Reconciling the 2018 IBC, ACI 318-19, and PCI’s 2019 Report

This is a follow-up to a previous STRUCTURE magazine article titled Rethinking Seismic Ductility (March, 2016). The previous article presented possible shortcomings associated with the International Building Code (IBC) prescriptive seismic design philosophy used for both auger cast piles and prestressed piles to contrast foundation ductility design with that used for other structural elements. It also provided a side-by-side comparison of design and performance issues associated with auger cast piles and prestressed piles. …

Truths and Insights on Under-Slab Insulations with Structural Implications

Lightweight and versatile, molded polystyrene foam is a common commercial building material that remains misunderstood. Frequently misidentified as Styrofoam, molded polystyrene products range from lightweight structural materials and insulations for commercial construction to packaging for electronics, medicines, and fragile payloads to Original Equipment Manufacturer (OEM) applications like garage doors, jet skis, RVs, and much more. …

When a major tornado happens, it is all over the news. And, every year, the average person may recall hearing about a dozen or so tornado events, if that. So it might be startling to know that, on average, the number of tornadoes that touch down each year in the United States, according to www.ustornadoes.com, is more than 1,200. …

The Original Mass Timber

As Architecture, Engineering, and Construction (AEC) decision-makers continue to explore new applications for mass timber products. Forest product innovators are applying decades of existing research toward the scaled commercialization of structural round timber (SRT). The authors of this article predict that rising demand for mass timber products is an enormous opportunity for accelerating the use of SRT columns, spanning members, and trusses. …

The Impact of Deferred Submissions and Cost Silos

Component Manufacturers (CMs) are often a misunderstood business in the construction industry, specifically by the structural engineering community. CMs are a key supplier of load path resisting structural elements. Premanufactured roof trusses are one such element. Typically, the process of developing both the architectural and structural plans for a building designates “trusses by others.” By definition, trusses then become a deferred submittal. Given that trusses are the primary structural framework that provide resistance to the load path as load flows from the roof to the walls and floors to the walls and foundation, the concept of trusses being a deferred submittal presents both engineering and communication challenges. …

Lateral System Innovation for Today’s Construction Challenges

The millennial mindset is saving our profession. A common question from young engineers – “Why do we do things the way we do them?” – can be just as off-putting to us as it is to the Baby Boomer down the hall. The more experienced engineers often side with Gen-Xer points of view and the played-out stories of rotary phones, record players, and the lost art of hand-drafting. All we want to say is: “because we do.” …

A Basic Primer

Fiber-reinforced polymer (FRP) composites are engineered to resist corrosion and provide high strength-to-weight and modulus-to-weight ratios compared to steel and concrete. In simplest terms, a composite material is produced when two or more substances are combined to take advantage of their unique strengths while overcoming their weaknesses. The first use of composite materials can be traced back to 1500 B.C. where Egyptians and Mesopotamians mixed mud and straw to create strong buildings. In the 1900s, the development of plastics birthed synthetic resins. Owens Corning introduced the first glass fiber combined with polymer resins. Following WWII, composites made their way into cars, airplanes, and boats, among other things. …

Something Old and Something New

Mass timber is not a new idea, just a new name. Many people have heard the term “mass timber” batted around in the last few years, but not everyone has a clear understanding of what it means. Mass timber used to be referred to as “heavy timber” and the International Building Code (IBC) classifies it as Type IV construction. …

As the building industry forges ahead with technology and innovation, designers are encouraged to develop structures that perform as never before possible. Particularly in zones of high seismic activity, structures with large open spaces and high ceiling heights may not have seemed practical before the introduction of systems such as multi-tiered braced frames (MTBF). However, specific requirements for designing these MTBF systems are now defined in the Seismic Provisions for Structural Steel Buildings, ANSI/AISC 341-16, referred to as the 2016 AISC Seismic Provisions. This provides support both for these structures and for the seismic design industry. …

Practical Applications and Considerations in Light-Frame Construction

Premanufactured, metal plate-connected, wood drag trusses can provide a pathed load-delivery mechanism designed to assist and engage the lateral force-resisting system (LFRS) elements during high-wind or seismic events. …