Review Category : Building Blocks

Achieving AESS and AESSS Goals

When properly executed, the decision to expose structural steel offers a powerful opportunity to express a project’s tectonics and aesthetic goals. The 2016 American Institute of Steel Construction (AISC) Code of Standard Practice for Steel Bridges and Buildings (ANSI/AISC 303) introduced the architecturally exposed structural steel (AESS) category system, a systematic method of communicating craftsmanship quality to support goals for the final appearance of the finished structure. Prior to 2016, the lack of a categorized approach uniformly accepted by the Architecture-Engineering-Construction industry posed challenges in communication between the design and construction team, as well as with Owners. Today, when properly understood and leveraged, the Category system can support project outcomes that meet designers’ intent, are properly budgeted during the bid process, and achieve ultimate aesthetic goals for which fabrication quality is a foundation.

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Myth Versus Reality

Lightweight concrete has been a staple of the built environment for centuries, predating the Roman Empire. While some early lightweight concrete structures still stand, their materials bear little resemblance to today’s offerings. Industry professionals now recognize structural lightweight concrete as a strong, low-density mixture of Portland cement, water, and various combinations of normal weight aggregates and lightweight aggregates. In such concrete, lightweight aggregate produced from shale, clay, or slate is heated to approximately 2000 degrees F in a rotary kiln process. During this process, it softens and bubbles form that remain as unconnected pores when it cools.

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The Untold Life Cycle of a Steel Joist

The attributes of open web steel joists are well known to the structural engineering and construction community. Their efficiency, high strength-to-weight ratio, versatility, ease of erection, high durability, and cost-effectiveness make steel joists and joist girders a common consideration for today’s roofing and flooring systems. However, the manufacturing of open web steel joists and joist girders is often left out of the discussion, leaving engineers and decision-makers wondering what kind of processes occur behind the curtains of the manufacturing plant. This article aims to shed light on the typical life-cycle stages of steel joists, from steel production to building decommissioning, leading the readers into the realm of open web steel joist and joist girder manufacturing and sustainability.

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Design and construction professionals face significant challenges driven by increasing customer demands, rapidly changing material costs, strained supply chains, and the loss of workers going into trades. However, a more urgent issue is that climate change is a real and growing concern. Given that concrete is the most widely used manufactured material in the world, the Portland Cement Association (PCA) has challenged the design and construction industries to address the issue by developing a roadmap to carbon neutrality by 2050. Optimization, avoiding overdesign, designing for performance, and leveraging technology are critical parts of the path (Figure 1).

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Part 2

This is Part 2 of a two-part series. Part 1 (STRUCTURE, September 2021) summarized two methods, including equations for finding available strengths for aluminum based on tests. It also includes plots of calculated safety factors for various conditions. Part 2 compares results from these methods. Please note that Figure numbering continues from Part 1.

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The Fast and the Slow

The crack patterns in broken glass and their fracture surface details describe the origination and energy intensity that caused breakage. This article discusses basic fracture technology of flat glass in architectural and structural glass assemblies, illustrating characteristic fracture surfaces and crack patterns. The objective is to provide information to engineers investigating glass breakage and tips for specifiers to avoid glass breakage problems.

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Reliable connections in structural steel assemblies must accompany superior corrosion protection. Hot-dip galvanized (HDG) coatings produce maintenance-free corrosion protection for many years. The structural connections must provide equivalent corrosion protection as well as structural integrity to ensure maintenance-free performance. A solid structural connection is ensured by providing corrosion protection for the bolt and nut connection and providing clearance for the HDG coating special treatment of the nut. A critical factor in structural connections is the slip factor for the faying surfaces. This article discusses recent changes made by AASHTO to the design parameters for HDG faying surfaces and the increased clearance holes for connections using bolts with a diameter above 1 inch.
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