Introduction and Scope of Work: HBM Engineering Group, in collaboration with Demtech, spearheaded the structural engineering services for the meticulous demolition of the U.S. Army Corps of Engineers gantry crane at Olmsted Dam. Our expertise covered comprehensive structural inspections, detailed structural analysis under various loads, verification of safety post-weakening, and the design of cables to ensure controlled falling post-blast.

General Structure Information: The existing gantry crane, spanning 150 feet wide, 115 feet tall, and 100 feet long, presented a complex structure with 4 girders and 8 supporting legs. Finite element analyses, utilizing SAP2000 Software, were instrumental in guaranteeing a secure and effective controlled demolition.

Demolition Procedure: Our meticulously crafted demolition procedure addressed the removal of non-structural elements, site clearance, and structural elements, including the precise cutting of girders and the implementation of weakening measures. Prior to demolition, access platforms were cut, and strategic holes were drilled for charges, ensuring a controlled and safe demolition process.

Structural Analysis: A rigorous structural analysis was performed to determine the structure’s adequacy under dead and wind loads. Four distinct cases were considered, including the structure in its original state, pre-blasting, pre-blast with cut sections and cables, and post-blast with separated columns. These analyses were crucial for understanding the structure’s behavior, ensuring safety, and planning a controlled demolition sequence.