Cranes - The Sky is the Limit

IN THE SKY ABOVE

We Reach High . . .?

Do you also appreciate seeing a skyline replete with countless cranes? There is something thrilling about it – a bit daring, energizing, awe inspiring. To see the boom, a vertical column peeking above our cities – and, the jib reaching out above the vista is, to me, emotive and unforgettable.

The wise man should restrain his senses like the crane and accomplish his purpose with due knowledge of his place, time and ability ~ Chanakya

Cranes come in many shapes and sizes. Their uses, however, are universal. Hoist. Move. Repeat. Our thanks to the Mesopotamian’s original pulley system in 1500 BC, enhanced in 515 BC by the Greek’s, and engineered by Archimedes circa 287 BC – materials, equipment, cargo that otherwise would remain grounded are well managed. To keep this purpose simple it takes kinetic engineering knowledge, dedicated experience, and constructability ways and means,?all brought to bear with the goal of a safe and successful process – what Thornton Tomasetti’s Crane Engineering Team accomplishes daily. Conversely, when things don’t quite go as planned, we take these same abilities, expertise and lessons learned to help manage and mitigate your challenge.

With cranes, we continue to reach high, to achieve a sense of place – throughout time, majestically into our future.

JOELLE NELSON, PE

Joelle Nelson joined Thornton Tomasetti in 2004. She has served as a testifying expert and has experience in the investigation of major structural collapses. Her areas of expertise include wind related failures and collapses of cranes and other temporary structures. She has designed and investigated structures with complicated wind conditions including open frame structures, a topic which she has authored papers. Her wind-related investigations consist of collapses due to hurricanes, thunderstorms, and tornadoes. She has experience with construction and crane engineering and has investigated major crane collapses in New York, Florida, and Toronto as well as failures of temporary and seasonal structures. Her design experience is extensive and includes the design and renovations of complex and historic structures. She serves on the ASCE 37 Wind Load Subcommittee and the committee for ASCE 37 Design Loads on Structures During Construction.

SENSIBLE RESTRAINT

I have investigated several major crane collapses and each collapse occurred as a result of a unique set of conditions, needing to be investigated and uncovered, no two alike. However, I have noticed running themes.

1. The high wind event failure of a tower crane. While there are many possible causes for a collapse in a high wind event, the most common is that the crane was designed to weathervane and has failed to weathervane. Weathervaning?is when the crane rotates freely and points in the predominant wind direction like a rooster weathervane on top of a barn. Among other reasons,?a crane may not weathervane if (a) the operator did not release the slew break, (b) the slew ring was poorly maintained or there was an obstruction at the bearing,?or?(c)?the crane is subject to?turbulent?wind flows common in dense urban environments.
2. Erection, Dismantle, and Jumping. Improper procedures and/or weather conditions during the erection, dismantle, jumping, or jackknifing of a crane is another common cause of collapse. Improper setup of a crane does not necessarily result in an immediate collapse and may occur only after many repeated cycles of use or under an extreme but not unanticipated condition. The reason for improper setup can be an error on the part of the user/erector but can also be attributable to poor documentation.?

Many different parties have a role in a crane installation. The crane owner, crane user, crane manufacturer, and crane engineer of record are often considered the primary suspects when something goes wrong. However, several other parties may need to be considered including the crane inspectors, erector, and previous owners and users. We help identify the root cause and the potentially liable parties.

ABOUT THORNTON TOMASETTI

An employee-owned organization of engineers, scientists, architects and other professionals collaborating from offices worldwide, we support clients by drawing on the diverse expertise of our integrated practices. We are committed to being a sustainable and enduring organization and the global driver of innovation in our industry. www.thorntontomasetti.com

EMERGENCY RESPONSE AND CRANE ENGINEERING

When something goes wrong, you need to know why, and how to get back to full function and use – effectively and efficiently.

Thornton Tomasetti partners with owners, developers, operators, government agencies, contractors, attorneys, insurers, manufacturers and design professionals to resolve every type of issue confronting you.

We investigate problems in the built environment and provide evidence-based solutions founded on rigorous science and physics. We have the in-house experts to deliver the answers you need:?Structural,?Architectural,?MEP,?Fire and?Process,?Site-civil, Vibration,?Sustainability and Resilience.

Our multidisciplinary professionals help clients mitigate design and construction issues of all kinds and work to prevent future problems. Decades of experience enable us to quickly generate hypotheses and evaluate them based on physical evidence, interviews and operational data.

Our team is always searching for better ways to investigate and analyze engineering and design problems and share our results. Our staff works closely with the firm’s?CORE groups?to develop new technology – such as simulation and visualization tools and data acquisition and processing?systems – that help us better serve you.

Through our?Edinburgh, Scotland, testing lab, we can delve into experimental mechanics and devise testing protocols for experimental verification.

The bottom line? When you work with Thornton Tomasetti, you will always have an expert you can trust to find the answer and explain it clearly.

For additional information:

Amy Phillips, Washington DC | [email protected] or 202.580.6316

www.ThorntonTomasetti.com