A Paradigm Shift
Change is hard. People resist it. It’s easy just to keep going down the known path.
I ask that you humor me by reading this article with an open mind.
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How it may affect the Profession. Part 1
It is almost impossible to open a magazine, pick up a newspaper or listen to the news without seeing a reference to climate change and its effects. Unfortunately, the issue has become very politicized, in part because of the tremendous amounts of money at stake.
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It can be cost-effective to design wood structures for resilience and safety during fire events.
With growing public interest in sustainable building and with the addition of “mass timber” Construction Types IV-A, IV-B, and IV-C to the 2021 International Building Code (IBC), design professionals are increasingly required to design mass timber building elements to fire-resistance ratings prescribed by the IBC. While many members of the public, and even building design professionals at times, associate wood construction with inherent fire risks, it is feasible and can even be cost-effective to design wood structures for resilience and safety during fire events.
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As I embark on my year as NCSEA President, I have a renewed sense of awareness and appreciation of all of the great work that CASE, NCSEA, and SEI are doing to advance the Structural Engineering profession. I am also inspired by the engagement of so many individuals within various levels of our organizations, working together with a common purpose. Those who have engaged already recognize the value of participation and the benefits of both investing in their career and doing their part to help advance our profession. If you missed it, I encourage you to read the editorial by Jeannette Torrents from the February issue on “The Value of Participation.”
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Unintended Consequences
Many brick-clad buildings constructed from the 1950s through the 1970s employ an early version of cavity wall construction that looks like contemporary veneer wall construction from the outside but has different structural behavior. Repairs and modifications to such cavity walls that are seemingly cosmetic or undertaken to improve envelope performance can change the wall’s load path and impact its ability to resist lateral loads. Owners, contractors, and design professionals should be able to recognize cavity wall construction, understand when potential repairs or modifications warrant structural evaluation, and design and implement structural strengthening when required.
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Updates to the Building Code Requirements for Masonry Structures.
The 2022 TMS 402 Building Code Requirements for Masonry Structures added Appendix D for glass fiber reinforced polymer (GFRP) reinforced masonry. GFRP reinforcement is non-corrosive, non-conductive, and not thermally conductive, so there is no thermal bridging. Due to these properties, GFRP reinforcement is advantageous in the masonry near electromagnetic equipment, such as MRI rooms in hospitals and masonry walls near high-voltage cables and transformers in substations. Other applications include walls exposed to severe environments, such as in coastal construction, seawalls, and chemical plants. The lightweight nature of the GFRP bar, being one-fourth the steel weight, allows for production efficiencies for the contractor and health and safety benefits to workers.
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The key is not too much of a good thing.
Designing structures that resist failure due to seismic activity safeguards occupants from injury and reduces the need to rebuild after an earthquake, which can decrease the total embodied carbon a site represents. As such, seismically resilient structures contribute to sustainable construction practices by reducing the environmental strain caused by material production, transportation, and construction.
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What Structural Engineers Should Know About GFRP Reinforcement
In steel-reinforced concrete (steel-RC) structures, reinforcing steels corrosion reduces the structure’s lifespan and requires expensive repairs. When steel-RC structures are exposed to moisture coupled with chlorides and CO2, concrete deterioration is caused, leading to significant repairs typically after 25 years of service. As the structure ages, major repairs can be expected every ten years until it needs to be replaced, typically after 50 to 75 years of continuous service. Researchers and engineers have been studying corrosion in concrete structures and exploring ways to prevent it. The use of Fiber Reinforced Polymer (FRP) reinforcing bars was considered in the early 1960s as one potential solution for preventing corrosion in reinforced con-crete. There was a significant development in FRP research, field demonstrations, and commercialization starting in the 1980s and continuing since then.
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19th Century Mississippi River Bridges Series
The Chicago, Burlington & Quincy Railroad started very small in 1849 with lines around Chicago and points to the southwest. By 1864, it had extended its lines southwesterly to the east bank of the Mississippi River, opposite Burlington, Iowa. A car ferry carried the train across the river where it connected with the Burlington and Missouri Railroad that had been incorporated in 1852 and expanded westerly, reaching the Missouri River by January 1, 1870.
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Flexural analysis and design of beam sections are fundamental topics in reinforced concrete structures. However, many engineers and students have difficulty generalizing the basic analysis and design principles into more general and complex cross-sectional shapes other than simple rectangular cross-sections. This article presents the flexural analysis and design of general beam sections in a rigorously derived framework and builds a foundation for their design. Part 1: Section Analysis focuses on the flexural strength calculation (analysis) of any given beam section. Part 2: Section Design focusing on the flexural design aspects of beam sections will run in a future article.
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