Review Category : Structural Practices

A metallized coating (a metallic alloy applied to a base metal or concrete) is intended, in most applications, to be a form of protection to an underlying metal substrate. The act of applying the coating is referred to as metallizing. Metallizing can be achieved in several ways such as hot-dipped galvanizing or thermal arc spraying, applied in situ or in a shop. Zinc, which was first used in construction in 79 AD, is the most used metal for this process. Half of the zinc produced today is used for corrosion protection of steel.

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In Ground Improvement for Building Support by Damian R. Siebert, P.E. and Steven R. Kraemer, P.E. (STRUCTURE, July 2015), we learn more about issues surrounding the ground improvement (GI) for a building support system (stone columns, aggregate piers placed under reinforced concrete footing). It is an intermediate foundation system, i.e. the system between shallow spread footings and deep pile foundation systems. Although the system has been around in Europe since the 1930s and in the U.S. about a decade later, it remains mostly in the hands of the specialty contractor’s foundation engineers.

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In the engineering and construction industry, any truss spanning more than 60 feet is considered to be “long span”, thus requiring engineering consideration (per International Building Code (IBC) 2015 Section 2303.4, “Trusses” [for design of]). The purpose of this article is first to explore and explain various aspects of building with long-span, open-web trusses, including manufacturing, architectural design options, engineering considerations, and installation practices and, second to provide examples of structures where long-span, open-web trusses are featured (Figure 1).

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The authors recently conducted a study into the elastic behaviour of thin (Kirchhoff) plates using commercial finite element (FE) software. In attempting to verify the FE solution, it was compared to results presented in Timoshenko’s text and a significant difference was observed. This article presents the work conducted to uncover the reason for this difference and reveals an error (probably typographical) in the text. The source of the error is identified and it is demonstrated how such errors might propagate into other texts on the subject of plates. The significance of the error to the practising engineer is also discussed.

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Structural engineers know the mechanics of the seismic provisions of the International Building Code (IBC) and ASCE 7-10. They know how to get Ss and S1 for a site and apply the equations to calculate a seismic response coefficient (Cs) that is used to calculate the seismic base shear, which is used to size the seismic resisting elements of the building. However, many do not understand the background behind the equations and the coefficients.

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Although pile caps are an important structural element, they are generally neglected in textbooks on structural design. This article is intended to offer a brief introduction to the new CRSI/DFI (Concrete Reinforcing Steel Institute/Deep Foundations Institute) Pile Cap Design Guide referred to henceforth as the Guide. The Guide was authored by Dr. Timothy W. Mays, P.E. with The Citadel.

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Elevators in high-rise buildings are a necessity. They move people without noticeable waits, transport staff and materials, complement the building design, and enhance the building’s market reputation. Elevators must operate safely and seamlessly.

When buildings are designed, architects enlist the assistance of elevator specialists to determine the proper number, grouping and type of elevators. This approach ensures adequate capacity and provides appropriate waiting times without providing too many elevators.

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Hot-dip galvanizing provides a cathodic, barrier, and zinc patina protection of structural steel from corrosion. Structural steel put through the hot-dip galvanizing process goes through a series of chemical cleaning steps leading up to the final step of being completely immersed in an 830° F bath of molten zinc.  The heat effect on the steel, the viscosity properties of the cleaning solutions and zinc, and the resultant metallic zinc coating, requires certain design parameters be met to ensure the steel after galvanizing performs precisely as the engineer intends it to.

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