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Author Archives : Natasha Zamani, Ph.D., P.E.
Natasha Zamani, Ph. D., P. E., is a registered Civil and Structural Engineer in Texas and serves as the Codes and Standards Senior Manager at Hilti North America. She can be reached at (Natasha. Zamani@hilti.com).
Composite floor deck construction has become very popular. It combines structural efficiency with a speed of construction that offers an economical solution for a wide range of building types, including commercial, industrial, or residential buildings. Composite slabs consist of profiled steel decking with an in-situ reinforced concrete topping. The decking not only acts as a permanent formwork to the concrete but also provides sufficient shear bond with the concrete so that, when the concrete has cured, the two materials act together compositely to resist the loads on the deck. …
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Concrete and masonry members can experience cracking due to their low tensile strength. Cracking can occur for a variety of reasons, including loads, shrinkage, temperature, settlement, or stresses induced by seismic and wind activity. Figure 1 shows diagonal cracks in masonry walls caused by an earthquake. Since cracks can have a significant negative impact on anchor performance, the assumption that an anchor is situated in a crack is not conservative, especially during seismic behavior. For concrete members, building codes require the structural design to address the effects of cracks on post-installed and cast-in-place anchors. Anchors must be evaluated and the structural designer must determine design data. However, for masonry members, there is no provision for considering the impact of cracks on anchor performance. This article presents the results of an experimental program addressing testing and evaluation of anchorage performance in cracked masonry. …
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Headed cast-in specialty inserts are internally-threaded steel shell elements welded to a bearing plate that is cast into concrete members. Hilti’s KCM and Simpson’s Blue Banger Hanger anchors are some examples of headed cast-in specialty inserts (Figure 1). These anchors are used to attach structural and non-structural components. In general, the American Concrete Institute’s (ACI) Building Code Requirements for Structural Concrete (ACI 318) provides design requirements for cast-in anchors in concrete. However, the wide variety of shapes and configurations of specialty inserts make it challenging to prescribe generalized tests and design equations. Hence, they have been excluded from the scope of ACI 318. …
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