loads. They are much like dead loads except that they must be accommodated for in their specific area of the building. If you have large mechanical equipment or a large fixture in a specific area, then the floor structure beneath it might require additional reinforcement such as additional support or blocking.
Wind can create lateral loads, but also upward loads on roof structures and even separate a building from its foundations. Earthquakes also create lateral forces. These must be dealt with as per regulations enforced in the area. This entails creating a lateral force resisting system out of the structural elements that make up the building that can successfully transfer the load into the ground. It means adding what is called a sheer wall. A sheer wall has more reinforcement than a standard wall and it is anchored to the ground in a way that can convert lateral forces vertically and into the ground.
Snow load requirements are enforced in many areas too. Snow loads can last several weeks and fall into the Special load category.
Make sure your loads are calculated
As always, make sure the plans you are working from are compliant with local codes. But just as importantly, make sure all load calculations are accounted for.
If you’re using TRIFORCE® open joist in one of your projects and aren’t sure about your load calculations, please don’t hesitate to contact us.