Jeong-Hee Lim

The Properties of Durability and Strength of Fiber-Reinforced Polymer-Modified Mortars Using Eco-Friendly UM Resin

ABSTRACT In this study, performance of fiber-reinforced polymer-modified mortar was studied for the development of eco-friendly materials for high performance repair and reinforcement. The general cement mortar and eco-friendly UM resin was mixed with a certain percentage for increased durability. To increase the strength of the polymer-modified mortar, PVA fiber, steel fiber and hybrid fiber were added at a constant rate. Hybrid fiber is contains the same percentage of PVA fiber and steel fiber . In order to determine the strength properties of fiber-reinforced polymer-modified mortar, the compressive strength test, the splitting tensile strength test and the flexural strength test were performed. And, in order to determine the durability properties of fiber-reinforced polymer-modified mortar, water absorption test and chemical resistance test were performed. From the experimental results, polymer-modified mortar using UM resin was improved durability. And the tensile strength and flexural strength increased, which were the vulnerability of fiber reinforced polymer-modified mort ar. From this study, fiber-reinforced polymer-modified mortar u sing eco-friendly UM resin can be used to repair and reinforcement for the external exposure of concrete structures to improve the durability.

Experimental Study on Torsional Behavior of RC Beam with High Strength Stirrup

In this study, the behavior of the reinforced concrete beams according to the strength of the stirrups and the spacing of the stirrups was evaluated through experiments. From the experiment results, the torsional strength was almost the same even if the strength of stirrup was as large as 20 %. When the spacing of the stirrups doubled, the maximum torsional moment was reduced by about 16 %. However, the twist angle at the occurrence of the maximum torsional moment increases by about 50 % as the spacing of the stirrup decreases. It is considered that the spacing of the stirrup increases the ductility behavior of the RC beam by increasing the number of effective stirrup in the torsional behavior of the RC beam.

Analysis of Nonlinear Torsional Behavior for High Strength Reinforced Concrete Structure Using 3-Dimensional Lattice Model

Because of earthquakes that have recently struck, seismic design criteria that considered performance of structure were included in the design concepts. Thus, a simple analysis tool is needed to predict the strength and ductility of RC structures. In this study, three-dimensional lattice model was developed to expand the two-dimensional lattice model. Torsional analysis of the structure was done to evaluate the developed three-dimensional lattice model. Lattice model was evaluated by comparing analytical results with experimental results. Lattice element size was evaluated using the results of analysis. Torsional analysis results, using three-dimensional lattice model, show that the results are relatively consistent with the experimental values.