Date of Award

August 2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

Jian Zhao

Committee Members

Benjamin C Church, Todd Davis, Habib Tabatabai, Konstantin Sobolev

Abstract

An adhesive anchoring system usually consists of a threaded rod inserted into a drilled hole in concrete with adhesives such as epoxy acting as the bonding agent. The behavior of traditional adhesive anchors can be inconsistent because the bond on adhesive-concrete interface can be affected by many factors. It is known through laboratory tests and field studies that the bond strength of adhesive anchors can be adversely impacted by installation conditions, service conditions, and factors related to the adhesive material. While some factors are considered in the capacity equations in building codes and design guidelines, many other factors, especially those related to installation such as hole cleaning, must be addressed adequately in practice.

This study focused on an innovation for adhesive anchors that improves the robustness of adhesive-concrete interface such that the consistence of adhesive anchors can be improved. The innovation is about creating threads/grooves in drilled holes in concrete before the holes are filled with adhesive and anchors are installed. The hardened adhesive in the grooves fundamentally change the load carrying mechanism of the adhesive-concrete interface bond from shear adhesion to mechanical interlock. The new adhesive anchor system is expected to ensure robust connections with a reasonable increase in construction cost.

The new adhesive anchoring system was verified in this study using both unconfined and confined pullout tests in uncracked concrete. The tests were divided into to two groups, one on traditional adhesive anchors and the other on the new adhesive anchors, considering two anchor sizes and three hole-cleaning conditions that represent typical practices. The test results documented in this dissertation showed that the new adhesive anchors greatly improved the capacity and consistence of adhesive anchors. Finite element (FE) analyses using ABAQUS were also conducted to simulate the behavior of the adhesive anchors under the tensile load. The nonlinear analyses incorporating surface-to-surface contact, concrete damaged plasticity and nonlinear spring models were found suitable to capture the global and local behavior of the adhesive anchors with pullout bond failure.

While further studies are needed to verify the new adhesive anchoring systems under a variety of other conditions, this study indicated that the new adhesive anchors will help engineers to design/construct safe connections for a variety of connections. The application of the innovative anchoring system is expected to improve the capacity of adhesive anchors, to simplify construction procedures, to provide reliable anchoring systems and to improve public safety.

Download

Share

COinS