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Tunnel support in South African mines
Published in Xia-Ting Feng, Rock Mechanics and Engineering, 2017
– Example 1: Straps and anchors – applied where tunnel deformation is likely, often installed over existing meshing and lacing. A regular pattern of 4.5 m or even 6.5 m long cable anchors are installed around the perimeter of the tunnel spaced approximately 1.5 m apart in a block pattern. The anchor cables are threaded through multi-strand narrow straps (Osro / Oslo straps) which are installed over the anchor pattern prior to the anchors being tensioned, thus locking the straps under the anchors’ load-spreading washers. The straps provide a load-spreading function between the different cable anchors.– Example 2: Steel arches or ring sets, combined with void filling – used in extreme cases, such as where the ground conditions do not allow reinforcement of the rockwalls using tendons or cable anchors, or where deformation of the tunnel cannot be contained by other methods. The arches or ring sets are passive support, so the void between the support and the adjacent rockwalls must be filled to provide some form of support and impact resistance. An example of steel arches being used to support the entrance of a chairlift excavation from surface is shown in Figures 12 and 13.
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Published in Les Goring, Residential Surveying Matters and Building Terminology, 2023
Floor-joist restraint straps: Figure 43: Modern construction methods, involving lighter-weight material in roofs and walls, have led to the need for anchoring straps, referred to in the Building Regulations’ Approved Document A, to restrict the possible movement of roofs and walls likely to be affected by wind pressure. Such straps are made from galvanized mild-steel strip, of 5mm thickness for horizontal restraint and 2.5mm thickness for vertical restraint. The straps are 30mm wide and up to 1.6m/5ft. 3in. long. Fixing holes are pre-punched along the length at 15mm/⅝ in. centres, to facilitate optional fixing points.
Tunnel support in South African mines
Published in Xia-Ting Feng, Rock Mechanics and Engineering, 2017
– Example 1: Straps and anchors – applied where tunnel deformation is likely, often installed over existing meshing and lacing. A regular pattern of 4.5 m or even 6.5 m long cable anchors are installed around the perimeter of the tunnel spaced approximately 1.5 m apart in a block pattern. The anchor cables are threaded through multi-strand narrow straps (Osro / Oslo straps) which are installed over the anchor pattern prior to the anchors being tensioned, thus locking the straps under the anchors’ load-spreading washers. The straps provide a load-spreading function between the different cable anchors.
Prefabrication of substructures for single-detached dwellings on reactive soils: a review of existing systems and design challenges
Published in Australian Journal of Civil Engineering, 2019
Bertrand Teodosio, Kasun Shanaka Kristombu Baduge, Priyan Mendis, David Jeremy Heath
Another novel substructure includes braced masonry piers or cast-in-place concrete pads with metal straps (Figure 5) that are utilised to resist vertical and lateral loads such as extreme wind conditions and earthquakes (Federal Emergency Management Agency 2009). The metal straps are integrated in the footing system redistributing the loads to adjacent portions of the footing system. Though if straps are loaded to their maximum capacity, redistribution of load may lead to progressive failure and collapse. To prevent progressive failure, redundant straps are necessary but may be inefficiently designed. These systems require typical ground improvement techniques such as ground compaction and application of gravel. The metal straps are installed and act as tie-downs to secure the house in place. The installation of these systems commonly takes approximately three to 7 days, depending on the configuration of a proposed substructure.
Effects of full body harness design on fall arrest performance
Published in International Journal of Occupational Safety and Ergonomics, 2021
In general, industrial full body harnesses conforming to Standard No. EN 361:2002 [8] are made of textile straps joined by seams and metal connectors in such a way as to securely hold the user and support his or her weight. Typically, the shoulder straps cross at shoulder-blade level. Depending on the harness design, they are in some way combined with the thigh straps forming loops around the user’s legs. In addition, the thigh straps may be transversely connected in the gluteal region by a so-called sit strap. The straps are usually made from polyamide or polyester fibers, or, for special purposes (e.g., heat exposure), from aramid or other advanced fibers. The minimum width of load-bearing straps is 40 mm, and that of accessory straps is 20 mm.
Personal protective equipments (PPEs) for COVID-19: a product lifecycle perspective
Published in International Journal of Production Research, 2022
Shubhendu Kumar Singh, Raj Pradip Khawale, Haiyong Chen, Haolong Zhang, Rahul Rai
In general, goggles comprise two primary parts-the lens and the frame. Usually, the goggles are manufactured by an injection molding process that involves injecting the polymer material into a metal mold to produce the frames and lenses' desired shape. Manufacturing processes may vary depending upon the particular type of goggle required as per the application domain. However, a generalised production process is as follows. First, a mold is created to render the desired shape to the goggles' lens and frame. The mold surface is highly polished to deliver a lens of high optical lucidity. Polycarbonate, a type of scratch-resistant and impact-sustaining plastics, is injection molded to form the goggle's lens portion. Polycarbonate pellets are heated inside an injection molding machine to a temperature higher than Celsius to convert it into fluid form. The fluid Polycarbonate is the infused into the shape under pressure for a time of 30–60 s. After injection, the material cools quickly and is then expelled from the mold. Contingent upon the mold design, various arrangements of goggles or glasses might be created with a single injection of materials. The most onerous task is to ensure that lens remains clean and clear for a long time of use, which is achieved by precisely controlling the pressure-temperature setting during the molding process. Third, the surface treatment process is where the injection molded goggles are dipped in a cleansing bath to remove any impurities present on the surface. After cleansing, the goggles are rinsed with clear water and are then placed in a chemical bath to apply a protective coating. Coatings such as anti-glare, anti-scratch, and anti-fog are used for the lenses, and these coatings protect the goggles against forging/misting and scratch. After coat, the goggles are heat cured at a temperature of , or more depending on the type of coating used. Following the heat treatment process, the final inspection is performed to check for distortions or imperfections. Straps are used to ensure that the goggles are secured around the head. Manufacturers use Neoprene and other elastic materials to make the strap.