With the 2017 hurricane season coming to an end Harvey, Irma, Jose, and Maria affected large parts of the USA and Caribbean. Examples of roof uplift can be found in numerous structures. If a roof is not properly tied down the entire roof structure can be blown away as in this photograph from St. Thomas.
During Hurricane Wilma a tower crane at a high-rise condominium construction site in Hallendale, Florida suffered a collapse. The building, a 28 story concrete structure, is situated between the Atlantic Ocean and Route A1A, and was under construction at the time of the collapse. The crane was situated on the west side of the building and was connected to the building at the tenth and twentieth floors. The crane was over 300 feet tall. The crane broke at the twentieth floor; the top of the crane fell to the ground while the lower portion was damaged but remained attached to the building. CCA was requested to review the circumstances of the collapse of the crane and provide opinions as to the cause.
Records indicate that more than a half dozen cranes collapsed in southeast Florida during Hurricane Wilma in 2005. During Irma, in 2017, per news reports, 2 tower cranes collapsed atop one high-rise building in Miami.
Construction cranes have historically been designed to comply with the requirements of standard FEM 1.001 published by the Fédération Européenne de la Manutention. Because of the failure of several cranes, including those in south Florida, some engineers now believe that this standard is not sufficient with regards to hurricane wind speeds common to the region.
Current guidance on the design and installation of construction tower cranes can be found in ASME B30.3 published by The American Society of Mechanical Engineers. In addition to obvious considerations such as high winds and heavy loads, the designer of the crane must also contend with issues such as wind turbulence, vortexes, and buffeting. Cranes are re-used from one construction project to the other. As such, older cranes have been designed to earlier standards and may not be suitable along a hurricane coastline. Older cranes are also subject to corrosion and fatigue cracking and must be inspected regularly. The American Society of Civil Engineers publishes wind loads in ASCE 37 Design Loads on Structures During Construction.
Historically devices such as cranes which are used temporarily during construction have not been well regulated. Cranes are part of the means and methods of constructing a high rise building and as such are under the control of construction forces, not the design engineers. This crane collapse caused damage to the building under construction, damage to adjacent buildings and blocked a critical roadway during an emergency. Fortunately, there were no loss of life or injuries due to this crane collapse. However, adjacent buildings were occupied during the hurricane and injuries could have occurred. Construction professionals need to be vigilant about crane safety during hurricanes.