This study is based on developing a free-cement. The Setting time of 100% GGBS(Ground Granulated Blast furnace Slag) admixed alkali-activators is measured, the influence of cation of alkali-activators on setting time is assessed. As a result, in case of mixing KOH or NaOH, setting time is getting shorter, although, GGBS admixed Ca(OH)2 has similar setting times regardless of concentration of alkali-activators.

Mechanical splice sleeve has bee used to join the reinforcement rebar for transmitting stress effectively and guaranteeing mechanical performance of the reinforcement rebar which has been segmentally made. In this study, tensile strength of the embedded reinforcement rebar joined by splice sleeve were examined to evaluate the mechanical behavior and effect on tensile strength of the rebar joined by splice sleeve in the concrete member depending on rebar joining condition.

Construction of long span bridges is rapidly increasing, the criteria of impact load and study of stability for suspension bridge cables by rear-end collisions and crash of the vehicle, not at the moment is the actual situation. In this study, the main cable of suspension bridges was applied appropriate impact loads and analyzed the structural stability of the cable.

In this study, an experiment was conducted to evaluate the changes in the strength properties of cement paste by increasing the amount of added CNT. The results maybe useful to determine the proper amount of CNT considering the strength and fluidity of CNT-reinforced cement paste.

이 연구는 강섬유콘크리트를 사용하여 온도철근을 대체할 수 있는 가능성을 평가하기 위하여, 온도철근의 대체가 가능한 강섬유의 배합비를 결정하고 이에 따른 재료역학적 특성 및 경제성을 평가하였다. 강섬유는 길이 60mm, 직경 0.75mm를 사용하고, 배합비는 부피비로 0.2%, 0.5%, 1%를 사용하였다. 평가결과 강섬유 콘크리트가 강섬유의 혼입량과는 상관없이 일반 콘크리트보다 연성이 우수하고, 강섬유를 0.5% 혼입한 경우에는 온도철근을 배근한 경우보다 경제적으로 유리한 것으로 나타났다.

In the attempt to predict life time in a concrete, some modified pore structure in concrete was taken accounted to a diffusion modelling. As a result, total length coming from MIP and LTM methods was somewhat inconsistent with corresponding value from profiling. The reason was assumed that overestimated surface chloride content and penetration length with unaccurate determination of continuous pores.

The present study, a modified electrochemical treatment was applied to concrete to mitigate the leaching of alkali ions from concrete. The current ranged 500 mA/m2 and duration was 2weeks. Electrochemical treatment applied in concrete quantity of alkali ions leaching and the limit depth of concrete were decreased, through electrochemical treatment is very high inhibitory effect of the alkali ion is determined leaching.

The objective of this study is to develop a FRP Hybrid Bar for concrete structures, especially for marine and waterfront concrete structures. The purposes of hybridization are to increase the elastic modulus of GFRP bar with acceptable tensile strength. In this paper, using E-glass fibers and unsaturated polyester resins and steel wires, the FRP Hybrid Bar samples were pultruded and tested for tensile properties.

In this paper, we present requirements for the spudcan footing of jack-up barges, we take a survey about jack-up barges and their limitation. And by using the result of the survey, we find the failure modes and requirements for design of the footing.

In this study, it was developed hybrid fiber reinforced concrete using ground granulated blast furnace slag, the industrial wastes, and recycled aggregate. As a result of experiments on improvement of performances of eco-friendly buildings utilizing recycled resources (recycled coarse aggregates and ground granulated blast furnace slag), the following conclusions are drawn. As hybrid fiber(PVA Fiber+ Steel Fiber) was mixed with the concrete in which the replacement was conducted with recycled coarse aggregates and ground granulated blast furnace slag, the structural performance were increased.

This paper indicates seismic performance of wing walls using Engineered Cement Composite(ECC) for retrofit of non-ductile existing building. The specimens consist wing walls of different thickness. The specimens is tested cyclic lateral loads. The test results indicated that wing walls seismic performance of 100 mm thickness improved than 70 mm wing walls.

In this paper, in order to evaluate the seismic performance on semi-rigid column-tree type connections, the experimental results and the finite element analysis results were compared. As a results, both results were considerably similar.

In this paper, the seismic performance of column-tree connections was experimentally evaluated, depending on location of plastic hinge. As a result, although two specimens were qualified for SMFs, beam-to-column connection and flange plate were detected the brittle fracture during 5% story drift ratio.

By reducing the cross-sectional area of the splice plates, the weak-axis column-tree connections which plastic hinge was forced into the splice connection were proposed in this paper. The main objectives of this testing was to investigate the semi-rigid performance of weak-axis column-tree splice connection.

In this paper, the effects of beam splice location on seismic performance of column-tree connections were experimentally and analytically evaluated. The study results showed very little difference between the results of analytical and those of experimental.

This paper proposes a new seismic retrofit methodology combined with glass fiber sheet (GFS) and non-compression X-brace system using carbon fiber (CFXB) for reinforced concrete buildings damaged in earthquakes. The result reveals that the retrofitting methodology(CR-1, CR-2) proposed in this study is more strengthen than non-retrofit methodology(CS-0) about maximum resisting force and maximum displacement.

In this study, rational prediction models for the effective compressive strengths of HSC corner and interior columns with intervening NSC slabs are developed. A structural analogy between HSC column-NSC slab joint and brick masonry is used to develop the prediction models. In addition, the aspect ratio of slab thickness to column dimension and the surrounding slab confinement effect are considered in the models. The proposed prediction model is verified by comparison with experimental results and various prediction expressions. As a result, with average test-to-predicted ratios of 1.00 for HSC corner columns and 1.09 for interior columns, the proposed equation provides superior predictions over all of the existing effective strength prediction approaches including KCI structural concrete design code(2012).

Traditional ancient tomb is blocked from outside air by the original role of the structure. However, recently at the structure has been excavated and robbed, it is in a state of being opened. It is not easy to prevent durability reduction of structure member according to the opened state. To this end, This study perforns the behavior characteristics evaluation according to durability reduction of traditional ancient tomb.

In this study, compressive behavior of form-block-wall was studied through prism test. In the experiment, main variables are the difference in mix design of block and strength of grout concrete. Experiment result showed that the prism strength of form-block-wall increased in proportion to the strength of grout and block. The initial stiffness in load-displacement curve varied corresponding to the difference of block strength in low strength of grout concrete while there was not a difference of it in the case of high strength of grout concrete.

A comprehensive formulation of the torsional behavior of prestressed concrete (PSC) girder is presented. It accounts for prestressing forces of the PS tendons non-symmetrically placed. The formulation is derived based on Vlasov’s hypothesis of considering warping displacement and geometrical relationship of the deflected and elevated PS tendons.