Hold down (structural engineering)

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A hold down resisting uplift from a timber shear wall HoldDown.JPG
A hold down resisting uplift from a timber shear wall

Holdown (holdown, hold-down, or hold down) or tie-down in structural engineering refers to the steel device or hardware that is installed at the end of a plywood shear wall. The hold downs provide uplift resistance against the overturning moment imposed on the wall due to "in-plane" lateral load applied at the top of the wall. A hold-down may also refer to clamping device used to anchor a pipe to a structural steel element or concrete floor or allow movement of the pipe in an axial direction. [1]

At the bottom, the hold down is connected to the concrete foundation or structural slab by an embedded or epoxied anchor bolt. At the top, the hold down is connected to a wood post with screws, nails or bolts.

Hold-down clamp for anchoring pipes Hold Down Clamp.jpg
Hold-down clamp for anchoring pipes

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Wall plate

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Stone veneer

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Anchor bolt Connection elements that transfer loads and shear forces to concrete.

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Anchor plate Large plate or washer connected to a tie rod or bolt

An anchor plate, floor plate or wall washer is a large plate or washer connected to a tie rod or bolt. Anchor plates are used on exterior walls of masonry buildings, for structural reinforcement. Being visible, many anchor plates are made in a decorative style.

A pipe support or pipe hanger is a designed element that transfer the load from a pipe to the supporting structures. The load includes the weight of the pipe proper, the content that the pipe carries, all the pipe fittings attached to pipe, and the pipe covering such as insulation. The four main functions of a pipe support are to anchor, guide, absorb shock, and support a specified load. Pipe supports used in high or low temperature applications may contain insulation materials. The overall design configuration of a pipe support assembly is dependent on the loading and operating conditions.

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Hybrid masonry

Hybrid masonry is a new type of building system that uses engineered, reinforced masonry to brace frame structures. Typically, hybrid masonry is implemented with concrete masonry panels used to brace steel frame structures. The basic concept is to attach a reinforced concrete masonry panel to a structural steel frame such that some combination of gravity forces, story shears and overturning moments can be transferred to the masonry. The structural engineer can choose from three different types of hybrid masonry and two different reinforcement anchorage types. In conventional steel frame building systems, the vertical force resisting steel frame system is supported in the lateral direction by steel bracing or an equivalent system. When the architectural plans call for concrete masonry walls to be placed within the frame, extra labor is required to ensure the masonry fits around the steel frame. Usually, this placement does not take advantage of the structural properties of the masonry panels. In hybrid masonry, the masonry panels take the place of conventional steel bracing, utilizing the structural properties of reinforced concrete masonry walls.

Mechanical Plastics Corp. is a company based in Norwalk, Connecticut that "produces screw anchors and toggle bolts used in the construction industry." These anchors, which range from light-duty to heavy-duty, are "used to fasten objects to walls, ceilings, and floors made of concrete, brick, cement block, drywall, and fiberglass". Mechanical Plastics Corp. currently contains two main divisions, TOGGLER and Wej-It. According to The New York Times, Mechanical Plastics currently distributes its products to twenty-four countries internationally, and these products are then sold at retail stores such as Lowe's. TOGGLER anchor system, whose patents are owned by Mechanical Plastics Corp., is used in the area of home improvement, when driving "a screw or nail directly into a framing member behind the wall surface" is not possible and it is necessary to choose a fastener that is "specifically designed for gripping in the hollow spaces between the studs and joists." Mechanical Plastics Corp. also manufactures the Wej-It expansion bolt, which "is a one-piece all-steel anchor for attaching anything to concrete, brick, or stone."

References

  1. Hold-Down Pipe Clamps. Piping Technology and Products, (retrieved May 2012).