Earticle

Because of quite high tensile strength, economical and locally available; bamboo can be used as a natural retrofitting material for the strengthening of RCC beam. The performance of bamboo sticks are investigated in this paper as retrofitted material. Three set of RCC beams of same dimension (width 4", thickness 6" and span 5.5') are tested up to ultimate load by one point loading system as a simply supported beam. These beams are addressed as S-1(a), S-1(b), S-1(c), S-2(a), S-2(b), S-2(c), S-3(a), S-3(b) and S-3(c) according to their set. Beams S-1(a), S-1(b) and S-1(c) are made without strengthening. The Beams S-2(a), S-2(b), S-2(c) is subjected to one layer of bamboo sticks only the bottom surface of beam. And another three beams of S-3(a), S-3(b), and S-3 (c) are strengthened by one layer of bamboo sticks on three sides of beams. After that they are tested and a comparison has been made on cracking load, ultimate load and deflection between the beams of with and without bamboo. Also a graphical representation indicates difference between the sets of two strengthening system. From this paper we can understand that the beams of three side bamboo layer (repairing) give comparatively good performance.

세그먼트 설계시, 축력과 휨모멘트가 주로 고려되는 하중이다. 두개의 하중에서 축력이 모멘트 보다 상대적으로 매우 크기 때문에 전단면이 압축상태에 있으며, 이는 균열 폭을 줄이는 효과가 있다. 그러나 콘크리트 구조물의 사용성 검토에서 축력은 고려하지 않고 있기 때문에 설계는 사용성에 지배되고, 사용성을 만족시키기 위하여 소요 철근량을 증가시키게 된다. 본 논문에서는 축력이 세그먼트의 사용성에 미치는 영향을 시험과 단면해석을 통하여 분석하였다. 세그먼트에 대한 시험을 수행하였으며, 초기균열저항성능에 대하여 고찰하였다. 분석결과 사용성 분석에서 축력을 고려함으로서 더욱 합리적인 설계가 가능한 것을 확인할 수 있었다.

In the design of tunnel segment structure, axial and moment forces are considered as significant forces. Since axial force is much greater than moment force, the whole section of segment remains in compression. Therefore crack width can be reduced. But the axial force is not considered in criteria for serviceability check. This fact leads service condition more severe compared to ultimate condition and makes the required steel reinforcement increase to meet the serviceability criteria. In this study, the effect of axial force on serviceability of tunnel segment is evaluated, experimentally and analytically. Mock-up tests on segments with actual size were performed and investigated in terms of initial crack resistance. The evaluation proves that more comprehensive design could be achieved when the axial force is considered in the procedure for the serviceability check in design of tunnel segment.

In particle or short-fiber reinforced composites, cracking of the reinforcements is a significant damage mode because the broken reinforcements lose load carrying capacity. This paper deals with elastic stress distributions and load carrying capacity of intact and cracked ellipsoidal inhomogeneities. Three dimensional finite element analysis has been carried out on intact and broken ellipsoidal inhomogeneities in an infinite body under pure shear. For the intact inhomogeneity, as well known as Eshelby(1957) solution, the stress distribution is uniform in the inhomogeneity and non-uniform in the surrounding matrix. On the other hand, for the broken inhomogeneity, the stress in the region near crack surface is considerably released and the stress distribution becomes more complex. The average stress in the inhomogeneity represents its load carrying capacity, and the difference of average stresses between the intact and broken inhomogeneities indicates the loss of load carrying capacity due to cracking damage. The load carrying capacity of the broken inhomogeneity is expressed in terms of the average stress of the intact inhomogeneity and some coefficients. It is found that the broken inhomogeneity with higher aspect ratio still maintains higher load carrying capacity.