In this study, the static load test and the load transfer test were carried out to evaluate the structural performance of the circular anchorage proposed by the previous study. Specimens were fabricated according to KCI-PS101 and ETAG 013. As a result of the static load test, it was verified that the displacement of the wedge and the strand was kept constant when the tensile force of 80% of the nominal strength of the strand was applied. In the load transfer test, it was confirmed that all the specimens satisfied the stabilization formula of KCI-PS101 and ETAG 013. Post-tensioned one-way slab with circular anchorage were fabricated to evaluate the flexural behavior. All specimens exhibited the same flexural behavior and maximum load. However, the specimen with circular anchorage were advantageous than the rectangular anchorage one in terms of crack control of the anchorage zone.

최근 국내에서는 고층 벽식 아파트 건설 시, 하부 주차공간과 공용공간 확보를 위하여 RC 전이슬래브 시스템을 사용하는 경우가 증가하고 있다. 하지만 두께가 얇은 RC 무량판 슬래브를 위해 개발된 설계방법 및 구조성능평가 방법을 두께가 매우 두꺼운 전이슬래브 구조설계에 그대로 사용하고 있다는 문제점이 있다. 따라서 합리적인 전이슬래브의 구조설계를 위해서는 RC 전이슬래브 시스템의 2면 전단거동 양상에 대한 명확한 분석이 필요하다. 이에 따라 본 연구에서는 전이슬래브의 두께, 콘크리트 강도, 전단경간비, 철근비 등 다양한 설계변수에 따라 비선형 FEM을 이용하여 전이슬래브의 2면 전단거동을 분석 하였다. 또한 비선형 FEM 해석결과와 기존의 2면 전단강도 평가식으로 예측한 전단강도를 비교분석하여 기존 평가식의 전이슬래브 2면 전단강도 평가 유효성을 검토하였다.

PURPOSES : The purpose of this study was to investigate the behaviors of the middle slab in a double-deck road tunnel subjected to construction equipment loading from such as a concrete pump car, concrete transmixer, and lifting crane. METHODS: The major construction processes of a middle slab include concrete placement, concrete transportation, and lifting of materials near the emergency passageway section. During the concrete placement, the middle slab is subjected to construction loading due to the presence of the concrete pump car and fully loaded concrete transmixer. During the concrete transportation, the middle slab is subjected to loadings from both the fully loaded and empty concrete transmixer. The emergency passageway section of the middle slab is subjected to crane loading during lifting work. The magnitudes and geometries of these construction loadings are determined and the stresses and deflections of the middle slab under these loadings are analyzed using finite element models of the middle slab. The behaviors of the middle slab under the design truck loadings are also analyzed to compare the results with those under construction loadings. RESULTS : The stresses and deflections of the middle slab under construction loadings are comparable to those under the design truck loadings. Higher stresses can be observed when the concrete transmixers cross paths at the expansion joint section of the middle slab. The behaviors of the middle slab under the construction loadings during concrete placement are very similar regardless of the section types of the middle slab such as the normal, expansion joint, and emergency passageway sections. CONCLUSIONS : When the middle slab is designed, the construction loadings should be considered to determine the primary design loads and to verify the usability of a variety of construction equipment.

The objective of this study is to analyze the behavior and failure mode of the brackets that support middle slabs in the double-deck tunnels by conducting laboratory experiments. In the double-deck tunnels, the middle slabs are supported by the brackets connecting to the tunnel lining. The brackets are subjected to the loads due to the weight of middle slabs and traffic moving on the middle slabs. Since the damages of brackets are directly associated with the safety problems such as falling down of middle slabs, the appropriate design of brackets is one of the most important factors when designing double-deck tunnels. In this study, the reinforcement design of concrete bracket was performed based on the concrete structure design guide, and the load capacity was evaluated by conducting laboratory loading tests. A small scale concrete bracket specimen was fabricated using the scale factor of 0.5. The reaction wall is normally needed to simulate the tunnel lining in this kind of test; however, two brackets were attached symmetrically to a column, which was assumed to be tunnel lining, to be able to conduct the tests without using the reaction wall. When the bracket specimen was fabricated, the lining part was fabricated first and after curing of the lining part, two brackets were fabricated at the same time at both sides of the lining part. In the tests, the loads were applied to both brackets simultaneously using a loading frame and the displacements were measured at different locations. The main behaviors of the bracket systems such as the vertical displacements of brackets and the displacements at the interfaces between the brackets and lining were measured and the horizontal displacements of the specimen were also measured at the bottom of the lining part to confirm if there was any slip or rotation of the specimen during the tests. The experimental analysis results showed that the initial damage of the specimen was observed at the interface between the bracket and lining with appearing the gap and the failure of the specimen was reached with cracking in the brackets. The load capacity (safety factor) of the bracket specimen to the initial damage based on the design load was 2.5 and to the failure was 3.3.

