Yong-Jun Lee

Bond Behavior of RC Beams with Electric Arc Furnace Oxidizing Slag Aggregates

Abstract Electric arc furnace (EAF) slag is a by-product of steel production. Because the amount of slag produced is increasing each year, there is a growing need for effective methods of recycling this material. In this study, simple beam tests proposed by Ichinose were carried out to estimate the bond performance of reinforced concrete beams with EAF oxidizing slag aggregates. The main test variable was the type of aggregate used. A total of four specimens were designed to estimate the bond properties of top and bottom bars for the concrete. The bond test results revealed that the specimens with EAF oxidizing slag aggregates showed better bond performance than the basic specimen with natural aggregates. Furthermore, the experimentally observed bond strength of the specimens was compared with the theoretical results obtained from existing formulas. Consequently, the analytical results considering the effect of transverse reinforcement showed reasonable agreement with the experimental results.

Flexural Behavior of Reinforced Concrete Beams with Electric Arc Furnace Slag Aggregates

Abstract This study estimates the flexural performance of reinforced concrete (RC) beams with electric arc furnace (EAF) oxidizing slag aggregates. EAF oxidizing slag is a byproduct of steel production. It is composed mainly of CaO and SiO2, which are similar to the chemical properties of natural aggregates. Simply supported RC beams having various types of aggregates were tested to evaluate the applicability of EAF oxidizing slag as a concrete aggregate. The moment-curvature relationship and crack patterns up to peak load as well as the effective moment of inertia and deflection of the specimens under service load were analyzed and compared with the experimental results of natural aggregate specimens. The experimental results showed that the specimens with EAF oxidizing slag aggregates exhibited similar flexural performance to that of the specimens with natural aggregates.

Flexural Performance of Reinforced High-Strength Concrete Beams with EAF Oxidizing Slag Aggregates

This study evaluates the flexural behavior of reinforced high-strength concrete beams with electric arc furnace (EAF) oxidizing slag aggregates. The main test parameters include the type of aggregates, compressive strength of concrete, and tension reinforcement ratio. A total of eight simply supported beam specimens subjected to four point loads are cast and tested in flexure. Two types of aggregates, natural and EAF oxidizing slag aggregates, are used in this study. The compressive strength of the concrete is designed to have normal- and high-strengths of 24 MPa and 100 MPa, respectively. The tension reinforcement ratios of beam specimens are 0.3 and 0.5 times the balanced reinforcement ratio for flexure. The experimental results indicated that the flexural strength of specimens was not affected by the type of aggregate, whereas the flexural ductility of specimens with EAF oxidizing slag aggregates was superior to that of specimens with natural aggregates, regardless of the compressive strength of concrete and the tension reinforcement ratio.

Experimental Study on the Bond Capacity of RC Beams Using Electric Arc Furnace Oxidizing Slag Aggregates

Dept. of Architectural Engineering, Kongju National University, Cheonan 330-717, KoreaABSTRACT An amount of electric arc furnace slag, by-products generated in iron manufacture, is being increased. Therefore,it is required to recycle the electric arc furnace slag. Currently, it is possible to use the electric arc furnace slag as the aggregatesof the concrete through the insurance of volume stability but not in the past because of the expansibility of f-CaO and f-MgO. Inthis study, simple beam tests via Ichinose method were performed to estimate the bond properties of reinforced concrete (RC) beamsusing the electric arc furnace slag. The results of the test showed that the showed that specimens using the electric arc furnace oxi-dizing slag aggregates have similar or more bond capacity relative to the specimen of natural aggregates. Especially, bond capacityof the specimens using the slag aggregates was almost one and a half times higher than a specimen using natural aggregates.Keywords : electric arc furnace, oxidizing slag, slag aggregates, aggregates for concrete, bond capacity

A Prediction Model for Bond Deterioration in RC Members. I: Bond Stress-Slip Behavior for Splitting Failure

AbstractThis study proposes a model to predict bond stress-slip behavior by conducting tests on RC members that experience splitting bond failure when subject to cyclic loading such as seismic load...

Applicability of electric arc furnace oxidising slag aggregates for RC columns subjected to combined bending and axial loads

Abstract This study evaluates the applicability of electric arc furnace (EAF) oxidising slag as a concrete aggregate for structural members. The test variables are designed to the types of aggregates and axial loads. A total of six reinforced concrete columns subjected to reversed cyclic antisymmetric moment are tested in flexure. From experimental results, flexural strength of specimens with EAF oxidising slag aggregates is similar to that of specimens with natural aggregates regardless of axial loads. Furthermore, it can be founded from test results that ductility capacity of slag aggregate specimens is superior to that of natural aggregate specimens.

A Prediction Model for Bond Deterioration in RC Members. II: Bond Failure after Flexural Yielding

AbstractReinforced concrete (RC) structures are designed in such a way that flexural yielding precedes bond failure, in order to ensure the ductile behavior of members. When subject to cyclic loadi...

Flexural behaviour prediction for RC beams in consideration of compressive stress distribution of concrete with electric arc furnace oxidising slag aggregates

Abstract Research on the efficient utilisation of electric arc furnace oxidising slag, a by-product of the steel industry, is necessary as it is similar to natural aggregates in terms of chemical composition. The slag is also being produced in increasing amounts every year. This study performed flexural experiments on simply support beams with aggregate type and examined their concrete compressive strength, tension reinforcement ratio and compressive reinforcement ratio as variables to assess the effects of compressive stress distribution of concrete with electric arc furnace oxidising slag aggregates on the flexural behaviour of reinforced concrete beams. Compared to specimens with natural aggregates, electric arc furnace oxidising slag aggregates showed a smaller deflection before the yielding of tension reinforcement and ductile behaviour after yielding due to differences in compressive stress distribution. In addition, the proposed equations for the equivalent rectangular stress block parameter were found to provide more accurate predictions than the criterion used by other countries.

Structural performance of composite double beam system

A new composite structural system that is able to enhance constructability and is suitable for realization of long-span structures was developed. Steel beams, steel reinforced concrete columns, reinforced concrete drop panels, and slabs are placed in the system. To determine the structural performance of the system, the gravity and lateral load resisting properties of the system were investigated. It was found that the presence of a reinforced concrete drop panel at the top of a column brings about a reduction of the negative moment at the top of the column. Also, it was observed that a reinforced concrete drop panel on the top of the column significantly affected the deflection-control of the beam. In a lateral load resisting test, cracks in slabs of the new structural system disperse in a better manner than is the case for crack patterns in the conventional composite system. Also, via push-over analysis using a package of structural analysis software, it was found that the developed structural system is effective in the prevention of stress concentration in the column zone.

Flexural Behavior Evaluation of Reinforced Concrete Continuous Beams Using Drop Panel

This study evaluates the flexural performance of reinforced concrete (RC) continuous beams with double beam system (DBS). The DBS method with high-rigidity drop panels in beam-column joints can be expected to decrease the actual span of RC beams. To investigate the effect of drop panels, a total of nine RC continuous beam specimens with various rigidity and length of drop panels is cast and tested under monotonic gravity loads. As a result of test, the specimens with drop panels presented superior flexural behavior and lower deflection under service load compared to those of the specimens without drop panels. Furthermore, the specimens with drop panels showed smaller crack width under service load than compared specimens.