Understanding Large Moving Doors… Hydraulic Or Bifold Doors
Quote… A farmer asked…
When the door is hanging straight out there, you better have something strong holding those cylinders. Doesn’t the door put a lot of stress on the building?
That goes for both style of doors.
Quote… A engineer once said…
The doors WILL find the weak points in our building design. Many wood building engineers have a tendency to get lax with the design of the door supports and framing surrounding your doors and forget that we not only have to support the weight and wind on the door, we also have to support its operation.
NOTE:“It’s better to overbuild than make costly repairs later”
- Building does not have to be made stronger.
- Building does not have to be modified to hold a hydraulic / bifold door.
- Building does not have to be engineered with extra reinforcing to accept a Hydraulic/Bifold Door.
- Door does not hang on your building . . . What does the door and frame attach to?
- The door is self-supporting and does not add any load to your building.
Is the door like a billboard? Could the door be erected in your parking lot ? The door could not possibly be erected independent of your building. The only way that the door would not add load to your building is if they were selling you a billboard that would lift itself without falling over. Otherwise, all of the forces and loads from the door opening and from windloads gets transferred through the door subframing to your building.
- When anyone tells you that the door does not put load your building, that should be a red flag to tell you that they don’t understand large moving doors.
- Door can be left open in windy conditions, BUT can the buildings withstand the forces…
USE COMMON SENSE when designing your building to accept a Hydraulic or Bifold Door
And refer to the SCHWEISS DOOR SPECIFICATION SHEETS and Reactions sheet to help understand the forces.
Schweiss Specs are supplied with each door.
HORIZONTAL DOOR COLUMN BRACING…. INCREASE THE TORSIONAL STIFFNESS OF THE DOOR COLUMN
- Hydraulic doors come with two powerful cylinders that are pre-mounted to a vertical subframe, one cylinder on each side of the door opening.
- The subframe that the hydraulic cylinders attach to must be fastened to the buildings door side columns.
- The hydraulic cylinders exert strong rotating forces to the buildings door side columns as the door is being operated.
- It is important to limit the rotation of the door side columns as the door is opening and closing, also when in the open position.
- To aid in limiting this rotation, horizontal braces are strongly recommended at the point on the door column where the cylinder attaches.
- Horizontal bracing is used to stop the doors vertical subframe, cylinder bracket and buildings door side column from twisting.
- The door cylinders and cylinder plate attach to vertical subframe members which are all connected to the buildings door side column on each side of the door opening.
- To help resist the torsional forces in the door side column, use horizontal bracing to the next adjacent building column in the plane of the door.
- These horizontal braces help resist the torsional load in the door side column.
THINGS TO CONSIDER WHEN PREPARING YOUR BUILDING FOR A HYDRAULIC/BIFOLD DOOR
#1. . . . . Is bracing necessary and what should the bracing look like.
#2. . . . . Poorly designed buildings and buildings that are designed properly.
#3. . . . . Old and new buildings.
The strength of columns and beams is a function of the material (steel or wood) and its size (2×6 is stronger than 2×4 because it has more material) and how it is braced (stability). Even very large (seemingly strong) columns do not have much capacity if they are not braced.
The larger the column size, the less bracing it usually needs. It is possible to design columns as (unbraced) but the size of the column tends to become very large and would likely be aesthetically unacceptable.
If we are going to brace columns, what does the brace need to look like? Braces on columns need to brace each axis of the column. You typically need less bracing on one axis of the column than the other. You also need to make sure that the bracing is effective. Effective bracing keeps the column from buckling (like when you put a straw between your fingers to see it bend), it also has to keep it from rotating. Rotation can be caused by axial load, when the entire column is loaded, if the outside face of the column is braced, but the inside face or flange is not. For columns that have an unbraced inside face or flange, additional bracing is usually required. Metal building people typically use flange braces, but the bracing may be horizontal to a second column that is near the column you want to brace (lean-on bracing).
This leads to the second topic of building design.
The building could be considered to be “acceptably designed” if the designer is told the correct loads that are going to be put on the building (dead load, torsion, eccentric loading, etc.) and they have designed the building to resist all of those loads. A “better design” would consider the desires of the customer. For example, if the customer were going to have an interior finish, you want the braces designed so that they did not extend beyond the inside face of the column.
The question of existing buildings:
Existing buildings can be a bigger problem. They were probably not designed for whatever you want to do or add to your building. The original designer or building company may not be willing to help. It is important to either have a qualified engineer or the original designer or building company design the modification using the correct loads and eccentricity information. All of the “recommendations” that Schweiss has on their spec sheets are good basic common sense recommendations that go a long way toward making the building right. The final responsibility lies with the building owner of an existing building. If they get a qualified engineer or the original engineer or building company to help them, then they can take that responsibility. The qualified engineer or original engineer or building company can look at Schweiss’ recommendations and decide what is really required.
The hydraulic cylinders exert rotating force to the building door side columns as the door is being operated… See Below
Horizontal Bracing…increase the torsional stiffness of the door columns
The subframe that the hydraulic cylinders attach to mount to the building door side columns. The hydraulic cylinders exert strong rotating forces to the building door side columns as the door is being operated. It is important to limit the rotation of the door side columns. To aid in limiting this rotation, horizontal braces are strongly recommended at the point on the door column where the cylinder attaches.
Horizontal bracing is used to stop the doors vertical subframe and cylinder bracket and buildings door side column from twisting. To help resist the torsional forces in the door side columns, use horizontal bracing to the next adjacent building column in the plane of the door. These horizontal braces help resist the torsional load in the door side columns.
Shows where a header is installed in an endwall of a building. The header is positioned up above the bottom of the rafter so you won’t lose any headroom!
Open Endwall Rafters – Header Placements
We work with old or new buildings to make your bifold door work.
Shows where a header is, using the bottom chord in an endwall of a building.
The engineered rafters can be doubled up to sufficient support.
On double endwall trusses where the outside ply is a “Gable Type” truss and the inside is an “Intermediate Truss”, there will be locations where there is a 1:50″ space between the vertical stiffener and the horizontal members of the gable truss.
The Customer is Responsible for the Building Structure & Bifold Door Header.
Schweiss Bifold Doors can fit any steel buildings, old or new providing a commercial door that suits your needs.