PURPOSES : The purpose of this study is to investigate the stresses of the middle slab in a double-deck tunnel owing to the slab lift to replace the underlying elastic pads during maintenance workMETHODS: The middle slab was divided into three different sections: typical section, expansion joint section, and emergency passageway section. Finite element analysis models of these three sections of middle slab were developed, and the stress distribution and maximum stresses were obtained using the models when the middle slab was lifted to replace the underlying elastic pads. Various slab lifting methods were examined in this study such as one-, two-, and multiple-point lifts, distributed lifts, and one or both slab side edge lifts.RESULTS: When the slab side edge is lifted, the longitudinal stresses of the slab are almost the same as the principal stresses. This implies that the governing stresses are the longitudinal stresses. The maximum stresses with both-edge lifts are generally smaller than those with one-edge lifts at all three sections of middle slab.CONCLUSIONS: If the middle slab in a double-deck tunnel is lifted for maintenance, the slab should be lifted at multiple points along the longitudinal direction to reduce the tensile stresses.

Dynamic numerical simulation of pile-supported slab track system embedded in a soft soil and embankment was performed. 3D model was formulated in a time domain to consider the non-linearity of soil by utilizing FLAC 3D, which is a finite difference method program. Soil non-linearity was simulated by adopting the hysteric damping model and liner elements, which could consider soil-pile interface. The long period seismic loads, Hachinohe type strong motions, were applied for estimating seismic respose of the system, Parametric study was carried out by changing subsoil layer profile, embankment height and seismic loading conditions. The most of horizontal permanent displacement was initiated by slope failure. Increase of the embedded height and thickness of the soft soil layer leads increase of member forces of PHC piles; bending moment, and axial force. Finally, basic guidelines for designing pile-supported slab track system under seismic loading are recommended based on the analysis results.

RC 플랫 플레이트 시스템은 공기단축, 시공성 향상, 층고 절감 등의 장점이 있으나, 장스팬 적용 시 슬래브의 작은 휨강성 으로 인해 균열 손상 및 과다 처짐이 발생하는 경향이 있다. 특히, 시공 중 슬래브 자중에 의한 과하중의 작용이 슬래브의 장단기 처짐을 증가시킬 수 있다. 이러한 문제점은 자중 저감이라는 장점을 갖고 있는 중공 슬래의 사용을 통해 해결할 수 있다. 이 연구에서는 슬래브 처짐에 대한 중공 슬래브의 자중저감 효과를 분석하기 위하여 변수연구를 수행한다. 콘크리트 강도, 슬래브 시공주기, 동바리 지지층수, 압축철근비, 인장철근비 등의 변수조건들을 포함하여, 시공단계, 콘크리트 균열, 장 기 효과를 고려한 시공하중 및 처짐을 산정한다. 일반 슬래브와 중공 슬래브에 대한 시공 중 단기처짐과 완공 후 장기처짐을 비교하고, 슬래브 처짐에 대한 중공 슬래브의 효과를 분석한다.

PURPOSES : The purpose of this study is to investigate the fundamental behaviors such as stresses and deflections of the middle slab in a double-deck tunnel for the development of a middle slab design guide. METHODS : The middle slab has been divided into the following three different sections as according to its structural differences: the normal section, expansion joint section, and emergency passageway section. The normal section of middle slab represents the slab supported by brackets installed continuously along the longitudinal direction of tunnel lining. The expansion joint section refers to a discontinuity of middle slab due to the existence of a transverse expansion joint. The emergency passageway section has an empty rectangular space in the middle slab that acts as an exit in an emergency. The finite element analysis models of these three sections of middle slab have been developed to analyze their respective behaviors. RESULTS: The stresses and deflections of middle slab at the three different sections decrease as the slab thickness increases. The emergency passageway section yields the largest stresses and deflections, with the normal section yielding the smallest. CONCLUSIONS: The stress concentrations at the corners of the passageway rectangular space can be reduced by creating hunch areas at the corners. The stresses and deflections in the emergency passageway section can be significantly decreased by attaching beams under the middle slab in the passageway area.

