Identifier

etd-11082007-194406

Degree

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Document Type

Dissertation

Abstract

Techniques currently available to practicing engineers for estimating wind loads for petrochemical structures have little theoretical or experimental basis. This dissertation research is an effort to expand the understanding of wind effects on petrochemical and other, similar structures. Petrochemical structures introduce geometric scales into wind tunnel model simulations below what are common for enclosed structures. Wind tunnel experiments were performed to help determine whether this will introduce problems in achieving dynamic similarity between models and prototypes. The experiments did not reveal any clear indication that petrochemical structures cannot be modeled in wind tunnels at scales similar to those used for enclosed buildings. Aerodynamic coefficients were measured for models of open frame structures, partially clad structures, and vertical vessels in the LSU Wind Tunnel Laboratory. When possible, the values were compared with the literature or current analysis techniques. For open frames, diagonal braces and solid flooring had significant effects on the wind loads which are not reflected in current analysis methods. Shielding of equipment located within open frames was found to be underestimated by current analysis methods. Wind loads for partially clad structures exceeded those of enclosed structures with similar overall geometry for some cladding configurations. Wind loads for vertical vessels in paired arrangements were found to deviate significantly from wind load estimates for single vessels - a fact that is not represented adequately in current analysis techniques. When appropriate, recommendations were made to address the shortcomings in wind load analysis for these structures. An analytical model was developed to describe the variation of the wind force coefficient for higher-solidity open frame structures with respect to solidity ratio and plan aspect ratio. The model reproduced trends in experimental data from previous researchers and provided insight into the development of upper-bound wind loads for open frame structures. Experimental data was used to estimate the bias and variance of analytical estimates of wind force coefficients for petrochemical structures. Applying recommendations from this research reduced the variance in these estimates. The structural reliability of a petrochemical structure designed for wind loads according to current industry guidelines is only slightly lower than an enclosed structure.

Date

2007

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Marc Levitan

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