Civil Engineering

 

First Advisor

Christine E. Wittich

Second Advisor

Richard L. Wood

Date of this Version

5-2019

Citation

Devkota, K. (2019). "Full Scale 13-Story Building Implosion and Collapse: Effects on Adjacent Structures." MS Thesis, University of Nebraska-Lincoln

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor Christine E. Wittich & Professor Richard L. Wood. Lincoln, Nebraska: May, 2019.

Copyright (c) 2019 Kanchan Devkota

Abstract

Two dormitory halls at the University of Nebraska-Lincoln known as Cather and Pound halls were demolished via controlled implosion on December 22, 2017. Cather and Pound halls were two thirteen-story reinforced concrete structures. The demolition of these two structures included the implosion of controlled charges at selected columns on alternating floors which initiated the progressive collapse of these structures. Three nearby structures in the vicinity of Cather and Pound halls were instrumented with high sensitivity uniaxial piezoelectric accelerometers to record the response of the adjacent structures during the event of the implosion and the progressive collapse. While these two thirteen-story reinforced concrete structures were also instrumented with sacrificial accelerometers to record the real-time response of the structures during implosion and progressive collapse, the focus of this thesis is the responses observed at the adjacent structures during the demolition sequence. The primary objective is to understand how a group of nearby structures response and interact during the implosion and progressive collapse of multistory buildings. To this end, ground motion parameters at three free field positions nearby these adjacent structures have been quantified to observe the variation of free field ground motions during the demolition event. Likewise, the acceleration response data obtained from adjacent structures and free field positions have been analyzed in the time and frequency domains. The analysis of response data has also been presented separately in terms of the blast and collapse sequence to differentiate and understand the response of adjacent structures during the blast and progressive collapse of the two 13-story reinforced concrete structures. An input-output study of the responses observed within three adjacent structures with respect to the ground motion recorded at free field positions indicated that secondary effects, such as the air wave generated by the blast, contributed to the structural response. Two of the adjacent structures are numerically modeled with a lumped mass approach in LS-DYNA, and the responses of these numerical models are compared to the experimental recordings. The numerical study further emphasized the significance of the air wave.

Advisor: Christine E. Wittich and Richard L. Wood

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