최근 콘크리트 궤도 슬래브 하면과 교량 바닥판 사이에 저마찰 슬라이드층을 형성하는 궤도 시스템인 슬라이딩 궤도와 관 련된 연구가 활발히 진행되고 있다. 본 연구에서는 슬라이딩 궤도에서 열차 주행에 따른 횡방향 하중을 저항하기 위해 설치 되는 횡방향 지지 콘크리트 블록의 전단 내하력에 대한 연구를 수행하였다. 횡방향 지지 콘크리트 블록의 전단 내하력 산정 을 위해 타설경계면에서의 콘크리트 마찰 및 철근의 다월 거동을 고려한 산정 기법을 개발하다. 제안된 산정 기법은 기존의 실험에서 측정된 전단 내하력을 13∼23% 정도 보수적으로 예측하는 것으로 나타났다. 이는 균열면 골재 맞물림 효과를 무 시한 것에 따른 것으로, 현장에서의 타설경계면 상태가 불확실한 것을 고려할 때 횡방향 지지 콘크리트 블록에 대한 안전측 설계를 위해 제안된 산정 기법이 합리적인 것으로 판단된다. 제안된 전단 내하력 산정 기법을 토대로 횡방향 지지 콘크리트 블록에 대한 설계 방안을 마련하였다

슬라이딩 궤도는 콘크리트 궤도와 교량 바닥판 사이에 저마찰 슬라이드층을 두어 레일신축이음장치와 같은 특수 장치를 적용하지 않고도 궤도-교량 상호작용 효과를 효과적으로 저감시킬 수 있는 새로운 궤도 시스템으로 개발되고 있다. 이 논문에서는 장경간 교량에 슬라이딩 궤도와 레일신축이음장치를 각각 적용한 경우에 대하여 궤도-교량 상호작용해석을 수행하고 그 결과를 비교 검토하였다. 대상교량은 상호작용 효과를 극대화하기 위하여 9경간 연속 PSC교와 2경간 연속 강합성교를 포함하며, 총 연장 1,205m, 최대 고정지점간 거리 825m인 장경간 교량을 선정하였다. 해석결과 슬라이딩 궤도는 레일신축이음장치를 적용한 경우보다 레일 부가 축력이 더 작은 것은 물론, 지점부에 재하되는 수평 반력 또한 작게 나타나 궤도-교량 상호작용 저감 효과가 뛰어난 것으로 확인되었다. 반면 슬라이딩 궤도는 온도하중에 의해 높은 슬래브 축력이 발생되므로, 궤도 설계 시 슬래브 축력에 대한 단면 설계에 주의를 기울일 필요가 있다.

The purpose of this paper is to demonstrate to the practicing engineers, how to apply the advanced composite materials theory to the slab bridges. For general construction material used, there is certain theoretical limit in sizes. For super slab bridges construction, the reduction in panel weight is the first step to take in order to break such size limits. For a typical slab bridges panel, both concrete and advanced composite sandwich panels are considered. The concrete panel is treated as a special orthotropic plate. Advanced composite sandwich panels are considered as a self-weights less than one tenth of that of concrete panel, with deflections less than that of the concrete panel. This conclusion gives good guide line for design of the light weight of slab bridges.

Star forming galaxies found in the early universe exhibit asymmetric Lyα emission line that results from multiple scattering in a neutral thick medium surrounding the Lyα emission source. It is expected that emergent Lyα will be significantly polarized through a large number of resonance scattering events followed by a number of successive wing scatterings. In this study we adopt a Monte Carlo method to calculate the polarization of Lyα transferred in a very thick static slab of Hi. Resonantly scattered radiation associated with transitions between 1S1 2 − 2P1 2 , 3 2 is only weakly polarized and therefore linear polarization of the emergent Lyα is mainly dependent on the number of off-resonant wing scattering events. The number of wing scattering events just before escape from the slab is determined by the product of the Doppler parameter a and the line center optical depth τ0, which, in turn, determines the behavior of the linear polarization of Lyα. This result is analogous to the study of polarized radiative transfer of Thomson scattered photons in an electron slab, where the emergent photons are polarized in the direction perpendicular to the slab when the scattering optical depth is small and polarized in the parallel direction when the slab is optically thick. Our simulated spectropolarimetry of Lyα shows that the line center is negligibly polarized, the near wing parts polarized in the direction parallel to the slab and the far wing parts are polarized in the direction perpendicular to the slab. We emphasize that the flip of polarization direction in the wing parts of Lyα naturally reflects the diffusive nature of the Lyα transfer process in thick neutral media.

