본 연구에서는 비틀림 설계가 되지 않은 철근콘크리트 보의 비틀림 거동에 대하여, 폐쇄스터럽의 강도와 간격에 따른 거동 특성을 실험을 통하여 평가하였다. 그리고 비틀림 거동 시 폐쇄스터럽의 간격에 따른 종방향 철근의 거동특성을 분석 하였다. 실험결과 비틀림 설계가 되지 않은 철근 콘크리트 보의 경우 폐쇄스터럽의 강도는 비틀림 강도에 영향이 작은 것으로 나타났다. 그리고 비틀림 설계가 되지 않은 단면의 경우, 부재의 균열 비틀림 모멘트에 안전율을 고려하여 부재의 비틀림 강도를 간접적으로 평가할 수 있을 것으로 판단된다. 종방향 철근이 균열 억제 및 비틀림에 의한 인장력에 저항하기 위해서는 폐쇄 스터럽의 간격이 중요한 영향을 미치는 것으로 나타났다.

This study investigates the torsional behavior within the geometric range of the curved PSC bridge designed and constructed in the recent work. Compared with the design specifications for torsion on the Korean Highway Bridge Design Specification(2010), the reasonable torsional reinforcement design criteria are reviewed and proposed for curved PSC girder. A numerical study investigates the torsional behavior of a curved PSC box girder. From the study on the geometrical shape of the curved beam and the torsion caused by the eccentric load of the vehicle load in this study, the following results were derived: the design criteria for diaphragm and crossbeam as presented in the current Korean Highway Bridge Design Specifications (2010 & 2015) are based on the single PC box bridge applied by the FCM or ILM method, therefore the criteria is very conservative about the multi-box girder bridge type bridge in this study.

Experimental evaluation of torsional behavior, which is possible behavior of seismic beams of RC structures, was carried out. Concrete strength and stirrup spacing were set as experimental variables to investigate the torsional strength of RC beams. Based on the experimental results, the torsional strength of RC beams was compared and analyzed. From the experimental results, the concrete strength was caused a difference of about 30% in the torsional strength of the maximum torque of the RC beam specimen, and the stirrup spacing was found to be about 2.8 times and 5 times that of the peak torque. Therefore, this study will be an important study to understand the effect of both concrete strength and stirrup spacing for the torsional strength or torsional behavior of RC beams.

The need to consider torsion in the design of members of a structure has recently been increasing; therefore, many studies on torsion have been carried out. Recent research was focused on the torsional performance of concrete according to the reinforcing materials used. Of particular interest, are torsion studies of beams made of SFRC(steel fiber reinforced concrete), and there has been increasing use of SFRC at construction sites. In contrast, research on the composite PVA-ECC (polyvinyl alcohol-engineered cementitious composite) has only covered its mechanical performance, though it exhibits excellent tensile-strain performance (better than SFRC). Therefore, research on the torsion of concrete beams retrofitted using PVA-ECC is lacking. In this study, the behavior characteristics and performance of reinforced-concrete beams retrofitted by PVA-ECC was investigated experimentally. The experimental results show that the resistance to torsional cracking is increased by PVA-ECC. In addition, the strain on the rebar of the specimen was found to be reduced.

이 논문에서는 여러개의 비틀림보강재를 갖는 코아구조물의 비틀림거동을 구하기 위한 매트릭스 해석방법을 제안하였다. 몇가지의 가정을 토대로 등분포와 삼각분포, 그리고 구조물 상단에 집중 비틀림하중이 작용하는 경우에 대한 응력과 변위식들을 유도하였으며 비틀림각과 응력을 최소화하기 위한 보강위치를 추정하기 위하여 보강재의 위치를 이동시켜 가변서 위치변화가 코아의 비틀림거동에 미치는 영향을 분석하였다. 또한 본 이론해석의 신뢰성을 고찰하기 위하여 비틀림보강재가 설치된 해석모델틀을 토대로 본 이론에서 구한 응력과 변위를 MIDAS-GEN프로그램에 의한 결과와 비교하였고, 만족할 만한 결과를 얻었다. 비록 컴퓨터를 이용한 3차원해석이 일반적인 구조해석 방법으로 다가왔으나 비용과 시간이 많이 소요되므로 모든 경우에서 최적의 수단이 될 수는 없다. 본 연구에서 제시된 공식들은 초기 설계단계에서 비틀림하중을 받는 실제 코아구조물의 응력과 변위를 추정하는데 유용하게 사용될 수 있을 것이다.

This study investigates whether the crack torsional moment equation of the concrete structure criterion can be applied even when the criterion for the minimum torsional reinforcement amount and spacing is not satisfied. As a result of the experiment, it was found that when the interval of the closed stirrup is wide, it does not satisfy the crack torsion moment induced by the thin-wall theory. However, when the strength reduction factor of 0.75 is applied, the torsional moment criterion is satisfied. Therefore, it is considered that the torsional moment can be considered even if the criterion for the minimum rebar spacing is not satisfied.

In this study, an experiment was conducted to evaluate the behavior of fiber reinforced concrete beam according to GFRP(Glass Fiber Reinforced Polymer)sheets and based on previous specimens and directly compare the fiber reinforcing effect. As a result, all specimens, regardless of the cross section shape, had an increase in torsional capacity and similar behavior compared to previous study.

Time dependent finite element formulation for age-dependent torsional analysis of prestressed concrete flexural member was derived based on the time-independent finite element formulation. In the formulation, torsional creep was considered to predict torsion behavior of beam structure. Two-span prestressed double T-beam was analyzed to observe the effect of torsion creep.

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.