Document Type

Thesis - Open Access

Award Date

2020

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

First Advisor

Junwon Seo

Keywords

Adhesive, Aluminum, Connection, DMS, Statistical analysis, Strength

Abstract

The ultimate objective of this study was to determine the structural performance of the Dynamic Message Sign (DMS) bonded with chemical adhesive in terms of ultimate strength and fatigue strength. To achieve this objective, this study first investigated the effects of various parameters, including humidity and temperature on tensile, shear, peel, and cleavage strength through small-scale tests of adhesive specimens with variation in specimen width. The tensile, shear, peel, and cleavage specimens were conditioned in a temperature-humidity controlled chamber prior to its testing. The tensile, shear, peel, and cleavage specimens with different widths were tested according to American Society for Testing and Materials (ASTM) after conditioning them in different temperature and humidity conditions. Numerous data resulting from the tests were analyzed through graphical comparisons and statistical analysis, in order to explore the effect of the considered parameters on each of the strengths. As part of the statistical analysis, two separate regression models, Multiple Linear Regression (MLR) and Response Surface Metamodels (RSM), were developed. It was found that humidity and width were the most significant parameters negatively affecting the tensile and peel strength, respectively. The MLR and RSM regression models developed in this study can be used for the prediction of tensile, shear, peel, and cleavage strength of the adhesive joints for different temperature and humidity conditions that aid the design of adhesive joints in the DMS. Welded specimens were also tested at the same condition as in the adhesive specimen testing, and the results were compared with those from the adhesive testing. In addition to the small-scale tests, four full-scale DMS tests were performed to examine their structural performance. Specifically, the ultimate strength testing was carried out on one DMS with adhesive joints and one with typically welded connections, and the fatigue testing was also conducted for one DMS system with adhesive joints and one with welded connections. For the ultimate strength testing, a monotonic loading was applied to each DMS until failure, whereas for the fatigue testing, each of the DMSs were applied by a load of 0.818 kN equivalent to natural wind gust up to 500,000 cycles. The ultimate strength testing demonstrated that the adhesive DMS failed at 125 kN, while the weld DMS failed at 146 kN. During the fatigue test, stress ranges observed in the panel were much below the threshold of the aluminum panel of the DMS. No sign of damage was observed in both adhesive and welded DMSs from the fatigue tests. The results indicated that DMS with adhesively bonded connections is relatively better than welded DMS with respect to the stress induced in the aluminum panel.

Format

application/pdf

Number of Pages

280

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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