T-sections are load-bearing structures made of reinforced concrete, wood, or metal that are used in construction. T-sections are sometimes known as T-beams or T-bars, depending on how they are defined. They are cross-sectional structural beams having a "T" form. The word "T" is used because there are two parallel faces, one on each side of the center line.
T-sections can be used instead of I-beams for longer spans. They require less material than an I-beam of the same weight, and so are cheaper. T-sections also allow for more design flexibility since they do not have to be perpendicular to the axis of the foundation. This is not possible with I-beams because they must be mounted at right angles to the foundation wall.
The three main types of T-sections are:
1 Reinforced Concrete T-sections - These consist of a top plate, bottom plate, and two upright web walls connecting them. The top and bottom plates are flat, but the webs may be profiled to increase stiffness or reduce weight. The reinforcing usually takes the form of wire cages embedded in the concrete.
2 Timber T-sections - These are built from timber members joined together at right angles with adhesive, fasteners, or steel ties. The main types of timber used are pine, oak, and maple.
As tension members in bridge girders, angle sections joined by plates, as indicated in figure (d), are employed. A built-up section is composed of two channels arranged back to back with a gusset in between. In a single plane truss, such sections are utilized for medium loads. They require more material than flat plate and open web bridges.
In closed web bridges, the angle sections are usually hollow to reduce weight and increase strength. The hollow sections may have solid walls or be completely open. These types of sections are used for light loading on large spans.
In flat plate bridges, the angle sections are also hollow to reduce weight and increase strength. However, instead of using gussets, flanges are used at the ends of the plate. These types of sections are used for heavy loading over small distances. They require more material than double-webbed bridges.
Double-webbed bridges consist of two sets of parallel webs connected by cross-members. Each set of webs is attached to one side of the girder, while the cross-members connect the two sets together. This type of section is used when the load needs to be distributed evenly across a large surface area. It requires the most amount of material of all three types of sections.
Tension members should not be confused with tie rods, which are devices used to join adjacent segments of a suspension system.
WT sections are widely utilized as chord members in roof and floor trusses that are weakly to moderately loaded. These elements are exposed to combined axial and flexural loads in this application. The ASD Specification does not address the design of these parts for flexural loads. However, many truss manufacturers produce charts showing allowable deflections for various sizes of WT sections when subjected only to axial load.
When used as floor joists, WT sections must be long enough to support the anticipated live load. Charts are available from several sources that show the relationship between the depth of a floor joist and its width. For example, the American National Standards Institute (ANSI) provides guidelines for determining floor joist sizes that will support specified maximum loads. The ANSI standards are listed in the NAS document above. Also see BOC documents below for further information on WT sizes.
Roof truss designers often use a single large piece of wood as the WT because it is less likely to twist under load than multiple small pieces of wood. The size of the WT affects the cost and availability of suitable material. Larger WTs require more-dense species of wood than do smaller ones. Also, larger trees are usually needed to obtain sufficient wood length for large trusses.
Floor truss designers often use multiple narrow strips of wood as the WT because it is easier to fabricate into a required shape.
Sections serve the same goal as any other view of the model: to transmit information to the builder that is required for building. Sections are often helpful for displaying vertical relationships that are not obvious in elevations, such as how floors meet walls, floor-to-floor measurements, and so on. They can also be used for showing horizontal relationships, such as wall studs and joists.
The most common use for sections is to show floor plans on an electronic drawing board. The floor plan can then be modified easily by simply changing the corresponding elevation.
Other examples include showing rooms when listing properties for sale, highlighting construction issues when inspecting buildings for repairs, and so on.
Sections can also be used in more creative ways if you want to display information that cannot be represented in an elevation. For example, you could create a section showing the average temperature in various parts of the country over time by using data markers to mark specific locations on the elevation and then calculating the average temperature for each marker group.
Sections are particularly useful when dealing with large or complex models because they can help reduce the amount of detail that needs to be displayed at one time.
For example, if you were to draw every single stud and joist in a building structure diagramed on a map, this would take up a lot of space and be very confusing.