Steel joists with flush framed end connections enhance floor vibration properties.

Recent floor vibration measurements and research completed by Vulcraft have shown that flush frame joist end connections can have a significant positive impact on a floor’s vibrational response when subjected to walking excitation. This article shows how the frequency and effective mass of the floor bay can be changed dramatically when switching from traditional bearing seats to flush frame connections developed by Vulcraft. Manual calculation procedures found in the American Institute of Steel Construction (AISC) Design Guide 11, 2nd Edition, Vibrations of Steel-Framed Structural Systems Due to Human Activity and the Steel Joist Institute’s (SJI) Technical Digest 5, Vibration of Steel Joist – Concrete Slab Floors (hereafter referred to AISC DG11 and SJI TD5) currently do not address steel joists with flush end connections. This article demonstrates how the provisions in AISC DG11 and SJI TD5 can be used for flush frame connections.

Fall from height represents one of the highest occupational hazards in general industry and at construction sites. Personal fall protection equipment is frequently used to abate this hazard as part of a fall arrest or travel restraint system, where the point of anchorage is a critically functional part of this operation. However, what is the role of the structural engineer in the overall design of fall safety systems? Proper understanding of structural implications and other design aspects is vital to the individuals who trust their livelihood each time they engage to a fall protection anchorage system.

The design of structures utilized to support fall protection systems (FPS) for workers at height is a topic that is often researched and questioned but is not a straightforward process. Unlike other common structures with design requirements such as loads, factors of safety, and minimum requirements defined in their respective codes and design guides, the design requirements for fall protection loads can be somewhat ambiguous. This article aims to provide a basic overview of FPS, define what regulations and standards exist in this space, and recommend a best practice approach for engineers to define strength requirements for fall protection anchorages.

Anchor Channels in Industrial Structures, Bridges, and Tunnels

Anchor channels with channel bolts enable the robust anchorage of components to reinforced concrete structures. State-of-the-art systems comprised of anchor channels and channel bolts, also commonly known as anchor channels, handle static, seismic, and fatigue loads in any direction. Installing components with channel bolts is fast and easy even under adverse conditions, where wind, water, and confined space entry restrict work activities, particularly with electrical equipment needed for welding, or when overhead installation may be too exhaustive for the installer due to long installation times.

Ductility is Critical

Undercut anchors are the ultimate post-installed anchor category as their load transfer mechanism is bearing, similar to that of headed studs cast into concrete. Tensile loads are transferred into the concrete employing an expansion sleeve driven over a cone into a cavity formed at the back of the drill hole. This mechanical interlock prevents the anchor from pulling out and results in high load capacities and small displacements. Undercut anchors typically show low sensitivity to extreme conditions like large crack widths. If they are made of steel with sufficient material ductility, undercut anchors show a high resistance against cyclic loading. When designed properly and with sufficient embedment depth, undercut anchors have high strength, stiffness, and ductility levels. The design of undercut anchors can also qualify them for ductile connections in seismic design. Their general robustness makes undercut anchors the preferred choice for critical connections where high load demands are to be transferred into the concrete safely (Figure 1).

Proper design of bearing intersections between mass timber members is critical to the overall success of a mass timber project. The details of these intersections have a significant effect on cost and schedule. This article focuses on the multi-story column condition, where loads from the column above need to be transferred down through the beam-column intersection, and the beams are supported using a bearing pocket instead of a bearing hanger (Figure 1).

Member and Connection Design Considerations

As architects, owners, and contractors continue to push the limits of wood-framed residential construction, manufacturers have responded by providing an increased number of specialized wood and connector products. However, in addition to specialized wood products, these same complex residential projects increasingly rely on reinforced concrete and structural steel to achieve the intended design, frequently necessitating custom connections. This article reviews the various wood products available today for framing floors and roofs and discusses connection considerations to wood, steel, and reinforced concrete.

Corrosion of metals used in construction is an age-old problem, one with annual costs exceeding $300 billion today in the United States alone. In addition to economic losses, corrosion of structural and non-structural elements creates a significant safety risk, particularly with critical connections. Fortunately, technologies have been developed to help address many of the causes of corrosion of these connections with effective products and processes.

Cross-Laminated Timber (CLT) panels are commonly used in mass timber structures. As with any structural element, proper detailing of the connections is crucial. Structures with practical connection details are usually cost-efficient and easy to fabricate and assemble. In contrast, poorly conceived connection details often result in an overly costly structure plagued with difficulty.