*********************************
There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
*********************************
School of Civil and Environmental Engineering
Ph.D. Thesis Defense Announcement
Experimental Testing and Modeling Strategies of Carbon Fiber-Reinforced Polymer Blast Retrofits Using Steel Anchorage Systems
By
Genevieve L.F. Pezzola
Advisor:
Dr. Lauren Stewart (CEE)
Committee Members:
Dr. Gilbert Hegemier (UCSD-SE), Dr. Laurence Jacobs (COE), Dr. T. Russell Gentry (ARCH), Dr. David Scott (CEE)
Date & Time: Wednesday, April 25th, 2018 , 1:00PM
Location: Sustainable Education Building, 122
The ongoing presence and persistence of terrorist groups continually threaten the United States of America and its allies. This perpetual threat emphasizes the urgency to strengthen and retrofit any structural vulnerabilities, especially vulnerabilities that when exploited could lead to catastrophic damage of expensive infrastructure or loss of life. To avoid these losses, the application of fiber-reinforced polymer (FRP) laminates as a retrofit on reinforced concrete (RC) structural elements has been proven to increase the flexural strength and blast resistance. FRP has been the subject of many studies due to its high strength, stiffness to weight ratio, and ease of installation.
In these studies, it is often seen that the retrofit fails prematurely before rupturing in tension and reaching its full tensile strength. The premature failure most often observed is a debonding failure of the FRP from the concrete, but this failure rarely occurs in the adhesion layer. Anchorage devices can be utilized to improve the performance of the FRP retrofit. Several studies have been conducted to observe the performance of mechanical anchors, but there is limited research on mechanical anchorage systems.
As a part of this research effort, two test series were conducted to investigate RC slabs retrofitted with FRP and two different mechanical anchorage systems. One mechanical anchorage system used 17 small steel plates dispersed throughout the specimen and the other mechanical anchorage system consisted of three long steel straps placed at the mid-height and quarter points of the specimen that spanned the width of the specimen. The first test series utilized live explosives and investigated both anchorage systems. The second test series was conducted with four non-explosive blast generators and investigated the steel strap anchorage system further. The research concluded that the failure modes between the two different testing methods were very similar. Finite element analyses and SDOF methods using current approaches were developed.
The results of the two test series emphasized gaps in the literature about RC slabs retrofitted with FRP and mechanical anchors, which motivated the objectives of this dissertation. The first objective was to characterize the governing phenomena of the performance and failure of mechanical anchorage systems applied to FRP retrofits on RC slabs which was done by performing a spall analysis and timeline analysis of each slab tested. The second objective was to develop an analytical model that predicts RC slab behavior retrofitted with FRP and includes the presence of anchors and dynamic loading. A new analytical tool for a variety of blast scenarios and slab dimensions. The fourth objective was to validate the non-explosive blast generator as an appropriate means to test the response of RC slabs retrofitted with FRP subjected to blast loading. The blast generator was validated through computational analysis and a thorough comparison between the loading and behavior of the slabs in each test series.
