![]() It is one of five poteaux-en-terre buildings that survive in the US. Note how the rafter poles for the gallerie tie-in. A double roof (using a Norman truss), common rafters supported by principal rafters ( top chords in this case) and an unusual extra layer of common rafters on the lower half to form a gallerie. Under the midsections of the rafters are purlins which support the common rafters and are supported by principal rafters. There is not always a ridge board or beam where the rafter tops meet. Common rafters without collar beams form most of this roof. For other uses, see Rafter (disambiguation). The use of cast-in-place concrete floors and roofs, because of the time needed for forming, pouring, finishing, and curing, requires a building plan which is large enough to permit the masonry work to progress in one part of the structure while the floor in another area is completed.This article is about the structural beam. Once cured, the precast slabs are lifted to their final location. Where sufficient space is available at the job site, precast slabs can be formed in stacks on-site, starting with the roof slab and using the top surface of the lower slab as the form for the next slab. For example, hollow core prestressed slabs can be erected quickly, without the need for formwork or shoring. Depending upon the size and number of stories associated with a given project, one concrete framing system may have unique benefits over another. Concrete SystemsĬoncrete slabs can take many forms, including prestressed, precast, and cast-in-place construction. Proprietary systems that use concrete masonry units as a filler between the steel joists are also available. Steel bar joists typically use pocketed or ledger connections to concrete masonry walls. Steel-framed roofs using steel bar joints are very common in commercial structures because they are capable of spanning long distances. To prevent the resulting unwanted decay, the lumber used should be pressure-treated, naturally decay resistant, or have a moisture barrier placed between the wood and the concrete masonry. Wood in contact with masonry materials may absorb moisture present in the concrete masonry causing the wood to rot. It is imperative when constructing a wood-framed system that it not be in direct contact with the concrete masonry. ![]() Wood framed floors and roofs are common in residential and low-rise construction. Wood, concrete, and steel are among the most frequently used framing materials in these applications. Several materials are common to roof and floor construction. Normally flashing is not provided in interior walls. Note: Most of the connections herein depict flashing for water penetration resistance which should be used in all exterior walls. A ledger connection reduces the necessary pre-planning and does not unduly impact the mason’s work as opposed to a pocket connection thereby reducing the number of field modifications. Ledger Connection – As with hangers, ledger connections minimize the impact on the continuity of a masonry wall.However, hangers approved for direct attachment to the surface of a masonry wall are also available. Hangers are generally anchored to a wall through a joint and into a bond beam. Hanger Connection – When it is desired to maintain the continuity of the wall for structural, aesthetic, or construction reasons, a wall hanger can be used to suspend the roof or floor system.Care must be taken to insure that the use of a pocket does not interfere with the continuity of the vertical reinforcement in the wall. This detail is used when masonry continues above (either as part of the wall or as a parapet) the connection location and eccentricity is to be minimized. Pocket Connection – A pocket connection consists of framing the floor or roof system into a void in the masonry wall.This connection is used at the top of concrete masonry walls or when a change in wall thickness provides a ledge with sufficient bearing area as shown in Figure 1. Direct Bearing Connection – The direct bearing connection is often the simplest type of connection.The four primary types of connections, each having specific advantages, include: Additional requirements may be necessary in some locals, particularly where earthquake and high wind forces are to be resisted. The connections detailed herein address minimal requirements. Connections critical to the integrity of a structure. ![]() The transfer of loads between diaphragms and walls requires the proper design and detailing of the connection linking these elements.
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