Raising the Bar for Testing and Quality Assurance

It is a familiar situation for anyone who has been involved in a masonry construction project. Things have progressed through design, bidding, and contracting, and are in the construction phase. One day, as part of the specified quality assurance program, a testing laboratory technician visits the job, samples materials, and takes them away for testing. Sometime later, usually after 28 days, the dreaded call is made – the materials are not compliant. The project shuts down, meetings ensue, and further evaluation, usually costly destructive testing, is performed. Finally, additional testing shows satisfactory results and the project resumes. However, this process has caused significant lost time and testing. …

How Can We Better Utilize Limited Resources?

Bridge inspection frequency is mandated by the Federal Highway Administration (FHWA) metrics in their National Bridge Inspection Standards (NBIS) and the Code of Federal Regulations. The mandate on a regular frequency of inspection is how we ensure safety. That said, we operate under the current reality of limited resources. …

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. …

Ultra-high-performance concrete (UHPC) is an emerging class of concrete characterized by ultra-high compressive strength, significant post-cracking ductility, and exceptional durability compared to conventional concrete. UHPC is usually distinguished from conventional or high-performance concrete based on its compressive strength, which can range from a minimum of 17,000 psi to more than 30,000 psi. In addition, it also often exhibits post-cracking tensile strengths over 1,000 psi, a more than ten-fold decrease in chloride diffusion rates compared to conventional concrete, and essentially no susceptibility to deterioration by freezing and thawing (Russell & Graybeal, 2013). Most UHPC is also self-consolidating. …

Practical Construction Detailing for 8-inch CMU Special Shear Walls

Certain types of special masonry shear walls require reinforcement hooks, typically 180 degrees, at the end of a masonry wall, but the cell dimension and grout clearance requirements can make installation problematic.  When this happens, using a three-dimensional (3-D) technique allows for practical detailing and construction of horizontal reinforcement end hooks to vertical reinforcement as required by code for special shear walls (The Masonry Society, TMS 402-16, Section 7.3.2.6(d)). …

Building Structural Monitoring

Codes of practice and standards for structural design have traditionally been regarded as the ultimate security for making sure that structures comply with requirements for safety. The advent of new technology and higher computing power allows engineering design to be supplemented by measurements of the actual performance of a structure during and after construction. This would allow for feedback to validate whether buildings are built as intended and to determine if existing buildings have acceptable levels of capacity. If done on a broad level, it would give insight into community resilience and ultimately allow poorly performing buildings to be identified prior to shock events. …

We, as structural engineers, often find ourselves confined by a situation we created for ourselves. We operate in a design environment with easy access to information, have the ability to collect and analyze extensive data, and have access to robust and reliable analysis and design software. Nevertheless, prescriptive codes and standards we have developed prevent us from fully leveraging these capabilities. As we face multiple goals for our designs – safety, economy, serviceability, sustainability, and robustness – we can be constrained to follow a prescriptive path to a solution that often does not optimally satisfy any of them. …

Towards the end of 2008, the New York City (NYC) Buildings Department (DOB) became aware that wind turbines had been installed on a couple of rooftops. The department is and has been firmly in favor of sustainable initiatives, but there were concerns these installations had insufficient engineering control. New York City’s high density of buildings and pedestrian traffic create a condition where any loose and free-falling piece of equipment may result in a severe accident. …

A Residential Architect’s Perspective

As more architects make the switch from two-dimensional CAD to BIM, structural engineers are faced with a similar decision as to whether or not it makes sense to adopt BIM.  Some structural engineers who design primarily in wood have taken longer to make the switch than those designing larger Type I, II or III projects where clients or architects require the work be done in BIM.  …

When a nationally-known organic food market arrived in my neighborhood, I was very excited. The store radiated an idiosyncratic “crunchy granola” vibe. Fresh flowers, a coffee bar, and a shoeshine station situated at the store entrance communicated the message that this market would be unlike any other. The youthful, hip staff seemed enthusiastic about their work, making eye contact and small talk at the register. …