The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Coupled simulation of loading and response of columns under extreme events
Author:	Allahverdi, Navid H.
View Online:	njit-etd2010-083 (xiii, 140 pages ~ 10.0 MB pdf)
Department:	Department of Civil and Environmental Engineering
Degree:	Doctor of Philosophy
Program:	Civil Engineering
Document Type:	Dissertation
Advisory Committee:	Saadeghvaziri, M. Ala (Committee chair) Bukiet, Bruce G. (Committee member) Hsu, C.T. Thomas (Committee member) Rao, I. Joga (Committee member) Wecharatana, Methi (Committee member)
Date:	2010-05
Keywords:	Column response Extreme events Coupled simulation
Availability:	Unrestricted
Abstract:	Forces imparted to structural columns during blast-induced loading depends on the shape and size of columns as well as on the intensity of the blast. Column's geometry - i.e., shape and size - influences the flow field around the column and consequently the flow field determines forces experienced by the column The main objective of this research is to estimate the forces imparted to columns in a blast event through studying the air flow field around columns In this study, the physics of shock wave reflection and rarefaction waves are reviewed with application to describing the air flow around columns with circular and square cross sections. Then, simulations will be performed to determine the flow field around columns with different geometries. Based on the simulation results, force and impulse experienced by columns with different cross-sectional shapes and varying sizes are estimated. Finally, through curve-fitting techniques, correlations of variables are investigated and proper equations are proposed to estimate the force on columns based on shape, and size for a range of blast intensities. Also, it is attempted to approximate the response of columns with an equivalent single-degree of freedom (SDOF) model. The parameters of the equivalent single-degree of freedom are calibrated via simulation results. Due to the relatively short duration of blast loading in comparison with columns' natural period, column responses are mainly impulse-sensitive. The proposed equations in conjunction with SDOF model can be beneficial tools in blast design practices. Furthermore, the damage and failure modes of columns are studied. For columns that prove insufficient, the efficacy of retrofitting measures such as steel jackets have been investigated.