UHPC(Ultra High Performance Concrete) is used widely with its remarkable performance, such as strength, ductility and durability. Since the fibers in the UHPC can control the tensile crack, the punching shear capacity of UHPC is higher than that of the conventional concrete. In this paper, seven slabs with different thickness and fiber volume ratio were tested. The ultimate punching shear strength was increased with the fiber volume ratio up to 1%. The shear capacity of specimens with the fiber content 1% and 1.5% do not have big differences. The thicker slab has higher punching shear strength and lower deformation capacity. The critical sections of punching shear failure were similar regardless of the fiber volume ratio, but it were larger in thicker slab.

PURPOSES: The purpose of this study is to investigate the relationship between the crack propagation depth through a slab and crack width movement in continuously reinforced concrete slab systems (CRCSs). METHODS : The crack width movements in continuously reinforced concrete pavement (CRCP) and continuously reinforced concrete railway track (CRCT) were measured in the field for different crack spacings. In addition, the crack width movements in both CRCP and CRCT were simulated using finite element models of CRCP and CRCT. The crack width movements, depending on the unit temperature change, were obtained from both the field tests and numerical analysis models.. RESULTS: The experimental analysis results show that the magnitudes of the crack width movements in CRCSs were related to not only the crack spacing, but also the crack propagation depth. In CRCP, the magnitudes of the crack width movements were more closely related to the crack propagation depths. In CRCT, the crack width movements were similar for different cracks since most were through cracks. If the numerical analysis was performed to predict the crack width movements by assuming that the crack propagates completely through the slab depth, the predicted crack width movements were similar to the actual ones in CRCT, but those may be overestimated in CRCP. CONCLUSIONS: The magnitudes of the crack width movements in CRCSs were mainly affected by the crack propagation depths through the slabs.

본 연구에서는 프리스트레스트 콘크리트 일방향 슬래브의 사용성 평가를 위한 처짐을 분석하기 위하여 유한요소법에 기반한 해석적 연구를 수행하였다. 유한요소 상용 프로그램을 이용한 해석결과와 실험결과를 비교하여 모델링의 타당성을 검증하였으며, 비교적 유사한 결과를 나타내었다. 또한, 콘크리트 압축강도, 편심 거리, 활하중, 그리고 긴장재의 배치형태에 따른 처짐을 분석하여 수계산 결과와 비교하였고, 회귀분석을 통해 변수들과 처짐 사이의 상관관계를 확인하였다. 그 결과, 콘크리트 압축강도가 클수록, 편심 거리가 클수록, 활하중이 작을수록 처짐이 감소하는 것을 확인하였으며, 직선형태의 처짐이 가장 작고 절곡형태의 처짐이 가장 큰 것을 확인하였다. 또한 회귀분석을 통해 콘크리트 압축강도와 편심 거리가 솟음값에 미치는 영향을 분석하였다.

An experimental study on the structural behavior of connection types between approach slab and integral abutment has been done for three typical bar connections. Typical hinge style reinforcing bar detail for its connection is preferred in order to accommodate rotation of the approach slab among engineers. However, the straight horizontal bars can be used as connection detail accomodate structural capacity. Total six specimens with three types of rebar detail are tested for direct tensile and bending load. The characteristic structural behaviors are carefully monitored and all the strain gauge data obtained are analyzed. It is shown that the structural performance of all the specimens well exceed its design allowance. Several design suggestions are given based on careful reviews on the experiment.

Main topics in this study is a new structural detail for connection between H-Steel or SRC column and flat plate slab. We carried out to evaluate the punching shear performance of H-steel or SRC column + RC slab system for vertical load and lateral load. From the test results structural characteristics - yield moment, yield rotation, maximum moment, deformation capabilities ect. - are obtained and evaluated. In this paper as a shear reinforcement for supporting region of plate closed stirrup type and shear band are used, and their test results are compared.

An experimental study was carried out to evaluate the punching shear performance of H-steel column + RC slab system for vertical load. Three specimens were constructed for interior column-slab system. All specimens were the same configuration and material properties except for columns such as RC column+flat plate slab and H-Steel column+flat plate slab. From the test results structural characteristics (maximum proof stress, maximum displacement, deformation capabilities and so on) are obtained and evaluated.

This study is for reduction of heat island to control the rise in climate, temperature changes, according to the passage of a vehicle due to cyclic loading, such as cracks in the asphalt layer in order to determine the proper diameter control and caused the asphalt to prevent damage. Slab drain is suitable to determine drainage asphalt diameter.