Review Category : Construction Issues

Tendon Repairs and Modifications

Post-tensioning is the most significant development in the concrete construction industry since steel reinforcement was first employed in the mid-1800s. Post-tensioning (PT) delivers roughly four times the tensile strength compared to conventional reinforcement and significantly reduces (or eliminates) concrete cracking, thus enabling thinner slab construction – reducing the environmental impacts, saving material and labor costs, and shortening construction schedules. Post-tensioning also brings a host of seismic advantages to a structure and enables architects to employ concrete in artful shapes and sizes once thought impossible.

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Helical piles are subject to special inspections, similar to deep foundations, but engineers have several choices when looking for the best way to install them. Currently, there are no standards for the installation of helical piles. However, helical piles should be installed and inspected in accordance with all relevant requirements listed in the governing building code.

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Post-installed expansion anchors are used to attach fixtures to concrete and masonry. Expansion anchor types include torque-controlled anchors, which must be torqued to expand wedges, and displacement-controlled anchors, which require impact forces on a sleeve or plug to expand wedges. Expansion anchors that rely on torque to expand wedges are referred to as torque-controlled expansion anchors. This article discusses the importance of torque on the installation and performance of torque-controlled expansion anchors installed into concrete.

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Membrane roof systems installed on steel roof decks traditionally result in a uniform transfer of wind (uplift) loads from the roof membrane to the steel roof deck and underlying supporting structure (e.g., steel joists). For example, in a built-up membrane roof system – which has been used commonly in the U.S. roofing industry for more than 125 years – the built-up membrane is continuously adhered to rigid board insulation.

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Have you ever been in a discussion, adversarial or entertaining, with a non-engineer or even an engineer, about what code requirements exist for construction activities? For example, a discussion about the generation of structural calculations for an existing building where the construction does not comply with the permitted construction drawings and, in some cases, with specific code requirements.

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After you finish the engineering on a project and it goes out the door, what happens to it? Who is responsible? How will it perform versus the engineering assumptions?

Over the years, the reality of what gets engineered versus what gets constructed has become more concerning. Performing site visits to observe construction configuration and specifics of the contractor’s interpretations of the permitted drawings has been, to say the least, enlightening.

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From Mix to Plant to Placement

Over the past decade, the use of high-strength concrete has gone from the exception to the norm. Uses of concrete strengths exceeding 10,000 psi are easily achievable on any building. The use of cold or hot weather concrete, high-performance concrete, self-consolidating concrete, architectural concrete, etc. is increasingly common, even for small projects.

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Replacing Riding Surface to Maintain Structural Integrity and Durability of an Orthotropic Deck

In 1967, the San Mateo/Hayward Bridge incorporated the United States’ first orthotropic steel bridge deck on a major bridge, winning the American Society of Civil Engineers’ (ASCE) Outstanding Civil Engineering Achievement Award (OCEA). The mile long orthotropic steel deck is included within the six lane wide, two mile long steel high-rise portion of the seven mile long bridge.

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